Narrow band and wide angle hemispherical interference optical filter
First Claim
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1. A wide acceptance angle filter for transmitting normal incident λ
- optical radiation comprising;
a hemispherically shaped shell being optically transmissive therethrough;
a coating provided on the shell fabricated to transmit incident normal optical radiation of wavelength and smaller;
a photodetector disposed at the radial center of the hemispherically-shaped shell; and
a radiation absorbing surface disposed in the same plane as the photodetector and sized to extend across the diameter of the hemispherically-shaped shell for absorbing nonincident radiation of shorter wavelength than λ
.
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Abstract
An optical interference filter has narrow linewidth and wide acceptance ae and includes a hemisphere coated to provide a narrow bandpass filter at a desired wavelength at normal incidence while other wavelengths at normal incidence are absorbed or reflected. A photodetector placed at the center of the hemisphere detects the desired wavelength only. Other wavelengths that are shorter than the wavelength of the filter are transmitted through the filter to be absorbed by a black absorbing surface around the photodetector. Thus, only the frequency of interest at normal incidence provides a representative signal at the detector.
81 Citations
7 Claims
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1. A wide acceptance angle filter for transmitting normal incident λ
- optical radiation comprising;
a hemispherically shaped shell being optically transmissive therethrough; a coating provided on the shell fabricated to transmit incident normal optical radiation of wavelength and smaller; a photodetector disposed at the radial center of the hemispherically-shaped shell; and a radiation absorbing surface disposed in the same plane as the photodetector and sized to extend across the diameter of the hemispherically-shaped shell for absorbing nonincident radiation of shorter wavelength than λ
. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- optical radiation comprising;
Specification