What is Nonimaging Optics?Nonimaging optics is a field that deals with the optimal transfer of lightbetween a source distribution and a target distribution. The most common use ofnonimaging optics is achieving maximal concentration of light. As detectornoise or thermal radiation generally depends on the target area, one sees thatdetector systems and solar energy applications can benefit. Imaging systemshave large aberrations which prevent ideal (or maximal) concentration.
Other applications use nonimaging optics to design illumination systems where aconstant irradiance can be achieved on a distant target using novel types oftailored reflectors. Also, concentrators for solar pumped lasers can beoptimized to better the pump power absorption distribution inside a solid statelaser crystal, such as Nd:YAG or Nd:GSSG.
In order to keep pages small, we describe our various projects using adifferent webpage for each. Below is a description of the 50,000 sunsexperiment. After that, hypertext cues will transfer you to additional webpagesexplaining our other projects.
(for more information: http://hep.uchicago.edu/solar/ )
NON-IMAGING OPTICAL TECHNIQUES
A variety of optical techniques have been developed over the years forexperimental intervention into living specimens. These techniques have theadvantage over more traditional experimental approaches, such asmicromanipulation, that there is less chance of unwanted collateral damage andthat probes can reach deep within specimens (provided the specimens arereasonably transparent).
Laser microsurgery.Some years ago we developed cell ablation system for use with embryos, inparticular C. elegans (Sulston and White, 1980 Dev Biol 78(2):577). Derivativesof this system are now widely used in many laboratories to study inductivecell-cell interactions in developing embryos. It was found that the optimumstrategy for a cell ablation system that has high precision yet produces aminimum amount of collateral damage, was to use a pulsed source of around 1nsduration and a wavelength around 440nm. A nitrogen laser pumping a dye laser iscurrently the most favored irradiation source.
Fluorescent recovery after photobleaching.This technique has been used to measure intracellular movements such as thediffusion of proteins in membranes (Ladha et al., 1997 J Cell Sci 1997 110(9):1041) and the movements of microtubules during mitosis (Centonze and Borisy,1991 J Cell Sci 100( Pt 1):205). Fluorescently-labeled target structures areilluminated by a high-intensity patterned source (typically a laserilluminating a line) for a short time in order to produce a bleached pattern.The structures are then imaged using low levels of irradiation to visualize thedynamic changes in the bleached pattern. From these data diffusion rates ormovement velocities can be calculated.
Photoactivation of caged compounds.Several fluorophores (fluorescein, rhodamine green) and bioactive agents(calcium, ATP, neurotransmitters, calmodulin inhibitors) can be rendered inertby the addition of a molecular cage. The cage is designed such that it can bephotolyzed by short-wavelength irradiation thereby releasing the fluorophore orbioactive agent (Theriot and Mitchison, 1992 J. Cell Biol. 119:367).Irradiation by a focused, transient beam of light allows the bioactive agent(e.g. a signaling molecule) to be released within a cell with high spatial andtemporal precision. This technique is becoming a very powerful experimentaltool for the cell and neuro biologist, particularly as more caged molecules arebecoming available. Most currently favored caging techniques requireirradiation at around 320nm for photolysis of the cage. There is considerableinterest in the possibilities for multiphoton uncaging (Denk, 1994 PNAS 91(14):6629). As in the case of multiphoton excitation fluorescence imaging,multiphoton events only occur in significant abundance within the focal volumeof an objective which is directing light derived from a high-peak power lasersource into the sample. This gives the technique exquisite spatial localizationas photolysis (and hence the release of a bioactive agent) will only occur inthe focal volume of the objective.
Optical Trapping.Small particles (0.5m - 10m) may be trapped by radiation pressure in the focalvolume of a high-intensity, focussed beam of light. This technique may be usedto move small cells or sub-cellular organelles around at will by the use of aguided, focussed beam (Askin et al., 1987 Nature 330: 769). Ingenious systems,using optical trapping in conjunction with interferometry to measure smalldisplacements, have been used to measure the force exerted by individual motorproteins (Kojima et al., 1997 Biophys J 73(4):2012). Optical trapping offers avariety of experimental possibilities. For example, a bead coated with anvolume of a high-intensity, focussed beam of light. This technique may be usedto move small cells or sub-cellular organelles around at will by the use of aguided, focussed beam (Askin et al., 1987 Nature 330: 769). Ingenious systems,using optical trapping in conjunction with interferometry to measure smalldisplacements, have been used to measure the force exerted by individual motorproteins (Kojima et al., 1997 Biophys J 73(4):2012). Optical trapping offers avariety of experimental possibilities. For example, a bead coated with animmobilized caged bioactive probe could be inserted into a tissue or even acell and moved around to a strategic location by an optical trapping system.The cage could then be photolyzed by multiphoton uncaging. This would provide anon-diffusable localization of the bioactive probe at a time and placedetermined by the experimenter. The optimal wavelengths for optical trappingare in the 800nm -1100nm range. Typically powers of around 100mw are used.
for more information:
Other applications use nonimaging optics to design illumination systems where aconstant irradiance can be achieved on a distant target using novel types oftailored reflectors. Also, concentrators for solar pumped lasers can beoptimized to better the pump power absorption distribution inside a solid statelaser crystal, such as Nd:YAG or Nd:GSSG.
