This is worth pausing on – yet another event on the timeline to smaller and faster. The folks at MIT, who appear to be the US answer to the Fraunhofer Institute, report in the New York Times today yet another step in making things faster.
We all know that the eye responds at a rate such that 30 frames per second (fps) or, better yet, 60 fps is indistinguishable from continuous to us. Electronic cameras of course do not have the limits of the eye (I once developed a system to operate at 3,000 fps). MIT operates in a different space than mere mortals and they have recently completed a somewhat faster camera at -- wait for it (but not too long) --
500 fpns = 500,000,000,000 fps
Now, why that number? A useful unit to carry around these days might be the speed of light, something that is difficult to make relevant, but here is an attempt. Light does not travel at 3x10^8 m/sec (it does, but who can relate), it travels at 1 foot/nanosecond. Those feet and inches just don’t go away. We can relate to the foot, but what about the nanosecond? Can we relate? Let’s try. When we’re in our car, we often go 60 mph, or, as you often learn in physics, 88 fps (as in feet per second). OK, now let’s think about the smallest unit of length we can visualize. Clearly we can see 1 mm on a ruler, so let’s make 0.1mm as the smallest thing we can see. Also, most of us get on a plane every now and then and go not 60 mph, but 600 mph.
So what can we almost relate to? 600 mph is 880 feet per second (about a football field’s length), about 10,000 inches per second (12X) or 250,000 mm per second (25X), or 2,500,000 of the smallest unit you can visualize (100 microns) in a second. Perhaps the main point of this little exercise is that we aren’t even close; we are only halfway there in log space and who can think in log space? If you can, you’re halfway there! We have no way to relate to the speed of a camera that is framing faster enough to “see” light travel through a scene. So you’ll just have to watch MIT’s video and not relate.
Check out the New York Times article with link to MIT video before it goes away (sent to me by Doug Nutter):
SCIENCE | December 13, 2011 Speed of Light Lingers in Face of New Camera By JOHN MARKOFF M.I.T. researchers have built a camera that can take images at intervals of a trillionth of a second.
This new camera is yet another pillar in the roadmap of science making light relevant. The article opens with a reference to Edgerton, whom I assume all readers know. If not, you may want to look at his images from the 1950s (or 1930s, can’t remember – there are some neat flip books at museums of his photos and you can get some of his images from the used book list). Edgerton was the master of scientific strobe photography. Also, you must be aware of the epic perspective book, “Powers of Ten” (if not, Google “Powers of Ten” and act accordingly). This is one of the absolute best books for appreciating the spatial scale of things. Clearly we now need, and can produce, the Powers of Ten in the fourth dimension – can’t wait.
The latest issue of Information Display from the Society for Information Display (SID) has a couple of articles that are somewhat of a high-end Consumer Reports coverage of TVs, particularly plasma. I, for one, had formed the opinion that plasma TVs were off the map as a personal consumer. Apparently, even if that may have been right the last time I bought a TV (I don’t do this very often), it is clearly not a given now.
The takeaway from the articles (should you not be a member) is that plasmas are now less expensive than competing LCD units. The key selection criterion is whether you watch TV in an environment with high-ambient lighting – that is, a room with floor-to-ceiling windows where you are watching when the sun is not down (who has time). If that is the case, then the clear consensus is LCD. However, if you are more of an after-the-kids-go-to-bed TV watcher, then plasma is the clear winner. Also, if you happen to be one of the few that have gone 3D, plasma is a faster technology that is intrinsically better for 3D.
Another valuable item from this issue is they point to a particularly educated purveyor of TVs in Scarborough NY, with an Internet presence: Value Electronics.
There are additional articles on the status of the higher-tech stuff you may be interested in. I am not in the market this year (or am I?) but I thought this was a valuable issue that you might otherwise miss.
Three items crossed through the ether on the weekend, one is somewhat long awaited (if you consider 5 years long), one that continues the march to making everything look inspiring, and one that even itself is not sure what it is. The one in the middle is not even a thing, it is software.
Starting with what could either be revolutionizing digital photography (again) or go into the laser disc category (I actually acquired a laser disc player with my most recent house, although I don’t have a laser disc) – the gadget being name the Lytro. Since these guys are probably copyright sensitive at this point, simply typing the code name, “Lytro” into Google will give you an onslaught of sites. For those who have not been following this, this is the first implementation of what has come to be called “Lightfield Imaging”, discover, invented, or recognized by Prof. McVoy at Stanford and his student Ng. It was first presented to the science audience at IODC in 2006, of all places. Even then, the answers to questions were, “you’ll have to talk to my lawyer”. This technology records not just a projected spatial intensity maps (what we call a photograph) but this device also records the intensity as a function of direction. Conceptually, the net results being you’ve stored all the data in 3D so that you can decide what is in focus in your photo whenever you want. Now, one might say – then why bother me, just put everything in focus. But, the developers seem to think there are photographers out there that feel fuzzy is artistic and therefore have allowed you to make whatever you want fuzzy, or sharp. On the Google list, it was noted that until Oct. 12, you couldn’t buy one without a “reservation code”.
Also, on the list, was something I started to hear about earlier in the week, but, it showed up as a specific link from John Tamkin. The new thing is, in my mind, Super Photoshop. Apparently there are many who want to add things to their photos, that aren’t there (I don’t get it, but, I’m becoming old school I can see). In any case, the site below guides you through how you can now add furniture to rooms that are lacking (actually in my house it would be to add floor where there are currently piles of books).
And, to complete the weekend there is the somewhat older news of Looxcie. This is a tri focal length web cam you can wear on your ear – something I always wanted to do? Available today through SkyMall (I’ve been on a lot of airplanes this month).
The catch phrases are “see what you see”, hmmm, and “catch those unexpected moments” – that can go few places. So, now you’re caught up. I’m not sure, yet, if you missed anything, we’ll see.
PS: Even before we could launch this out the door, yet another “photo toy” appeared on the web that many have enjoyed. Spotted by our web-watcher, Mark Kahan, this is the “ball camera” Quite fun too. 1 minute and 41 seconds – you can do it J
This is just in case you missed it. Over the weekend, the project that created Perkin-Elmer’s government division (near as I can tell, I worked there from 1980-1985) and led, I would imagine to the demise of Itek, was revealed in Washington. I had heard about the legends of “Big Bird”, the unclassified name for this program (for those that skipped this phase, many classified programs have unclassified names, they always have two words in them, so I’m told) for decades now. But, I must say, this thing is startlingly large. Phil Pressel, who has been leading the charge to declassify this mission, after CORONA’s declassification (Itek’s precursor to this) is someone I worked closely with at PE, on other programs. Phil has written a book and it is in the final stages of being approved for publication. You’ll be one of the first to know (and I’m counting on an autograph copy). So, if you haven’t seen this, read on –
PS – regarding actually seeing it, given that this was a short notice, one-day event that we all missed, if you can get into NRO, go, it is there, under a large tent I hear. If that doesn’t work for you (or me); next summer it is due to be unveiled for a 2-year run at the Wright-Patterson Air Force Base museum in Dayton, OH. OK, that is the only reason to go to Dayton, OH, but, I will be there and I’ll post something to perhaps encourage you to do the same.
