Idle Diffractions

Report from the OFC/NFOEC 2010 Plenary Session

(OK, today I’m distracted; see the origins of K-I-S-S at the bottom of this post.)

I attended the plenary session at OSA’s OFC/NFOEC conference in sunny San Diego this morning – I’m overlooking the harbor now.  It has been at least five and perhaps even seven years since I was last here at OFC.  As with most good plenary sessions, I came away with all sorts of trivia and even some perspective – where to begin?

I will save the distraction for a moment and see if I can fill out this post with facts of the past, present, and future as it relates to the rise of global and personal communications.  Some of the numbers are staggering.  I expect many readers were caught up in the frenzy of telecom and that many have not looked back since the crash.  My recollections are that we designed our first WDM (wavelength division multiplexer) for a government research center in 1997, based on a large glass prism.  Shortly thereafter, I found myself writing an 80-page proposal to the ATP program for a few million dollars to advance free-space optics modeling.  In spite of having nearly no idea what I was writing about, as this was the early days, and the fact that I wrote the proposal alone in a hotel over a 60-hour sleepless stretch (haven’t done that again), we won.  Following this, I had the clever idea that many people would be interested in glass prototype micro-optics, and so we bought an optics shop in the U.S. that made endoscopes.  With that, we were on the train.  I spent the next three years on the road (40 weeks a year) and yes, we even exhibited at OFC in 2001, I believe. Our engineering group saw our telecom design business grow from that first job in 1997 to 30% of our business at the time of the crash, in June 2001 as I recall.  Well, that was then.

In touring the remains of the industry at the show today, I was telling my colleague that it’s like the telecom giants woke up one morning, looked around, and stepped on all the ants that were swarming around them.  Today I heard three names consistently: Verizon, ATT (yes, they seem to be back), and Alcatel.  And apparently JDSU is hiring.  The displays are old and tired, there are a lot of empty spaces, and in general, I’d say the status quo prevailed into the end.

But here are some of the plenary numbers.  When ARPAnet was invented in 1963, it connected UCLA, UCSB, Stanford, and the University of Utah.  In 1969, as I’m entering high school, the first DNS was assigned.  Today there are 500,000,000 of those (assuming DNS is a noun, I didn’t look up what it means). If that doesn’t work, that number is also attributed to the number of Internet nodes.  In 1980, as I exited graduate school, there were 0 mobile phones.  Today, there are 2,500,000,000 of those.  I heard in the hall today, or was it yesterday, FLICKR (a photo upload site?, don’t know, haven’t been there, yet) had its 1,000,000,000th transfer, at the same time the current run rate is 1,000,000,000/year. Now that’s a growth rate. I don’t think they get $0.01, but, if they did…. 

An interesting plot showed that in the early 60’s the world had 2.3 billion people, and if I understood the plot, a significant percentage of them lived in “developed” countries.  In 2013, there will still be about 2 billion people in the developed countries, and 6 billion in the developing countries.  The growth rate for the developed countries is flat. 

You’ve seen hockey stick growth projections.  But have you ever seen it actually occur? I may get the units wrong here – in 1993, the Internet appears to the average techie, defining the start of data flow.  By 2000, 6,200,000,000 GB of data is transferring per year, or per day/hour/minute/sec, not sure which.  (Note: GB already has 9 zeroes).  In 2011, we’re going to see a data rate of 1,800,000,000,000 GB.  Now that is a hockey stick.  Based on conservative projections, the data rate in 2020 will be in units of Petabits/sec (those come after Terabits, which come after Gigabits, or GB).  According to the third speaker in the plenary session, if we don’t rethink the architecture before 2020 (that’s in 10 years), it will require the entire output of a nuclear power plant (a really big number of Kw) to drive the routers needed, based on current technology. No wonder the word energy efficiency comes up.

I do recall when I last paid attention, the Holy Grail was 100Gbit data rates.  Many predicted it could not happen.  But the big announcement (OK, maybe just a big announcement) was that a 100Gbit routing would be brought online this year.  Apparently “coherent technology” has solved the challenge of transferring at these data rates without starting over.  So now they’re talking of 100Gbit routing to small companies before I retire, and to my home shortly thereafter.  So, what I think will be fun is reflected in a talk I heard in early 2000 by a telecom executive. He was having fun putting an early webcam on his dog, with a wireless unit, and then during the day turning it on to see where the doggie was.  His thinking was, eventually (which appears to be soon), you enter a GPS coordinate somewhere in the world, and you are routed to the nearest webcam from which you can view life, live – sounds neat.  I can imagine the end of travel, or will it be the beginning of armchair travel.  Once you have your immersive, full surround 3-D TV, you sign up for the trip down the Amazon consisting of a live feed to a surround of cameras on a boat outfitted for the purpose – could be interesting.

OK, before exceeding the space here on this blog post, the distraction I referred to earlier.  A speaker attributed the term Keep It Simple Stupid to one David S. Isenberg.  So, who could resist, I Googled (a term still not in my spell checker).  The answer is no, it was not him, but if you’re into telecom, you should check him out at www.isen.com.  You will find there, at least today, the following interesting graphic.

It turns out the right answer is Clarence “Kelly” Johnson, 40 years with the Lockheed Skunk Works – courtesy of Wikipedia.  Also worth a short visit if you’re a Skunk Works fan. 

NASA’s Wide-field Infrared Survey Explorer (WISE)

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-Learned J, 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”.

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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

 -Mark Kahan

Connections: before optical glass there was …a furnace?

A few years ago, I came to the somewhat soft conclusion that the world of optical design can be defined to have really started in 1886, when Schott, Abbe, and Zeiss got together and, with the help of new glass formulations, started to design optics, particularly for microscopes.  But then at last fall’s UK Optical Design Meeting, Jon Maxwell, formerly of Imperial College, handed me a paper on one William Vernon Harcourt (1789-1871) and said I “might find it interesting.”  He was right – and it changed my opinion of the origins of optical design.

James Burke’s documentaries, called Connections, have always been very impressive to me, because Burke did a wonderful job explaining how seemingly unconnected scientific discoveries and other historical events build on one another to bring about technological advances. Connections is available on DVD, and some episodes are also on YouTube.

I mention Connections because Harcourt made optical glass 50 years before Schott, but he did it not because he had a passion for glass, but because he had a passion for furnaces.  Harcourt had made essentially the world’s hottest furnace, and there was then a question of what to do with it. At this point, Michael Faraday (1791-1867) apparently broached the idea of using the furnace to make optical glass. Later, G.G. Stokes (1819-1903) moved the ball forward by encouraging Harcourt to try more experiments with optical glasses (at this point Faraday had shifted his focus to electricity). In the 1830s, as science was emerging really for the first time, there was a small group in England that formed under the affiliation of the British Association for the Advancement of Science, of which Harcourt was a founding member.  If you’re interested in finding out more about these connections, there’s a nice article by E. Scott Barr in the first volume of Applied Optics, where one finds a story on Stokes.

 
Example of furnace for the manufacture of optical glass, by Henry Bessemer, circa 1850. Bessemer presented a paper on mass production of steel to the British Association for the Advancement of Science in 1856. Image from Sir Henry Bessemer, F.R.S., An Autobiography, 1905.

For more information:
E. Scott Barr, “Men and Milestones in Optics,” Applied Optics, Vol. 1, No. 1, 69-73 (1962).

M. Cable and J.W. Smedley, “William Vernon Harcourt: pioneer glass scientist and founder of the British Association,” Glass Technology, Vol. 33, 92-97 (1992).