In order to keep pages small, we describe our various projects using adifferent webpage for each. Below is a description of the 50,000 sunsexperiment. After that, hypertext cues will transfer you to additional webpagesexplaining our other projects.
(for more information: http://hep.uchicago.edu/solar/ )
NON-IMAGING OPTICAL TECHNIQUES
A variety of optical techniques have been developed over the years forexperimental intervention into living specimens. These techniques have theadvantage over more traditional experimental approaches, such asmicromanipulation, that there is less chance of unwanted collateral damage andthat probes can reach deep within specimens (provided the specimens arereasonably transparent).
Laser microsurgery.Some years ago we developed cell ablation system for use with embryos, inparticular C. elegans (Sulston and White, 1980 Dev Biol 78(2):577). Derivativesof this system are now widely used in many laboratories to study inductivecell-cell interactions in developing embryos. It was found that the optimumstrategy for a cell ablation system that has high precision yet produces aminimum amount of collateral damage, was to use a pulsed source of around 1nsduration and a wavelength around 440nm. A nitrogen laser pumping a dye laser iscurrently the most favored irradiation source.
Fluorescent recovery after photobleaching.This technique has been used to measure intracellular movements such as thediffusion of proteins in membranes (Ladha et al., 1997 J Cell Sci 1997 110(9):1041) and the movements of microtubules during mitosis (Centonze and Borisy,1991 J Cell Sci 100( Pt 1):205). Fluorescently-labeled target structures areilluminated by a high-intensity patterned source (typically a laserilluminating a line) for a short time in order to produce a bleached pattern.The structures are then imaged using low levels of irradiation to visualize thedynamic changes in the bleached pattern. From these data diffusion rates ormovement velocities can be calculated.
Photoactivation of caged compounds.Several fluorophores (fluorescein, rhodamine green) and bioactive agents(calcium, ATP, neurotransmitters, calmodulin inhibitors) can be rendered inertby the addition of a molecular cage. The cage is designed such that it can bephotolyzed by short-wavelength irradiation thereby releasing the fluorophore orbioactive agent (Theriot and Mitchison, 1992 J. Cell Biol. 119:367).Irradiation by a focused, transient beam of light allows the bioactive agent(e.g. a signaling molecule) to be released within a cell with high spatial andtemporal precision. This technique is becoming a very powerful experimentaltool for the cell and neuro biologist, particularly as more caged molecules arebecoming available. Most currently favored caging techniques requireirradiation at around 320nm for photolysis of the cage. There is considerableinterest in the possibilities for multiphoton uncaging (Denk, 1994 PNAS 91(14):6629). As in the case of multiphoton excitation fluorescence imaging,multiphoton events only occur in significant abundance within the focal volumeof an objective which is directing light derived from a high-peak power lasersource into the sample. This gives the technique exquisite spatial localizationas photolysis (and hence the release of a bioactive agent) will only occur inthe focal volume of the objective.
Optical Trapping.Small particles (0.5m - 10m) may be trapped by radiation pressure in the focalvolume of a high-intensity, focussed beam of light. This technique may be usedto move small cells or sub-cellular organelles around at will by the use of aguided, focussed beam (Askin et al., 1987 Nature 330: 769). Ingenious systems,using optical trapping in conjunction with interferometry to measure smalldisplacements, have been used to measure the force exerted by individual motorproteins (Kojima et al., 1997 Biophys J 73(4):2012). Optical trapping offers avariety of experimental possibilities. For example, a bead coated with anvolume of a high-intensity, focussed beam of light. This technique may be usedto move small cells or sub-cellular organelles around at will by the use of aguided, focussed beam (Askin et al., 1987 Nature 330: 769). Ingenious systems,using optical trapping in conjunction with interferometry to measure smalldisplacements, have been used to measure the force exerted by individual motorproteins (Kojima et al., 1997 Biophys J 73(4):2012). Optical trapping offers avariety of experimental possibilities. For example, a bead coated with animmobilized caged bioactive probe could be inserted into a tissue or even acell and moved around to a strategic location by an optical trapping system.The cage could then be photolyzed by multiphoton uncaging. This would provide anon-diffusable localization of the bioactive probe at a time and placedetermined by the experimenter. The optimal wavelengths for optical trappingare in the 800nm -1100nm range. Typically powers of around 100mw are used.
for more information:
