I thought I’d experiment and try liveblogging a session about What’s Hot in Optics Today? at the OSA Annual Meeting. This was in fact one of the first sessions, and seemed interesting enough. Unfortunately, I couldn’t liveblog, because I didn’t have wireless access in the chamber! I wrote up my real-time comments in MS Word, and post them, slightly edited for clarity, below.
To summarize briefly: the division chairs (or their representatives) of the different technical groups of the meeting each gave a presentation concerning exciting research in their area. The different talks were:
- Chris Schaffer, Frontiers in Biomedical Optics: Nanometer scale optical imaging inside cells. Typically, one can only resolve (i.e. distinguish) features of an object which are separated by a size larger than half a wavelength. Unfortunately, the internal structure of cells contains features which are much smaller than a wavelength. The talk described very clever techniques for beating the diffraction limit.
- Daphne Bavelier, What’s Hot in Vision and Color: Pwning normal vision. It turns out that playing fast-paced, first-person shooter video games is actually a benefit to vision! This talk discussed research into the effects of video gaming on various aspects of vision.
- Juerg Leuthold, What’s Hot in Photonics and Opto-Electronics. One of the current big challenges of fiber-optic communications is increasing the amount of data that can be transferred over a fiber-optic cable. This talk discussed different techniques for improving this bit transfer rate, anticipating the next generation of internet connections.
- R. John Koshel, What’s Hot in Fabrication, Design and Instrumentation: The Optics in Energy and Imaging Systems. Modern optical systems need to be efficient, both in collecting light (e.g. for use in solar cells) and in transmitting light (e.g. for making highly efficient light bulbs). This talk discussed strategies for developing this next generation of optical technology.
The actual talks are supposed to be put online on this page for public consumption; in the meantime, you can read my ‘liveblogging’ below!
4:00: People are still shuffling in, and the screens are dark. I’m guessing they’re having the usual ‘technical difficulties’ which hound every conference. Whoops, they just got something powered up.
4:04: I don’t see any of my colleagues here, yet. I guess I’m the only one who doesn’t know what’s hot in optics?
4:05: David Finehoff (?), chair of sessions, gives a brief introduction, Chris Schaffer begins to talk about Bio-medical optics. He’s going to talk about one specific application, rather than a broad overview. He wants to discuss imaging on the scale of 10’s of nm, even within live cells. Fluorescence labeling allows identification of specific bio structures. Mention of chemistry nobel for ‘green fluorescent protein’.
4:10: Rayleigh criterion limits resolution to ½ a wavelength for conventional imaging. This can be beat by recording sub-diffraction limited volumes sequentially. Use time as additional parameter to get spatial resolution. Near-field isn’t great: fluorescence saturation, stimulated emission, and single-molecule methods are better.
4:13: STED: excite fluorescence with a focused laser spot (1/4 wavelength); use STim Emission in donut mode to force outer molecules to Deplete. Left with a 20 nm emission spot. Pretty pictures of a neural process!
4:16: Single molecule measurements: single fluorescent emitter resolution is different from resolving two molecules.
4:18: If we can image molecules sequentially, we can avoid the problem of resolving many molecules. Seems like a lot of work.
4:19: Photoswitchable proteins activate w/ one wavelength and deactivate w/ another. But how do you activate only one? Shine w/ dim light, so only a few molecules get turned on at a time, do this many times to build up a big pic of all the individual molecules. More pretty pictures!
4:23: Can be done w/ two colors, to make pics of different structures.
4:24: By using astigmatism of light beam, one can do three-dimensional imaging. Astigmatism is usually considered an imperfection in an optical system, but here that distance-dependent error allows one to pinpoint the z-position of molecules. B. Huang, et al. Science 219, 810 (2008).
4:28: Method takes time, and has so far been done with mostly dead cells; Betzig’s group used 24 hour data acquisition. Betzig can now do live cell imaging. H. Shroff, Nature Methods (2008).
4:30: Lots of acronyms: PALM, STORM, FPALM (stochastic optical reconstruction microscopy). Chris said he ‘literally’ stole figures from various research groups. Did he sneak into their labs and hack into their computer systems, I wonder?
4:31: Question about resolution. Is finding the centroid of a diffraction limited spot really ‘resolving’ it? How does one turn one molecule ‘off’ and the other ‘on’? Done stochastically, i.e. randomly: turn on a low density, so it’s incredibly unlikely that any two adjacent molecules are on at the same time. I’ll have to blog about this technique in more detail later.
4:34: Daphne Bavelier starts on what’s hot in vision in color. “Pwning normal vision”. An academic description of what ‘pwning’ is. Talk will be about video game players having superior vision to non-video players. A nice video of FPS game, which baffled lots of attendees, I think. Average player is 35 years old – yes! I’m 37, and not necessarily an old fogie!
4:37: Objects of attention: number of ‘object’ that can be tracked ‘attentionally’. Typically about 4. Moving sad faces turn to happy faces – try and track them! Non-video gamers fail at 4, video gamers at about 7.
