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Biomedical subjects

Yasuhisa Tamagawa

Publications and source records attributed to Yasuhisa Tamagawa.

2 recordsLinked to original sources

Physically based reflectance model utilizing polarization measurement.

A surface bidirectional reflectance distribution function (BRDF) depends on both the optical properties of the material and the microstructure of the surface and appears as combination of these factors. We propose a method for modeling the BRDF based on a separate optical-property (refractive-index) estimation by polarization measurement. Because the BRDF and the refractive index for precisely the same place can be determined, errors cased by individual difference or spatial dependence can be eliminated. Our BRDF model treats the surface as an aggregation of microfacets, and the diffractive effect is negligible because of randomness. An example model of a painted aluminum plate is presented.

Journal Article↗

Configuration of an off-axis three-mirror system focused on compactness and brightness.

We propose a configuration of an off-axis three-mirror system for maximum compactness and brightness. The chief ray is arranged to cross three times inside the system, and the system has a round configuration for compactness. We introduced into the design a ray triangle formed by the reflection points of the chief rays at the mirrors. The ray triangle indicates the size and the brightness of the system. Based on the proposed configuration, a design example of a 4 degrees x 4 degrees field of view is shown. The F-number of the system is 2.2, in close agreement with the estimation from the ray triangle.

Journal Article↗