Back to results
US 11,239,626 B2Granted
Multi-pass etalon filter
AssigneeLightMachinery Inc.
InventorsJohn H. Hunter, Hubert Jean-Ruel, Ian J. Miller
Life of this patent
Estimating the term…
Abstract
The invention relates to a multi-pass etalon-based optical filter in which input light once reflected from the etalon is returned back to the etalon for a second reflection to enhance etalon contrast. The external mirror may be tilted relative to the etalon so that two planes of incidence are orthogonal. The multi-pass etalon-based optical filter may be used to clean scattered light from an excitation wavelength in Raman and Brillouin spectroscopy.
Claims18
An optical filter comprising:
- a first Fabry-Perot (FP) etalon disposed in an optical path of input light and configured to split the input light into transmitted light comprising a target wavelength and first reflected light where the target wavelength is suppressed;
- and, a reflector disposed to receive the first reflected light, and to reflect the first reflected light back toward the first FP etalon as returned light for a second reflection therefrom, and an output port disposed to receive output light from the first FP etalon, wherein the output port is characterized by a numerical aperture that is smaller than 0.2 and wherein the output light is characterized by a beam divergence angle, and wherein the output port is configured to have an acceptance angle that is at least 10% smaller than the beam divergence angle.
A method for filtering out a target wavelength from input light, comprising:
- directing the input light at a Fabry-Perot (FP) etalon at a first angle of incidence angle to obtain first etalon-reflected light wherein the target wavelength is partially suppressed;
- and, returning at least a portion of the first etalon-reflected light back toward the FP etalon as returned light, so that the returned light is incident upon the FP etalon at a second angle of incidence to obtain second etalon-reflected light where the target wavelength is further suppressed, wherein the second angle of incidence is substantially equal to the first angle of incidence angle in magnitude;
- an output port disposed to receive output light from the FP etalon, wherein the output port is characterized by a numerical aperture that is smaller than 0.2 and wherein the output light is characterized by a beam divergence angle, and wherein the output port is configured to have an acceptance angle that is at least 10% smaller than the beam divergence angle.
Dependencies are inferred from the claim text.