Lyle H. Taylor

Spatial resolution of imaging noncollinear acousto-optic tunable filters

The spatial resolution limit of noncollinear acousto-optic tunable filters used for imaging with incoherent light is derived based on phase-matching requirements. It is shown that the noncollinear filter can achieve near diffraction limited imaging. This conclusion was verified experimentally.

THE MOVEMENT OF PEOPLE TOWARD LIGHTS

AN EXPERIMENT WAS DESIGNED TO STUDY THE EFFECTS OF PATH ILLUMINATION ON INDIVIDUALS ENCOUNTERING A LEFT-RIGHT DECISION POINT FOR THE FIRST TIME. WHEN EQUIVALENT LEFT- RITH PATHS ARE PRESENTED, TWO-THIRDS OF THE PEOPLE WILL TAKE THE RIGHT PATH UNLESS THE OTHER IS MORE BRIGHTLY LIGHTED. BETTER TO ILLUMINATE THE RIGHT PATH AT LEAST 30 TIMES MORE THAN THE LEFT PATH. THESE SUGGESTIONS COULD INCREASE THE TRAFFIC TO DISPLAYS SUCH AS OFTEN ENCOUNTERED IN MUSEUMS AND RETAIL STORES, AND COULD ALSO BE AN AID IN CONTROLLING EXITING TRAFFIC ON HIGHWAYS. /AUTHOR/

Reduced Spin–Spin Matrix Elements for f4

Reduced matrix elements for all possible two‐body Hermitian operators with spin and orbital rank of two are evaluated for the f4 configuration. Most of the vanishing matrix elements can be explained by simple group‐theoretical selection rules and some can be explained by vanishing coupling coefficients. However, 16 zeros still remain to be explained.

Comparison of acousto-optic tunable filters and acousto-optic dispersive filters for hyperspectral imaging

The acousto-optic tunable filter (AOTF) has a narrow passband and a large angular acceptance angle, which allows for imaging at a given wavelength without having to assemble an image cube, as with grating based imagers. It is also possible to use an acousto-optic dispersive filter (AODF), which has a small acceptance angle and a broad spectral passband to form spatial images similar to the grating imager. Although the processing is more complex, the advantages of the AODF are that pixel registration and temporal fluctuations of the spectra are greatly reduced compared to the AOTF. Both the AOTF and AODF can operate in a birefringent mode, allowing for the use of high efficiency materials such as Tl3AsSe3 (TAS) in the infrared region. They can both be multiplexed to increase the sensitivity, and reduce the spectral fluctuation problem of the AOTF. The AODF can also operate in an isotropic mode, which allows for the use of deflector materials such as Ge. The issues of complexity, fluctuations, efficiency, and multiplexing are compared for AOTFs and AODFs operating in the infrared. A comparison is also made for both systems using TAS, along with AODFs using Ge.

Infrared spectroradiometer design based on an acousto-optic tunable filter

An advanced infrared imaging spectroradiometer for hot targets (100 to 1500 C) has been designed to give real-time spectrally resolved images in the 2-5 micrometers band and to measure irradiances with high accuracy. A tripod-mounted off-axis afocal telescope with a 2.5 degree diagonal field of view directs the input radiation through a Tl3AsSe3 acousto-optic tunable filter (AOTF). The AOTF deflects away from the main beam a narrow spectral bandwidth beam with its central wavelength determined by the acoustic frequency of the AOTF. The AOTF is electronically controlled and can change the wavelength of the deflected beam within approximately 25 microsecond(s) to any other wavelength. The deflected beam is focused onto an 128 X 128 InSb focal plane array which has a frame rate electronically adjustable from 1 to 217 frame/s. With this versatility: 1) key wavelength discriminators of potential targets can be rapidly accessed, 2) the signal-to-noise ration can be improved by increasing the integration time for point targets, and 3) detector saturation can be avoided by reducing the integration time and AOTF diffraction efficiency for very hot targets. Calculations indicate that irradiance measurement errors should usually be less than 1% and often less than 0.1%.

Display Lighting Preferences

A pair of display boxes containing indentical objects displayed under six different lighting conditions were viewed by 134 individual observers. Each observer had to make a forced-choice pair comparison in response to six questions concerning different aspects of the lighted object. Relative rankings of the six lighting conditions are given. The direction from which the light source shines on the object is important with the most preferred to least preferred directions being front, top, and back, respectively. If two source locations are used, the sources should be located in as different directions as possible. Incandescent spot lights were preferred over fluorescent lights, and light intensity was only important for initially attracting attention. It also appears that display lighting is more effective for visually simple objects such as household applicances than for visually complicated objects such as much household furniture.

Fluorescent Lamp Wall Efficiency

If there is optical contact between the phosphor coating and the glass wall of a fluorescent lamp, some of the light will be lost by total internal reflections within the glass wall. This loss decreases the wall efficiency. The theory of this optical contact light loss and a technique for measuring it are described by the authors.