Patent ID: 6180955
Filing Date: 2001-01-30
Classification: G01T,G03B

Abstract:
A wavelength selective optical radiation collector, comprising:a hollow body with a diffusely reflective interior surface and with at least one linear slit formed therein defining an aperture for admitting light into the interior of said body;at least one wavelength-selective absorptive filter disposed in said hollow body spanning substantially the entire length of the slit and dividing the interior of said body such that at least approximately 50% of said diffusely reflective interior surface is isolated from said slit by said filter, wherein substantially all of the light admitted through said slit into the interior of said body that returns to said slit has passed through said filter at least twice; anda photodetector in optical communication with said interior of said body;wherein said filter is chosen to be substantially transmissive within a first wavelength band and to be substantially absorptive at a second wavelength band, said filter being substantially non-angle-dependent in its absorptive characteristics.