The massive KH-9 Hexagon spy satellite on display at the Smithsonian National Air & Space Museum's Udvar-Hazy Center, after being declassified on Sept. 17, 2011. Longer than a school bus at 60 feet in length and weighing 30,000 pounds at launch, 20 KH-9 Hexagons were launched by the National Reconnaissance Office between 1971 and 1986. CREDIT: Roger Guillemette/SPACE.com
CHANTILLY, Va. – Twenty-five years after their top-secret, Cold War-era missions ended, two clandestine American satellite programs were declassified Saturday (Sept. 17) with the unveiling of three of the United States' most closely guarded assets: the KH-7 GAMBIT, the KH-8 GAMBIT 3 and the KH-9 HEXAGON spy satellites.
The vintage National Reconnaissance Office satellites were displayed to the public Saturday in a one-day-only exhibit at the Smithsonian National Air and Space Museum's Udvar-Hazy Center at Dulles Airport, Va. The three spacecraft were the centerpiece of the NRO's invitation-only, 50th Anniversary Gala celebration held at the center last evening.
Secret satellites that reveal targets even in night is the claim of the National Reconnaissance Office (NRO) - as evidenced by this NRO patch. CREDIT: NRO
Saturday's spysat unveiling was attended by a number of jubilant NRO veterans who developed and refined the classified spacecraft and its components for decades in secret, finally able to show their wives and families what they actually did 'at the office' for so many years. Both of the newly declassified satellite systems, GAMBIT and HEXAGON, followed the U.S. military's frontrunner spy satellite system CORONA, which was declassified in 1995. [See photos of the declassified U.S. spy satellites]
This National Reconnaissance Office released graphic depicts the huge HEXAGON spy satellite, a Cold War era surveillance craft that flew reconnaissance missions from 1971 to 1986. The bus-size satellites weighed 30,000 pounds and were 60 feet long. CREDIT: NRO
Big spy satellites revealed
The KH-9 HEXAGON, often referred to by its popular nickname "Big Bird," lived up to its legendary expectations. As large as a school bus, the KH-9 HEXAGON carried 60 miles of high resolution photographic film for space surveillance missions.
Military space historian Dwayne A. Day was exuberant after his first look at the KH-9 HEXAGON.
"This was some bad-ass technology," Day told SPACE.com. "The Russians didn't have anything like it."
Day, co-editor of "Eye in the Sky: The Story of the CoronaSpy Satellites," noted that "it took the Soviets on average five to 10 years to catch up during the Cold War, and in many cases they never really matched American capabilities."
Phil Pressel, designer of the HEXAGON's panoramic 'optical bar' imaging cameras, agreed with Day's assessment.
"This is still the most complicated system we've ever put into orbit …Period."
The HEXAGON's twin optical bar panoramic mirror cameras rotated as the swept back and forth as the satellite flew over Earth, a process that intelligence officials referred to as "mowing the lawn."
Phil Pressel, one of the developers of the KH-9 Hexagon's panoramic camera system, proudly points out some of the spacecraft's once highly-classified features, a life's work that he had been unable to discuss publicly until the NRO's Sept. 17, 2011 declassification of the massive spy satellite. CREDIT: Roger Guillemette/SPACE.com
Each 6-inch wide frame of HEXAGON film capturing a wide swath of terrain covering 370 nautical miles — the distance from Cincinnati to Washington — on each pass over the former Soviet Union and China. The satellites had a resolution of about 2 to 3 feet (0.6 to nearly 1 meter), according to the NRO. [10 Ways the Government Watches You]
According to documents released by the NRO, each HEXAGON satellite mission lasted about 124 days, with the satellite launching four film return capsules that could send its photos back to Earth. An aircraft would catch the return capsule in mid-air by snagging its parachute following the canister's re-entry.
In a fascinating footnote, the film bucket from the first KH-9 HEXAGON sank to the bottom of the Pacific Ocean in spring 1972 after Air Force recovery aircraft failed to snag the bucket's parachute.
The film inside the protective bucket reported contained high resolution photographs of the Soviet Union's submarine bases and missile silos. In a daredevil feat of clandestine ingenuity, the U.S. Navy's Deep Submergence Vehicle Trieste II succeeded in grasping the bucket from a depth of 3 miles below the ocean.
Hubble vs. HEXAGON
Former International Space Station flight controller Rob Landis, now technical manager in the advanced projects office at NASA's Wallops Flight Facility in Virginia, drove more than three hours to see the veil lifted from these legendary spacecraft.
Landis, who also worked on NASA's Hubble Space Telescope program, noticed some distinct similarities between Hubble and the huge KH-9 HEXAGON reconnaissance satellite.
"I see a lot of Hubble heritage in this spacecraft, most notably in terms of spacecraft size," Landis said. "Once the space shuttle design was settled upon, the design of Hubble — at the time it was called the Large Space Telescope — was set upon. I can imagine that there may have been a convergence or confluence of the designs. The Hubble’s primary mirror is 2.4 meters [7.9 feet] in diameter and the spacecraft is 14 feet in diameter. Both vehicles (KH-9 and Hubble) would fit into the shuttle's cargo bay lengthwise, the KH-9 being longer than Hubble [60 feet]; both would also fit on a Titan-class launch vehicle."
The 'convergence or confluence' theory was confirmed later in the day by a former spacecraft designer, who declined to be named but is familiar with both programs, who confided unequivocally: "The space shuttle's payload bay was sized to accommodate the KH-9."
The NRO launched 20 KH-9 HEXAGON satellites from California's Vandenberg AFB from June 1971 to April 1986.
The HEXAGON's final launch in April 1986 — just months after the space shuttle Challenger explosion — also met with disaster as the spy satellite's Titan 34D booster erupted into a massive fireball just seconds after liftoff, crippling the NRO's orbital reconnaissance capabilities for many months.
