Photopic detector system and filter therefor
Assignee3M Innovative Properties Company
InventorsTakashi Harada, Kazuhiko Mizuno, John A. Wheatley, Timothy J. Nevitt, Andrew J. Ouderkirk
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Abstract
A detector system, filter therefor, and method of making same is disclosed. The filter includes an interference element having a reflection band disposed primarily in the near infrared, and having a high transmission over most of the visible region. The filter also includes an absorptive element that absorbs light non-uniformly over the visible region. The filter when combined with a semiconductor photodiode or other suitable detector yields a detector system whose spectral responsivity closely matches the visual response of the human eye.
Claims29
A filter suitable for use with a detector, the filter comprising:
- an interference element that substantially reflects normally incident light over a band of near-infrared wavelengths and that substantially transmits normally incident light over visible wavelengths;
- and
- an absorptive element that absorbs light non-uniformly over visible wavelengths, the absorptive element comprising a colorant dispersed in a polymeric matrix;
- wherein the filter when combined with the detector yields a detector system whose relative response approximates a visual response of the human eye.
A method of making a filter suitable for use with a detector, the method comprising:
- providing an interference element that reflects normally incident light over a band of near-infrared wavelengths and substantially transmits normally incident light over visible wavelengths;
- loading an absorptive colorant that absorbs light non-uniformly over visible wavelengths into a resin;
- shaping the resin to form an absorptive element;
- and
- combining the interference element and the absorptive element to provide the filter;
- wherein the filter when combined with the detector yields a detector system whose relative response for normally incident light approximates a visual response of the human eye.
Dependencies are inferred from the claim text.