Lightmachinery Inc.

Hubert Jean-Ruel

Ian J Miller

John H Hunter

Edward S Williams

Jesse Dean

John Reid

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.

Multi-pass etalon filter

Conventional etalon based spectrometers have either a limited range of evaluation wavelengths or require continuous scanning of the etalon. Conventional etalon based spectrometers also have limited contrast between the peak transmission of a frequency on resonance and the minimum transmission of a frequency off resonance. An improved optical spectrometer includes a cylindrical lens configured to converge the input beam of light in only one direction, whereby the input beam of light is focused along a focal line. Accordingly, a first etalon receives the input beam of light, and transmits a series of sub-beams, each sub-beam transmitted at a different angle from the normal, and each sub-beam including multiple frequencies based on the FSR, whereby a secondary dispersive element receives each sub-beam, and disperses each sub-beam into individual frequencies. Ideally, a second etalon receives and transmits the sub-beams with increased contrast, and a second thickness of the second etalon is substantially identical to the first thickness of the first etalon.

Etalon based optical spectrometer

A conventional spatial heterodyne spectrometer (SHS) comprises a beam splitter and a pair of diffraction gratings, one in each arm of the SHS. The beam splitter separates an input beam of light into first and second sub-beams for transmission to a respective diffraction grating, and then recombines the diffracted sub-beams for focusing onto a camera. A field widened SHS enables much larger range of input angles of the original beam to be focused onto the camera, so that a broader range of wavelengths may be collected. Increasing the range of wavelengths may be provided by one or more of the following: combining the beam splitter with a field widening prism, making one diffraction grating farther from the beam splitter than the other, and placing a plurality of diffraction gratings in each arm of the SHS.

Spatial heterodyne spectrometer

The invention relates to a multi-resolution optical spectrometer that employs two output lenses of different focal length to provide a broad wavelength range, coarse resolution spectral measurement and a high resolution, lower range spectral measurement. Light dispersed by a virtual image phase array followed by a diffraction grating in two different dispersion orders may be separately focused by the two lenses upon to 2D detector array to provide the two measurements.

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Ottawa, Canada

Hubert Jean-Ruel