A side view of a KH-7 GAMBIT spy satellite on display at the Smithsonian National Air and Space Museum's Udvar-Hazy Center at Dulles Airport, Va., on Sept. 17, 2011. CREDIT: Roger Guillemette/SPACE.com
The spy satellite GAMBIT
Before the first HEXAGON spy satellite systems ever launched, the NRO's GAMBIT series of reconnaissance craft flew several space missions aimed at providing surveillance over specific targets around the world.
The satellite program's initial system, GAMBIT 1, first launched in 1963 carrying a KH-7 camera system that included a "77-inch focal length camera for providing specific information on scientific and technical capabilities that threatened the nation," according to an NRO description. A second GAMBIT satellite system, which first launched aboard GAMBIT 3 in 1966, included a175-inch focal length camera. [Related:Anatomy of a Spy Satellite]
The GAMBIT 1 series satellite has a resolution similar to the HEXAGON series, about 2 to 3 feet, but the follow-up GAMBIT 3 system had an improved resolution of better than 2 feet, NRO documents reveal.
The GAMBIT satellite program was active from July 1963 to April 1984. Both satellites were huge and launched out of Vandenberg Air Force Base.
The satellite series' initial version was 15 feet (4.5 m) long and 5 feet (1.5 m) wide, and weighed about 1,154 pounds (523 kilograms). The GAMBIT 3 satellite was the same width but longer, stretching nearly 29 feet (9 m) long, not counting its Agena D rocket upper stage. It weighed about 4,130 pounds (1,873 kg).
Unlike the follow-up HEXAGON satellites, the GAMBIT series were designed for extremely short missions.
The GAMBIT 1 craft had an average mission life of about 6 1/2 days. A total of 38 missions were launched, though 10 of them were deemed failures, according to NRO documents.
The GAMBIT 3 series satellites had missions that averaged about 31 days. In all, 54 of the satellites were launched, with four failures recorded.
Like the CORONA and HEXAGON programs, the GAMBIT series of satellites returned their film to Earth in re-entry capsules that were then snatched up by recovery aircraft. GAMBIT 1 carried about 3,000 feet (914 meters) of film, while GAMBIT 3 was packed with 12,241 feet (3,731 meters) of film, NRO records show.
The behemoth HEXAGON was launched with 60 miles (320,000 feet) of film!
This image shows the flight profile for the NRO's GAMBIT 3 spy satellite missions between 1966 and 1984. The program was declassified in Sept. 2011. CREDIT: NRO
HEXAGON and GAMBIT 3 team up
During a media briefing, NRO officials confirmed to SPACE.com that the KH-8 GAMBIT 3 and KH-9 HEXAGON were later operated in tandem, teaming-up to photograph areas of military significance in both the former Soviet Union and China.
The KH-9 would image a wide swath of terrain, later scrutinized by imagery analysts on the ground for so-called ‘targets of opportunity.' Once these potential targets were identified, a KH-8 would then be maneuvered to photograph the location in much higher resolution.
"During the era of these satellites — the GAMBIT and the HEXAGON — there was a Director of Central Intelligence committee known as the 'Committee on Imagery Requirements and Exploitation' that was responsible for that type of planning," confirmed the NRO's Robert McDonald, Director of the Center for the Study of National Reconnaissance.
NASA's Rob Landis was both blunt and philosophical in his emotions over the declassification of the GAMBIT and HEXAGON programs.
"You have to give credit to leaders like President Eisenhower who had the vision to initiatereconnaissance spacecraft, beginning with the CORONA and Discoverer programs," Landis said. "He was of the generation who wanted no more surprises, no more Pearl Harbors."
"Frankly, I think that GAMBIT and HEXAGON helped prevent World War III."
Editor's note: This story was updated on Sept. 19 to correct the name of Phil Pressel, who designed the HEXAGON spy satellite camera system.
I’m in at the University Bordeaux this week learning about their research in virtual and augmented reality, where I was invited to ArcheoVision. This is a museum of archeology that is experimenting with the use of virtual reality combined with robotic replication based on high technology laser scanning to creative an environment that will attract, educate, and entertain the public without compromising the science of archeology, including monster (15 foot) reproduction marble statues (very cool – you can even order your own - $30,000). They also offer to scan your head in 3D and make an accurate marble bust, for, you know what, only $2,999 (actually very cool too, we’re considering it).
We met with Prof. Robert Vernieux, an archeologist’s archeologist who spent nearly 15 years in Egypt. He is now involved in many things, one being creating 3-D environments for the general public. There are a few paths. In one case, they have created a 3-D image file of ancient objects, which are then projected in a small theater environment, with some reasonable quality projectors. In this way, otherwise small perhaps nondescript objects can become a center of attention. Rather than lying up on the screen, 15 feet away, the 3D projection can effectively place it in your hand as a sharp, clear, fascinating image. When combined with the lecture that places the piece in context, for a scientist at least, it definitely keeps you awake. The second series we saw was a projection of antique amateur stereo postcards. What has happened is Prof. Vernieux came upon a collection at a market in Egypt and brought them back to France where they are scanned and interfaced to the auditorium projectors. Again for me at least, these were fascinating and I think I could have easily watched them for an hour. Based on the success of the stereo postcards he found, from 1868 and 1903, of ruins in Egypt being excavated by archeologists, the center has advertised that they are accepting donations of stereo postcards from Egypt. They have been sent thousands that they are now scanning. But, the public is not coming in droves. The place is rather quiet.
Now, to the point. A group of scientists then gathered for a few hours to discuss whether 3D is viable. It is not clear. It is currently a technology that is extremely data intensive and often overwhelmingly time consuming. The consensus is the 3D technology is currently somewhat of a toy, that pretty much everyone enjoys, for about 10 minutes, and then they say, “is that all there is?”, the answer often being – yes.
An interesting observation, after designing a 3D “Cave” experience for the museum; everyone remembers the Cave, the delivery of the 3D technology, and no one remembers the archeology. This is not the goal.
So, as always, this is just a random musing, but, it will be interesting to see if 3-D becomes a standard technology in the next decade, or, goes the way of the laser disc player (which I happened to inherit with the house I recently bought – I have a great player, but, no discs – may have to do something about that).
Should you speak French (I don’t), you might enjoy,
Last week found me at, among other things, the NASA SBIR conference on mirror manufacturing. The main attraction being the last day visit to the Goddard Space Flight Center (GSFC) to see what can be seen of the integration and test of the mirrors and the instruments (NIRCAM, NIRSPEC, MIRI, and FGS). There is encouraging news. It does appear that most of the hardware now exists for both the telescope and the instruments. Each of the instruments arrived at GSFC during this year and they are in some phase of initial testing. GSFC is the facility where the thermal and vibration testing will occur as well as integration and testing.
