According to an embodiment of the disclosure, there is provided an electronic device including: an optical element that is fixed and is configured to split incident light reflected from an object into two or more incident light beams traveling along two or more light paths; an optical sensor that is spaced a separation distance from the optical element such that the split incident light beams form an interference area on a light receiving surface and is configured to detect the incident light; and at least one processor configured to determine state information about the object based on similarity between a first spectrum acquired from the detected incident light and at least one reference spectrum.

A hyperspectral imaging system has a processor to receive hyperspectral imaging parameters and produce a series of images to be acquired at a series of retardances at a series of retardance times, a hyperspectral imaging component having an input polarizer to polarize an incoming beam of light, a liquid crystal variable retarder to receive the polarized beam of light and to produce wavelength-dependent polarized light, an output polarizer to receive the wavelength-dependent polarized light and to convert polarization state information into a form detectable as light intensity, a voltage source connected to the liquid crystal variable retarder, and a retardance controller. The retardance controller receives the series of retardances at a series of retardance times and produces a series of voltages at a series of voltage times to apply to the liquid crystal variable retarder. A focal plane array, synchronized with the retardance controller, receives the light in a form detectable as light intensity and converts the light to a series of images.

A spectrometer includes an interferometer having a first interference arm and a second interference arm to produce interference patterns from incident light. At least one of the interference arms includes a series of cascaded optical switches connected by two (or more) waveguides of different lengths. Each optical switch directs the incident light into one waveguide or another, thereby changing the optical path length difference between the first interference arm and the second interference arm. This approach can be extended to multi-mode incident light by placing parallel interferometers together, each of which performs spectroscopy of one single mode in the multi-mode incident light. To maintain the compactness of the spectrometer, adjacent interferometers can share one interference arm.

A common path interferometer is disclosed. The interferometer is arranged to divide an input beam into first and second beam portions directed in opposite directions around a cyclic path to form an interference pattern at a detector. The cyclic path is defined by at least two mirror regions curved in the plane of the cyclic path, such that the interference pattern represents path difference variations between the first and second beam portions. The interferometer further includes an input optic arranged in the beam path before division of the input beam into the beam portions. The input optic is configured to provide convergence to reduce the extent transversely to the plane of the cyclic path of the interference pattern at the detector. The beam and beam portions have different convergence requirements in the plane of, and transverse to the plane of, the cyclic path, which are addressed separately by the mirror regions and the input optic.

A speckle-enhanced discrete Fourier transform spectrometer can include waveguides configured to combine speckle spectroscopy techniques with discrete Fourier transform spectroscopy techniques. A discrete Fourier transform spectrometer section can be a compact, passive, chip-scale optical spectrometer. A speckle spectrometer section can include a multi-mode wave guide. An interference region can be in optical communication with both the discrete Fourier transform spectrometer section and the speckle spectrometer section such that light from both sections interfere in the interference region. A detector can be used to detect light from the interference region for detecting spectral content of light over a large bandwidth at a high resolution.

Systems and methods which provide a compact spectrometer using static Fourier transform interferometer (SFTI) cube configurations, such as are suitable for use with respect to mobile and portable electronic devices, are described. A SFTI cube of embodiments comprises a monolithic dual mirrored wedge beam splitter structure wherein mirrored wedge surfaces provide two reflective mirrors that are slightly tilted away from the orthogonal directions so that the resultant beams of light cross over one another and form an interference pattern. SFTI cube implementations of embodiments facilitate highly compact spectrometer configurations having a wide wavelength range, high resolution, high throughput, and low cost.

The present application provides a spectral phase interference device and system for addressing the problem of low stability and compactness with prior art spectral phase interference devices. In the device or system provided in the present application, the optical element for generating the pulse pair to be measured consists of only a birefringent crystal and the adjustment of two-step phase shift is also completed by only a broadband quarter-wave plate. Therefore, wide application of optical elements such as pulse stretchers, retarders, optical splitters and mirrors as in prior art devices is avoided, thereby significantly simplifying the overall device's structure and resulting in enhanced stability and compactness at the same time.

Compact optical spectrometers are provided to measure optical spectral composition of light.

A method and apparatus used for detecting gaseous chemicals. The method and apparatus use an interferometer to filter received light by wavelength, creating an image only using light with wavelengths that are affected by the presence of a gaseous chemical. A reference image composed of light with wavelengths unaffected by the presence of a gaseous chemical is also created and used as a reference. A gaseous chemical is detected where the ratio of the intensity of the two images changes. Despite the high spectral resolution of the filter, the system can operate with a very wide field of view.

A photo-thermal interferometer for measuring the light absorption of an aerosol or gas comprises a first laser source emitting a laser beam and a beam splitter adapted to divide the laser beam into a probe beam and a reference beam. The interferometer further comprises first optical elements which are adapted to direct the probe beam such that it passes through the aerosol and interferes with the reference beam thereafter thereby causing interference patterns. A detector detects the interference patterns. The interferometer further comprises a second laser source configured to emit a pump beam for transferring energy to the aerosol. Second optical elements are adapted to direct the pump beam such that it overlaps with the probe beam at least partially in the aerosol or gas. At least one of the second optical elements modifying the pump beam is an axicon.