Each year, Frontiers in Optics has a session entitled “What’s hot in optics”. I thought I’d “liveblog” it (type it up on my computer and post it later) like I did last year; hopefully the comments make sense, considering I got up at 4 a.m. to fly to San Jose.
There were some very interesting things discussed, though I always feel that these talks lack a certain amount of energy. If you’re going to label a session “hot”, I would think that the speakers should bring some enthusiasm to the podium! Then again, people may be a little gloomy due to the economy, which has hit optics like everything else.
4:00: Here I am at the “What’s hot in optics” session. I’m still incredibly tired from my early morning east coast flight; hopefully the speakers can wake me up by “wowing” me. Here we go…
4:01: Chris Schaffer: Seeing the (almost) invisible: using novel nonlinear optical effects for image contrast in biology and medicine
4:03: Cellular specific contrast is necessary in biological imaging: in ordinary imaging, things look the same, i.e. have same refractive index. Nice pic shows difference between blah ordinary imaging (polar bear in a snowstorm) and three-color fluorescence, which can distinguish, nuclei, mitochondria, etc.
4:07: Thick tissue optical scattering results in loss of image contrast. Even if the cells are ‘marked’ with fluorescent dye, the light gets kicked around so much on the way out of the tissue that information is lost.
4:08: Solution: excite fluorescence in a 3-D localized spot; since you know where it was excited, you know where it came from. Nonlinear effects can be isolated to focal region to do this.
4:11: Nice picture, showing that two-photon fluorescence only excited at poitn, while single photon fluorescence excited everywhere in beam path
4:12: Just scan laser focus through sample and record fluorescence intensity as a function of position
4:13: Video of brain image of live rodent looks like B/W intro animation to 50’s horror film!
4:15: 3rd harmonic generation also can be used: 3 infrared photons to ultraviolet photon — very interface sensitive due to Guoy shift?
4:16: Coherent anti-Stokes Raman scattering gives intrinsic chemical contrast; can image lipids in cells (lipids generally hard to image by fluorescence)
4:18: All previous methods mentioned, effects are measured by looking at large changes of color — can we use nonlinear effects which don’t use color changes? How do we see effect if color doesn’t change?
4:20: Use modulation transfer: modulate one beam of a two-beam nonlinear interaction, and look at effect on non-modulated beam. Frequency generation: look for new wavelengths near to the laser pulse.
4:23: Lock-in detection alllows measurement of tiny intensity changes by stim. Raman scattering.
4:25: Lots of biological applications discussed; plenty of measurements of cell behavior which can’t be done with ordinary imaging
4:31: Good question about damage thresholds: nonlinear optics requires “high” power; does it hurt cells? Answer: Nope; power is still lower than thermal damage threshold.
4:32: John Koshel, What’s hot in fabrication, design and instrumentation. Uh oh: fabrication is not one of my strong suits.
4:33: List of lots of FDI-related conferences. I get it; it’s “hot”!
4:34: “International year of astronomy”; Galileoscope for $20 which can be donated to students around the globe. OSA is pushing this now, though Phil Plait has been pushing it for month.
4:35: GalileoMobile Project: 5,000km trip by students around former Inca empire to introduce ‘scopes to this region. I guess Galileoscopes are smaller than Mayan observatories.
4:36: Solar tech. Damn, now he’s describing the Energy/Solar events at FiO!
4:37: Solar potential: 31,000,000 GW!!! (I imagine Doc Brown from Back to the Future shouting it.) Solar resources significantly outweigh energy use.
4:38: less than 0.2% cover of land with 10% efficient cells would provide 2X power of world.
4:39: main pathways: photovoltaics (direct electrical conversion), concentrating solar power (boiling water).
4:39: Lots of different technologies for concentrating, which require tracking.
4:40: Big range of PV technologies. 30% to 40% efficiency during the last decade. Best cells are very expensive.
4:40: Design of concentrators. Focus light into smaller region of PV. Standard method: Fresnel lenses.
4:42: Free-form concentrators: no rotational symmetry – concentration of 1000 suns on solar cell! Non-imaging devices. Making uniform irradiance on solar cell improves efficiency dramatically.
4:44: Cool earth solar technology: balloon-like solar concentrator, 2m across
4:45: Fabrication. Lots of factors reduce efficiency, and tolerances of system has to be shared amongst them. “Cheap” is the operative word.
4:47: Testing. Testing of optics, testing of solar panels. Surface texture is crucial for good light collection. Rough surface collects more. A single cell can have many textures. 4 parameters characterize the optical efficiency.
4:49: David Brady: OSA Information Acquisition, processing and display division.
4:51: What’s hot: compressive measurement, holography
4:52: Oddly, non-imaging optics used for new imaging techniques!
4:53: Compression of data after measurement implies that there is redundancy in measurement process. We should be able to image “more” with less measurements.
4:53: Compressive imaging: PSF engineering w/ nonlinear reconstruction can overcome the limitation of pixel-limited resolution.
4:56: 3D fluorescence superresolution imaging using a double helix points spread function: maximizes Fisher information. PSF spins as a function of defocus: ‘encoding’ in PSF.
4:57: Image reconstruction of vasculature specimen from sparse cone-beam ct data. Reconstruction of CT images done with a factor of 6 less data, but with almost no image degradation.
4:58: Compressive imaging: use apriori knowedge to reduce measurements. Combined with nonlinear processing, gives good resolution.
4:59: Holography. 2009 has major digital holographic technology advances.
5:00: Why don’t we use lasers in more applications? Flashes, illumination? He doesn’t know. Eventually they may appear in more imaging applications.
5:01: Zebra Imaging manufacturing display holograms for defense, other applications.
5:02: Holographic memory: GE announces 0.5 TB capacity holographic disk.
5:02: Compressive holography? Holograms give 3D perspective, but tomography assumed to be needed for full 3D image. But can reconstruct truly 3D objects from single hologram.
5:05: Questions: Are compressive techniques more or less sensitive to noise than traditional techniques? Less sensitive to noise, according to Brady.
5:05: Okay, I’m going to skip the last talk and go rest up before boozing and socializing…