At the conference, Glatzel (yes, the son of the optical designer who inspired Juan Rayces optical design algorithm, found in Eikonal) reported that Tinsley (the L3/SSG version, not the ZYGO/ASML version) has delivered the last of the mirrors and yes, they are defining the state-of-the-art. The numbers are not yet packaged for public dissemination, but, they are impressive.
Now, what about that title? I have no idea how many of you know that the number of seconds in a year is conveniently close to the number π x 107 (365x24x60x60=31,536,000), something that was pointed out to me back in undergraduate days. So, although it did “feel” like the JWST is moving out of the one challenge after another (which can be fun, but expensive) phase and into the relatively routine. This probably not quite the case, but, the project does appear to have moved to an important to phase. Below is a shot of one of the spare segments in a GSFC clean room (a really big one, as are most of the facilities at Goddard.
A spare segment from the JWST.
Following the center tour, Joe Howard, working with the host Phil Stahl and Peter Blake arranged for the group to see the “Science Sphere”. This is pretty fun. It is a suspended sphere, about 4-5 ft in diameter that forms for the screen for 4-6 projectors that are nicely integrated. Perhaps most impressive, the projectors can be fed by real-time data. There is the weather, including for example the worldwide weather in the summer of hurricanes, including, of course, Katrina. But, the most compelling was to watch the air traffic world-wide, in real-time – fascinating (and then we had to catch the airplane). One of the colorful earth resource images (somewhat fuzzy due to the lighting and motion) is below. If you get near the GSFC visitor center, be sure to arrange to see The Sphere.
An image from “The Science Sphere” at the GSFC Visitor Center.
In 1966, a forum was held at the University of Rochester titled “Lens Design with Large Computers”, following on the heels of a less formal, and less documented, event in a similar vein in 1964. Ten years later, I found myself at my first summer job in the optical design department of Perkin-Elmer (where I helped with the tolerance sensitivity analysis for the Space Telescope, Fine Guidance Sensor and test setups for AXAF (what becomes Chandra, in 25 years), little knowing it would not be relevant for a full 20 years), working with authors of some of those 1966 papers.
This is brought to mind by the IBM event of the decade, the Jeopardy Show. When Big Blue took the chess title in the first challenge, it was immediately obvious that yes, this would affect me directly. Why? There are many parallels between chess and optical design. Sure enough, within 5 years, the global optimizer in CODE V, which was merely a concept for debate at the 1994 IODC conference, was challenging the best designers. In fact, 2003 was the last time anyone on my staff claimed they were better.
So, what does the Jeopardy Show mean for lens design? At dinner with a chaired professor in the interaction of humans with machines recently, he threw out the following disturbing observation. What is going to happen when the computer becomes the expert, who will teach the computer new things? Under the assumption that those currently espousing that the field of lens design is no longer necessary, with computational focal planes will only commandeer 60-80% of the application space, who will be teaching who in 30 years.
Looking at the history, as was written earlier, optics is often found at the leading edge of technology. James Baker represents the first, and some might say one of the best examples of a lens designer developing a computer-aided optical design environment. He, along with Robert Hopkins, also a ardent designer, independently led the emergence of computer-aided optical design from 1945 – 1955. By 1955 there is a mix of mathematicians, like Donald Feder at Kodak and optical designers, such as the founder of ORA, Tom Harris, working to move the software on many fronts, but primarily optimization running up to the 1968 conference. If we look at the 1968 authors, listed in Table 1, we see the lens design community is the dominant source of papers.
Speaking from the American history alone, from 1970 to about 1990 there were a few smaller companies, including Scientific Calculations (ACCOSV), ORA (CODE V), David Gray (Cool/GENIE?), Doug Sinclair (OSLO), and a few other independents developing optical design codes to support their optical design consulting. More prominent in this period were the codes under development at major aerospace companies led prominently by what was then Hughes/El Segundo and LMSC Palo Alto Research and the specialty reconnaissance companies like ITEK and Perkin-Elmer. Beginning in 1980, I was at Perkin-Elmer, where I spent my evenings, for two years, learning the 200-300,000 lines of code and beginning to expand its capabilities to include, for example, circular gratings in support of AXAF. In this period, pretty much across the board, lens designers were driving the developments. However, by the late 70’s, things started to evolve (or devolve depending on your perspective) as the accountants started to realize what it was costing to maintain the code, typically $2-$3M per year and companies like ORA were offering a comparable, or often better product for a mere $1000/month, (per designer). By the mid-80s, I had moved to ORA, seeing the end of software support at Perkin-Elmer, but, notably where I was presented with in retrospect, a historically significant choice, join the software “department”, OR join the optical design group. Having no formal training in software, I went with the design group.
So how does this all relate to Jeopardy? The thought question is, as computer become more and more expert at, for example lens design, the number of experts in optical design will, by necessity (read economic pressures) decline. Could this number approach zero in 20-30 years? And if so, where are we? Will computers intelligence rise to not only make the execution of code something only “they” can do, but, also find paths to new ways to solve problems or adapt to the evolving technology? And, if they do not, who will be left to teach them?
Recall the events of WWI, when the British and the Americans both woke up one morning to realize the had fewer than 5 optical designers in the entire country and worse yet, even if they could execute a binocular design they had forgotten how to make glass. It does seem déjà vu may be on our horizon.
The Optifab conference is happening this week in Rochester (May 11 -13). One of the highlights will be a panel discussion on the Q-type (Forbes) Polynomial Surface, which I am moderating in the Empire Hall from 2-3pm on Wednesday, May 12.
Two years ago was the first Optifab conference that I attended in Rochester. The event of note that year, at least for me, was the attachment developed for the QED aspheric stitching interferometer (ASI), which was the motivation for the Forbes polynomial. Note that in this informal setting, I am retaining the “Forbes” label on the polynomial; out in the optics community, there is a move away from this personalized reference to a new, yet-to-be-fully-adopted standard. Synopsys has selected “Q-type” polynomials as the identifier in their recent, full release of the polynomial in CODE V. (Along with the implementation of the polynomial, including painless converters to and from the power series representation, Tom Kuper has developed and implemented a guidance tool for CODE V called Asphere Expert, which indicates where to best place an asphere in an optical system.)
The QED ASI attachment is a very clever solution for aspheric testing. It includes an adjustable refractive wedge that is a plano-concave lens, plus a matching convex-plano lens that provides a spherical seat in which the two components rotate to create a wedge. On my list is to develop a nodal aberration description of how it works.
