Method and apparatus using volume holographic wavelength blockers
First Claim
1. A volume holographic wavelength blocking filter assembly comprising:
- a plurality of reflective volume holographic gratings having a cumulative optical density of at least two, each reflective volume holographic grating havinga distinct slant angle; and
a distinct grating spacing,wherein the plurality of reflective volume holographic gratings produce a filtered optical signal when disposed in a path of an optical signal.
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Accused Products
Abstract
The invention disclosed here teaches methods to fabricate and utilize a non-dispersive holographic wavelength blocker. The invention enables the observation of the Raman signal near the excitation wavelength (˜9 cm−1) with the compactness of standard thin film/holographic notch filter. The novelty is contacting several individual volume holographic blocking notch filter (VHBF) to form one high optical density blocking filter without creating spurious multiple diffractions that degrade the filter performance. Such ultra-narrow-band VHBF can be used in existing compact Raman instruments and thus will help bring high-end research to a greater number of users at a lower cost.
176 Citations
31 Claims
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1. A volume holographic wavelength blocking filter assembly comprising:
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a plurality of reflective volume holographic gratings having a cumulative optical density of at least two, each reflective volume holographic grating having a distinct slant angle; and a distinct grating spacing, wherein the plurality of reflective volume holographic gratings produce a filtered optical signal when disposed in a path of an optical signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An apparatus for Raman spectroscopy, the apparatus comprising:
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a laser, an output of the laser being directed toward physical matter to cause Raman scattering, thereby producing a Raman signal; a plurality of reflective volume holographic gratings having a cumulative optical density of at least two, each reflective volume holographic grating having a distinct slant angle; and a distinct grating spacing, wherein the plurality of reflective volume holographic gratings produces a filtered Raman signal when disposed in a path of a Raman signal; the apparatus further comprising an optical spectrometer disposed in a path of the Raman signal to measure a spectrum of the Raman signal and to generate a detection signal; and a microprocessor to receive the detection signal to determine properties of the physical matter. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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Specification