Optical filter for spectroscopic measurement and method of producing the optical filter

DETAILED DESCRIPTION The present invention provides a rotating dichroic filter for spectroscopic measurement wherein the cost of the filter is approximately 100 times less than conventional rotating dichroic filters.
This is accomplished by first relaxing the specifications of the filter and compensating for the relaxation of filter specifications through more intensive signal processing steps.
In addition, the filter is constructed in a manner which allows for easier production.
The filter constructed in accordance with the present invention allows from 10 to 100 times as much light to pass while maintaining the necessary precision through signal processing.
One aspect of the present invention involves a method of manufacturing an optical filter.
The method involves a number of steps.
An optical substrate is provided having a top surface and a bottom surface, and layers of optical coating are deposited on the top surface such that the layers vary in thickness across the top of the substrate in a first direction.
The thickness of the layers is substantially constant in a second direction substantially perpendicular to the first direction.
In one embodiment, the method further involves creating a mounting hole in the center of the substrate.
In addition, an opaque strip along at least a portion of the substrate is deposited in one embodiment.
Another aspect of the present invention involves an optical filter.
The optical filter has a substrate having a top surface and a bottom surface.
The filter also has a plurality of optical coatings deposited on the top surface of the substrate such that the coatings vary in thickness in a first direction across the top surface.
The coatings are substantially constant in thickness across the top surface in a second direction substantially perpendicular to the first direction.
Another aspect of the present invention comprises an optical filter having a generally circular substrate.
Layers of optical coatings deposited on the substrate provide a non-imaging interferometer wherein approximately one-half of light incident upon the coatings passes through the coatings over the entire surface of the substrate