In the intervening two years, the Forbes polynomial has matured and entered the mainstream tool set. However, as with everything new, the transition is slow. The panel forum at Optifab is intended to motivate a discussion of where we are at this point in time. There are stories from the street that, at least by the time they reach me, are positive to very positive. At the same time, the Forbes polynomial implementation has, in the short view, increased the time per cycle in optimization. However, I will argue that if one steps back to look at the time cycle of an entire project, the key metric – the time spent to achieve predicted as-built performance – is in fact reduced. My argument is based on a lengthy, very realistic study of a high NA lithography lens conducted by Bin Ma, PhD, in conjunction with Prof. Rolland at the University of Rochester. Even more significant, for a given set of technology driven minimum limits, designs incorporating Forbes polynomials are achieving new levels of performance, when the slope constraints are used during optimization.
A key result is shown here, for the first time in public. The first chart provides the sensitivity to decenter of a 29-element lens with seven aspherics, created by Bin Ma based on a realistic optical design specification before the slope-constrained Forbes polynomial was available. The second chart shows the result for a lens developed with the slope-constrained Forbes. To achieve a factor of two and more improvement in this very mature technology is a compelling result.
Following the panel discussion, arrangements are being made to present and discuss the results of Bin Ma’s work at the Synopsys booth.
The sensitivity of a state-of-the-art 193nm high NA litho lens design developed a) without aspheric slope constraints and b) with Q(Forbes)-polynomials with slope constraints. (Preliminary data provided by Prof. Jannick Rolland and Bin Ma, to be published)
As I mentioned in my last entry, I gave a talk at last week’s UK Optical Design Meeting highlighting a paradigm change in glass selection and optimization in optical design. The viewgraphs from my talk are available as a PDF file:
This talk highlights a very significant change in optical glasses that has occurred in response to the environmental movement. As you may have noted, Canon and other Asian camera manufacturers began putting green-friendly labels on their camera lenses a while back. I recall the first time I saw one, thinking it was a somewhat odd concept. However, what it has become in fact is both an amazing marketing move that advanced the Asian glass manufacturers to the top of the food chain and at the same time has changed the course of optical design. In discussions at the UK optical design meeting last week, they noted that the EU may have been the leading factor by issuing new, very strict rules especially in relation to lead.
As seen in the viewgraphs, a sample from which is above, the first optical glass catalog from Schott in 1886 offered 76 glasses. I have plotted them on the current standard index versus V-(Abbe) Number chart. From there, the Schott catalog expanded to over 250 flavors of glass, with the most significant addition being the addition of the LA series of glasses. When I entered the field in the 1970s, Schott owned the market, with the Asian suppliers barely visible. However, the very real pressure for environmental reform, particularly in Europe, forced Schott to re-evaluate its position. Combined with the economic pressures of carrying so many glass flavors, they took this opportunity to reduce their catalog substantially, returning essentially to the 1886 situation, other than the LA glasses. This is shown clearly in the viewgraphs of the talk.
What this has done to the optical designer is to have taken what had become for all practical purposes a continuous glass map, and made it in some regions sparse and in all regions an effectively discrete set. This changes standard methods of optimizing with continuous variable glass descriptions within a boundary for index and dispersion. As shown below, the current catalog is now far from continuous. For perspective, the 1886 glasses are also shown illustrating that except for the LA-series glasses (and to some extent the FKs), the catalog is somewhat similar in density from this perspective.
This is a very significant change. In terms of optical design, the continuous strategy used to-date must be converted to a discrete strategy. This has been done in CODE V and the results, which are dramatic, are illustrated in the slides provided in the talk.
If you are a practicing lens designer, and you have not really realized the impact of the “sparsification” of the glass catalog, I highly recommend following the link above to the talk and reviewing the important results shown there.
The amount of information we deal with on a daily basis is expanding. We must remember passwords for our email accounts and bank accounts, phone numbers, shopping lists, to-do lists, and the list goes on. However, there is a finite limit to our immediate memory capacity. The availability of wireless networks, miniaturization of electronics and sensing technologies, and novel input/output devices has given rise to mobile information display devices suitable for “on-the-go” daily use. For example, cell phones have become the center of daily communication and personal information management needs for many people.
The ORA Engineering Services team envisions a future in which people will transition from handheld cell phone displays to a more elegant solution to mobile information needs: head-worn personal displays. We have developed optics for a personal display prototype that we believe provides unique advantages to help enable this transition.
At the Optics + Photonics show this month, we had the opportunity to exhibit the personal display. You can view a video and article about the personal display on the Laser Focus World website.
A key differentiator of the glasses used in the ORA personal display (Figures 1 and 2) is the excellent ophthalmic quality see-through capability. The ORA personal display glasses make use of an off-axis optical design as illustrated in Figure 3, which is an area of high expertise for our engineers, with three of the team’s designers earning PhDs in this specific field of optics and optical design. The design form is scalable from a 20-degree diagonal full field of view to a 100-degree diagonal full field of view (the size of the glasses will scale up or down with the field of view). The 100-degree solution, also developed by ORA, is in production now as the Link/L3 AHMD simulator display. The ORA personal display has the following high-level specifications:
Eyebox diameter: 10 mm Eye clearance: > 15 mm Full Diagonal field of view: 20 degrees Panel resolution: 432x400 Distortion correction is achieved by an electronic warper.
Figure 1
Figure 2
Figure 3 Off-axis relay and combiner
If you’re interested in finding out more about the ORA personal display, feel free to email me (kevin@opticalres.com).
On a recent business trip to Toulouse, France, I had a few hours free one day, and I visited a space museum called Cité de l’Espace. This excellent museum has many indoor exhibits related to space exploration, the solar system, and astronomy. It also has a number of outdoor exhibits, most of which are life-size mockups of various spacecraft, including the Russian Mir space station and the gigantic Ariane 5 launch vehicle (53 meters tall). There is also a large-scale model of the solar system, which illustrates the correct relative sizes (but not distances) of the planets.
The only spacecraft model of a directly optical nature is the ESA XMM-Newton x-ray telescope (launched in 1999, still operational). A separate building houses a large-scale digital planetarium and an IMAX Theater, which was showing the film Hubble 3D. This is a beautiful film celebrating the history and the amazing imagery of the Hubble Space Telescope (HST). The film incorporates 3D IMAX footage that was shot by NASA astronauts on the final Hubble servicing mission (STS-125) in May 2009. The huge IMAX 3D camera was installed in the shuttle’s payload bay and positioned so it could film the space-walking astronauts as they worked on repairing the enormous HST, which had been captured and mounted on the repair platform in the rear of the payload bay.