4:41: Attention over space. Try and find relevant objects in a busy image. Gamers can spot things at bigger eccentricity angles than non-gamers, even at angles that they normally don’t see things in games!
4:44: Insurance companies may give breaks for drivers who play action games!
4:45: Attention over time. Efficiency of visual attention over time. Look for a white letter in a fast display of letters, as well as a black ‘x’. If the ‘x’ appears too soon after the white letter, people will miss it. An ‘attentional blink’. Video game players rock on this, too!
4:46: Is it the gaming, or self-selection (i.e. people who are good at games play them more)? Training studies: half male, half female. Students are paid to play action/non-action games for 10 hours, with a pre-test and a post-test. Action gamers improved, while non-action gamers didn’t.
4:50: But what about vision? Hypothesis: action game playing changes spatial and temporal resolution?
4:51: Tested contrast sensitivity: put a Gabor patch in one of two very rapidly displayed images; can the viewers spot it? Video gamers have better contrast sensitivity!
4:52: Big picture: video games correct the optics of the cortex, just like glasses correct the optics of the eye. In conclusion, I need to go home and play some more Half-Life 2.
4:55: Question: Do the benefits last? Apparently research shows that the benefits last, even months later.
4:59: J. Leuthold talks about emerging trends in the field of the photonics division.
5:00: Photovoltaics. Basically, solar cells. Holographic mirrors are used to map light from parts of surface into PV cell material. Also, attempts to perform ‘direct conversion of solar energy to hydrogen’. A little poorly phrased: I think you need water, too!
5:03: Photonic communications. Lots of focus on development of components for 100 Gb/s ethernet. Silicon optics will be important. Polymer optics will be important. Lots of other things will be important in optical communications.
5:06: New modulation formats. New solutions for dispersion compensation in optical fibers. Split up signal into a bunch of low bandwidth signals which therefore have little dispersion. Also: generalize from ‘on-off’ bits to bits in the complex plane.
5:08: Transmission of 16.4 Tbits/s over 2,550km using polarization division multiplexed quadrature phase-shift keying. This is a fast, fast, rate of data transmission over standard fiber.
5:10: 25.6 Tb/s over 240 km! Dispersion, which gets worse over distance, is apparently the limiting factor in these experiments. Faster data rate = higher bandwidth = more dispersion = limit to transmission distance.
5:12: 10×121.9 Gb/s over 1000 km by using a complex 8-bit system. Also, 17 Tb/s over 662 km using other modulation formats.
5:13: Phase-sensitive waveform sampling at 40 GSymbols/s. A bit unclear what is going on, but it involves using nonlinear signals.
5:15: I’m getting a little lost. Unlike the other talks so far, the speaker is a little unclear, there are many, many examples and a lot of knowledge is being assumed of the audience. In short, there are a lot of nifty new devices which result in high data transfer rates, high levels of multiplexing/demultiplexing, etc.
5:18: Bending loss is a problem. A bent fiber will violate the total internal reflection which makes it work. New fiber designs with rings of air or holes in the fiber have very little loss when bent.
5:20: Also, single mode fibers which have very large cores have been developed. A single mode fiber typically carries its energy in a very narrow region, which means that it can’t carry that much power without going nonlinear or breaking down. Making the core bigger allows more power.
5:22: No questions. I’m not surprised. There was a lot of rapidly described stuff.
5:23: R. John Koshel, What’s hot in fabrication, design and instrumentation: the optics in energy and imaging systems.
5:25: Optics for imaging systems. Two ways: Image processing incorporated into the design of system. Optical components that include the image processing.
5:26: Wavefront coding: what is it? Use a phase mask to encode image, and use computer to deconvolve image. Use a known blur function; knowing the blur function allows one to compensate for depth of field.
5:28: Interesting: A non-reversing mirror. Shows a picture of a mirror image, with words NOT in reverse. Such asymmetric mirrors could remove blind spots in car mirrors.
5:31: Simultaneous multiple surface design with 4 skew rays. Can be used to design an imaging system by geometrical optics of skew rays. Demonstrates the design in the application of reducing the distance between a projector and a screen. By adding an optic, the projector can be 21 cm from the wall, and produce a 100’’ image size!
5:34: Optics for energy. Energy costs are increasing dramatically. Look at solar power generation, and high efficiency solid-state lighting. Solar power use is going up: 606 k MW in 2007, 426 through June of 2008.
5:36: Solar generation methods. Solar thermal: heat material to drive turbine. Solar PV: Generate electricity from light. Up to 40% efficient, at this stage.
5:37: Images of interesting solar concentrators currently in use.
5:38: Fresnel lens focuses to secondary lens, which focuses onto LED chip.
5:40: Also need designs in transmitting light efficiently and uniformly. The SMS method is used to make such designs. Applied to car headlights: ordinary ones are 30-40% efficient, new models are 70-80%.
5:41: Okay, I’ve had enough! I’m heading to the reception at 6:00 to start drinking.