The space walks were long, but the film clips had to be brief since they only had 8 minutes and 30 seconds of film installed. The 3D clips shot on the mission were combined with IMAX footage from previous service missions, as well as training footage and scenes of the astronauts inside the shuttle discussing the mission (and joking around). In addition, many of the astronomical images from HST were edited to show beautiful 3D effects that strongly demonstrate that these are indeed huge, 3D objects in space. The beautiful Hubble images really seem to come alive as you fly through nebulas and star nurseries and onto the very edge of the known universe.
Just a quick note about SID 2010. The SID exhibition is a great place to see the TV you want in your living room or bedroom, in about five years. This year did not disappoint. The clear, out-and-out winner this year was the LG 84” 3-D Home Theater. Coming on the heels of Avatar, this unit is stunning for its size, clarity, color saturation, and by far the best 3-D of the show in this size group -- at least that I saw. The other truly amazing unit was an LED TV, about 72 inch format, 3mm thick. Very cool on the wall. Often these units never make it to the consumer, but if the LG unit does, it just may find a place in my home.
The best talk at SID, I thought, was the plenary on the history of airplane cockpit design by a veteran Boeing designer (we were in Seattle after all), Mike Sinnett. He had a photo of the first Boeing cockpit – a single seater, and then a photo series of great moments in airplane cockpits. He made the interesting point that the parameters of interest are the number of people up front and the number of windows. This peaked, as I recall, with five people in the front cabin: pilot, copilot, radioman, navigator, and manager. I believe it had seven windows. The last transition was to convince the union that a move from three to two people, even in the biggest plane, is acceptable.
With IODC upon us, this is a short entry, but I didn’t want to miss the chance to send accolades to the speaker. And by the way, to see more interesting Boeing photos, try a Google images search on “Boeing & cockpit”.
The other interesting plenary was from a to-be-unnamed technology company. A very well prepared marketing plenary tried to convince me that one of my hands is now destined to carry a cell phone that I will squint at for all sources of news and entertainment. I refuse to believe this is the future of civilization. This has reinforced my resolve to help bring see-through augmented vision displays to the world, maybe in less than 10 years.
Hope to see you are IODC. Come up, say hello, get a book and the collected works of David Shafer, and let me know how to keep this little site interesting and relevant to you (or, just e-mail me).
For those in science, and particularly those in optics, we know that the eye responds to only a limited range of all possible wavelengths that are shooting past us. We know short of deep blue there is the UV (and skin cancer). The long of deep red is the infra-red, then eventually heat, and on to radio waves, extending eventually to the water waves on a lake, in a less abstract medium. What if we had a button that allowed us to see other wavelengths?
Well, electronic detectors, like those on the Hubble Space Telescope (HST), let us do just that. By encoding wavelength information we cannot see in a spectrum that we can, we can begin to learn what the world, and better yet the universe, looks like at other wavelengths, and in fact how much there is to learn. In fact, one important point when it comes to the universe is that light arriving here from far away is also very old—billions of years. Light travels fast enough to circle the earth at the equator about 7 times in a second, but, on the scale of the universe that is actually pretty slow. This old light is red-shifted (I am not going to cover this today), meaning, even if it starts out blue, by the time it gets here, it is not even red—it is deep in the infra-red.
Subsequently, the new James Webb Space Telescope (JWST) , designed to routinely look to and try to understand the edge of the universe, and therefore the edge of time (and no, I’m not going there today either), will have detectors that are designed to only see infrared light that we cannot ourselves “see”. Starting at a large scale with the space-based telescopes of the last 20 years, we have been building a massive database of information in colors that we cannot ourselves see, including x-Ray (Chandra) and deep Infra-red (WISE).
That brings us to today’s “find”, which comes to us from ORA’s Mark Kahan. It came to Mark from a friend, Art Ferruzzi, who is always on the lookout for interesting Internet articles in science. There is now a web-link where you can call up regions of the sky/universe and dial in the wavelength bands you would like to “see”.
Somewhat reminiscent of recent photo reconstructions of space where they remove the “new” objects and leave only the really “old” ones, this view of our universe is truly inspiring.
It so reminds me of something I was once asked in high school, as I was labeled as the science kid in the group. My friend from the age of 4 said to me, “I really hope I get to travel into outer space and go to another planet to see different colors”. That was somewhat a confused view of the world, but, I will be forwarding this website to him next and let him know his wish has been granted, more or less.
Since we always like to have a graphic, this is one of my favorites, as I was not able to copy off of the live site successfully. On the left, the darkest region in space over the format of the Hubble Space Telescope as seen from the ground in ultra-deep exposure mode (i.e., a region with the least number of objects). On the right, the same region shot with the Hubble following the 1st repair mission. Soon to be surpassed, I believe, by the new equipment. If anyone happens to spot a new shot of this region, do let me know.
Today Mark Kahan, ORA’s Chief Electro-Optical Systems Engineer, has contributed a short Guest Blog on NASA’s Wide-field Infrared Survey Explorer (WISE).
Mark is a Member of the WISE Standing Review Board, and, among other areas, he was involved in a number of different aspects of the Hardware, from Design through Test, and on to Cover Deployment and On-Station Performance. Many of the WISE Lessons-LearnedJ, over various Engineering & Managerial aspects, will be covered at the SPIE’s Annual Meeting in San Diego on 1 August 2010 as part of a broader Session entitled “An Optical Believe It or Not: Key Lessons Learned”.
The WISE mission was competitively selected under NASA's Explorers Program which is managed by the Goddard Space Flight Center (GSFC), Greenbelt, Md. The Science Instrument was built by the Space Dynamics Laboratory, Logan, Utah, using a Cryogenic Telescope, Aft-Optics, and Scan Mirror (shown to the right) built by SSG-Tinsley/L-3 Communications, Wilmington, MA, and the Spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, under the watchful eye of Ned Wright, the WISE Mission Principal Investigator (PI). Caltech manages JPL for NASA, and JPL was the Lead NASA Center relative to the responsibility of insuring the Hardware was built-to, and is performing to, Specifications (see http://www.jpl.nasa.gov/wise/)
WISE launched Dec. 14, 2009, from Vandenberg Air Force Base in California, and it will spend nine months scanning the sky in infrared light, revealing all sorts of cosmic characters—everything from near-Earth asteroids to young galaxies more than ten billion light-years away. Before the Mission ends it should uncover hundreds of thousands of asteroids, and hundreds of millions of stars and galaxies. Its vast catalog of data will provide astronomers and other missions with data to mine for decades.
Because so much has been written about WISE, this Blog will concentrate on providing a bit of added insight into the WISE First Light Image, and in doing so we can see why WISE has astronomers so excited.
Before WISE launched, this is what we could see at 3.5 microns in one area of the sky about three times the size of the full moon:
We could see a bit more at 12.5 microns:
Then we opened up the WISE Cover, and this is what we saw in the same area of the sky:
The 1st light WISE picture shown above was taken looking at the constellation Carina which is near the Milky Way (about 5 degrees out of the plane of our galaxy called the ecliptic). We were Nadir pointing (i.e. we were pointing away from the earth, which is important so as to keep WISE cold), and we were in the Southern Hemisphere, probably over South America. We were staring at one region of the sky by controlling the S/C reaction wheels. Though this first image was captured as the spacecraft stared in a fixed direction in order to help calibrate the WISE pointing system, the mission's survey is being done while the satellite continuously scans the sky, and an internal scan mirror counteracts the S/C motion to create 8.8 second freeze-frame images.
The "first-light" picture shows thousands of stars and, as was noted above, it covers an area ~ three times the area of the full Moon (WISE’s FOV is about ¾ of a degree by ¾ of a degree – actually 47 arc-sec, and the Moon is ~ ½ Degree). Eventually, if nothing goes wrong, WISE will take more than a million similar pictures covering the whole sky.
The first light picture shows infrared light from three of WISE's four wavelength bands: blue, green and red correspond to 3.4, 4.6, and 12 microns, respectively. There’s a 25+ micron band too, but it wasn’t included for convenience and to speed up the processing to get the 1st image out-the-door (3 color printing is common; sometimes folks add a couple of bands into one of the 3 colors to add further information, but that wasn’t done in the first-light image).
The star labeled V482 is a bright M2 Giant [RA (2000.0): 093023.66, Dec. (2000.0): -582143.2] located about 1,000 (1,058 +230/-160) light years away from Earth, and is about 6th Magnitude (5.9, actually) in the visible wavelength region. Also, since it is a red giant star, it is quite a bit brighter in the infrared, almost first Magnitude by the time one gets to 2 microns (it is ~ 0.5 Magnitude in Bands 3 & 4, around 12 microns and 25 microns, respectively). A hot star like Vega will have the same optical and IR Magnitudes, while a cooler star will have brighter (smaller number) Magnitudes in the IR than the visible.
One question that comes up a lot on the WISE 1st Light Image (because it sort of sets a sensitivity threshold for comparison) is “Would the bright star be visible with the naked eye?” The answer is “Yes”. V482 Carinae is barely visible to the naked eye from a dark site. Bigger Magnitudes are fainter, and we usually say the naked eye limit is 6, though some people can see 6.5 and a few can even see 7 (sadly I can see less every year!). Each Magnitude is about a factor of 2.5 in brightness, and 5 magnitudes is exactly a factor of 100, so a Magnitude 1 or first Magnitude star (which is about what stars like the Belt of Orion or the Big Dipper are) are 100 times brighter than 6th Magnitude stars.
With 5-sigma surety, for hot stars with no IR “excesses” (a long discussion in and of itself), WISE can see down to < 16th Magnitude in Band 1, < 15th Magnitude in Band 2, < 11th Magnitude in Band 3, and under 8th Magnitude in Band 4.
Because this V482 star is at declination -58 degrees, you need to be at latitude -58 degrees for it to come overhead, and you can't see it all from the ground if you are north of 32 degrees latitude on Earth (which is the case for both Pasadena at 34.15 degrees, and Boston at 42.32 degrees).
Finally, WISE Pixels are 2.75 arc-seconds in size at the shorter 3 wavelength bands, but we agglomerate 4 pixels (so we’re 5.5 arc-sec by 5.5 arc-sec) at 25+ microns. The FWHM in the shorter bands is ~ 6 arc-sec and it varies over wavelength (in Noise Pixel/NP Terms we run from 12 to 40 NPs over wavelength band, at least when we’re staring; things go up a smidge when we’re scanning).
It’s great to see thousands of the tiniest of details come together in such a great way. Go WISE! J
In case you missed it, as many have been saying, there is a new, significant telescope now operational in space. The “first light” photos have been posted at
To get some background on the telescope, there was an article in the LA Times earlier in December (that I missed, but Frank Moreno of ORA passed along. That link is
ORA’s own Mark Kahan was heavily involved with this program. One of his recent roles, which is a somewhat obscure, but essential, corner of science is to ensure that all the necessary conditions are met to be sure the protective cover on the telescope actually does come off. A problem encountered in an earlier test of an important space asset. I’ll see if I can get him to write something on this, some time soon. In the interim, enjoy the photos of space.
COSTAR Corrective Optics Space Telescope Axial Replacement (COSTAR), "Contact Lenses for the Telescope," on display at the new "Moving Beyond Earth" gallery in the National Air and Space Museum's Mall building.
Image Number: WEB11281-2009 Credit: Photo by Eric Long/NASM Copyright: Smithsonian Institution
In a May service mission, the systems WFPC2 and COSTAR were brought back to Earth. WFPC2 is the oversized digital camera that recorded so many of the Hubble Space Telescope’s iconic images after its installation by shuttle astronauts in 1993. COSTAR is the other optical system that was installed in HST on that same first service mission. Its carefully designed and fabricated mirrors “popped out” into precise locations in the optical path to compensate for the famous error in Hubble’s primary mirror, allowing the originally installed science instruments to “see” sharp imagery from the telescope (WFPC2’s design incorporated its own correction and didn’t use COSTAR).
Now the camera that photographed so many stars is something of a “star” itself, on display in the main space gallery at the National Air & Space Museum in Washington, DC. And COSTAR is there too (pictured above), part of a new exhibit called “Moving Beyond Earth.”
Last weekend I had the pleasure of taking an “insider’s” tour of the Large Binocular Telescope (LBT), currently the largest telescope in the world based on baseline (22M) and I believe collecting aperture (although it’s hard to keep track), at 2X8.2M. It was a very nice afternoon and the trees at the peak (10,200’) had turned a brilliant fall yellow.
Since one of my first experiences in optics was to star test one of the last of the six original mirrors in the Multiple Mirror Telescope (MMT) on Mt. Hopkins south of Tucson, it was quite a reset to view how massive the LBT building is compared to the original MMT building, which can be seen from the LBT. At one point we trekked all the way to the roof (OK, a lot of the trek involved a series of elevators), which is over 200 feet off the ground, to an unseen tiny cement escarpment that provides an amazing view back to Tucson and beyond. In that we are recently applying nodal aberration theory to these telescopes, it is an interesting perspective to look at an 8.2M mirror and then contemplate the question, what does a 10-micron decenter actually mean? With these mirrors, there is no absolutely smooth edge circular aperture to measure from. These are spin-cast mirrors made at Roger Angel’s lab in Tucson and as such the edge is good, but is not a micron-level reference surface. The experience reminds me of when I worked on an Air Force conformal optics project. We kept asking for the wing profiles to a number like 10 microns. The Air Force finally decided the best response was to put us on a plane to St. Louis, where we learned airplanes are made pretty much the same way as a Grumman canoe, containing over three miles of wire. They do not work well as an optical reference surface.
I came across a website titled, “100 Hours of Astronomy,” which was created in the spring of this year as part of the global celebration of the 400th anniversary of the first use of an astronomical telescope. I did not spend much time there, but it appears to be a tremendous series of on-site interviews with astronomers at telescopes around the world. I look forward to taking some time to explore the website – enjoy!
Solar energy is of growing interest and importance in the world, and optics play a big role. Optical design is needed for concentrating photovoltaic systems as well as solar thermal systems (although the optics in those systems are often a bunch of flat mirrors tracking the sun). ORA’s illumination engineers have been working on a lot of solar technologies the last few years, and we have developed some special software tools to help out with this work.
LightTools image of solar trough system
There are some enormous solar thermal installations operating in Spain and the United States, with more on the way in the next few years. But sometimes improvements in solar energy performance come down to the small things – and making the small things smaller. For example, an article in MIT Technology Review, “More Efficient, and Cheaper, Solar Cells” (http://www.technologyreview.com/energy/23459/), discusses improvements to conventional solar cell manufacturing that could significantly increase the efficiency of multicrystalline silicon cells and bring down the cost of solar power by about 20 percent. This development was announced by a startup company, 1366 Technologies of Lexington, MA. The key to this work is figuring out how to reduce the shadowing and rejected photons caused by metallic conductors on the surface of the solar cell. People have found various ways to do this, but 1366 Technologies claims to be able to do it very cheaply with methods that fit well into standard production processes. They’re looking at increasing cell efficiency from the current typical 15-16% to 18% right away, with hopes of reaching 19% after further development. This has been demonstrated at production scales, not only in the lab.
The new instruments are more sensitive, promising more efficient observations and the ability to look deeper into the past by imaging extremely faint distant galaxies.
The JWST is the telescope that will follow Hubble Space Telescope. It is something I thought to write about because it is not that easy at the moment to get information about the optics details in particular of the telescope.
At the just ended 2009 SPIE Annual meeting, I presented my work to create an estimated model of the very complex (from an optical design perspective) NIRSpec instrument being built now, in Europe, for the JWST. This instrument consists of the JWST (an obscured, field-biased Three Mirror Anastigmat (TMA) followed by a Relay, Collimator, grating, and Camera, each of which is itself an unobscured TMA. I will write more on this paper at another time.
The WFPC2, recently replaced in the Hubble by the WFPC3, took many of the most famous pictures of the cosmos. It may be the most famous single camera in history. JPL has recently written a couple of articles on this legendary camera, first installed in the Hubble in 1993. It has been receiving lots of “retirement accolades” recently, some which you might find interesting.
With the last mission to the Hubble space telescope recently completed, successfully, I thought to post my role in the First Servicing Mission, the one that was critical to the overall mission of NASA to keep the public engaged with astronomy. I had a somewhat unique position in the program and a critical role in the repair (or as they prefer to call it, “servicing”).
I intend to write on this topic over a series of sessions, primarily to provide my somewhat unique view of the servicing mission. The success of the Hubble First servicing mission had many key contributors, and I was happy to be one of them. It turned out that this was one of my last major technical contributions before being moved into management.
I have a unique view of the Hubble First Servicing Mission because I was at Perkin-Elmer, the company that made the perfectly wrong primary mirror, during the period when they made the wrong mirror. As a result, I know first hand the conditions that team was working under. In this first writing, however, I am choosing to point out something that was nicely featured in the recent PBS program, “400 Years of the Telescope” (http://www.400years.org/). At the time the problem was discovered, the press chose, not wrongly, to feature an early image of M100, a spiral galaxy, showing clearly a very fuzzy image, seen below.
Image courtesy of Space Telescope Science Institute
What they did not point out (at least in my memory), was the much more significant point that because the images were not sharp points, they were spread over multiple pixels and as a result the distance into space from which the Hubble could collect data was, by accident, almost exactly matched to what was already seen from the ground. As a result, there were no new objects to study, fuzzy or not. This was shown briefly on the PBS show. I had earlier assembled the relevant images, which I have been featuring as my “trademark” on all of my presentation title pages for the last many years.
The first image, shown here, was strategically taken from a large ground-based telescope. It was identified as the darkest point in the sky (field with the smallest number of object with a magnitude as low as 23) over the field of view of the Hubble, as seen from the ground. As can be seen, this image shows only a few objects, none of which look particularly interesting. The intent for the Hubble was to move the lowest magnitude images from the 23 as the lowest visible from the ground to around 28. It was said during the design that if space was considered a 1,000 page book, from the ground we are only able to read page one.
The second image represents one of the longest exposures of the Hubble taken specifically of this darkest region from the ground. This was taken with WF 2 camera. This dramatic photo illustrates the success of the Hubble First Servicing Mission. Nearly every scene in this image has only been imaged by the Hubble and each represents an object that is new to science. And to think, this is the darkest region in space!
It is not well known actually that the terminology WFPC2 (“whif-pick” 2) actually refers to seven different cameras, in two groupings. Three of the cameras make up the Wide Field (WF) format and four of the cameras make up the Planetary Camera (PC). This is illustrated nicely in the following figure.
WFPC2 field-of-view (image courtesy of the Space Telescope Science Institute)
There are four cameras involved with the Planetary Camera, for example, to increase the number of pixels that can be applied to the image. A four-sided pyramidal prism is used to combine the focal planes optically. The pyramid physically rotates to switch between the WF and PC format. The “2” meant it was a second-generation camera.
It was very fortunate that it was always planned to replace the instruments as more advanced detectors became available. One of the biggest problems with these very substantial NASA programs is that the technology that the design is based on is, in this case, over 15 years old by the time it is used. A lot happens in 15 years. This was anticipated with the Hubble and interfaces were designed to allow upgrades over the years.
