A method of calibrating a spectrophotometer comprising a flash lamp. The method comprises receiving light from the flash lamp at a monochromator of the spectrometer, wherein the flash lamp is a short arc noble gas flash lamp with transverse or axially aligned electrodes; configuring the monochromator to progressively transmit the received light at each of a plurality wavelengths of a selected range of wavelengths, wherein the range of wavelengths is associated with a wavelength feature according to a known spectral profile of the flash lamp, and wherein the wavelength feature is a self-absorption feature; and determining a spectrum of the flash lamp, wherein the spectrum comprises a corresponding power or intensity value for each of the plurality of wavelengths. The method further comprises determining a wavelength calibration error value for the wavelength feature by comparing the spectrum with a segment of a predetermined reference spectrum associated with the flash lamp, wherein the segment of the predetermined reference spectrum includes one or more wavelengths associated with the self-absorption feature; and calibrating the spectrophotometer based on the wavelength calibration error value.

The invention discloses a design method of a wavenumber linearity dispersion optical system and an imaging spectrometer, including: building an optical system including a grating, a prism and an objective lens that are sequentially arranged, the grating adjoins the prism; defining a linearity evaluation coefficient RMS; assigning a minimum value to the linearity evaluation coefficient RMS through adjustment to the vertex angle of the prism, when the linearity evaluation coefficient RMS is at minimum, the vertex angle of the prism being α.sub.1; acquiring compensations for distortion and longitudinal chromatic aberration of the objective lens based on the interval between equal-difference wavenumbers on the image plane when the vertex angle of the prism is α.sub.1; and optimizing the objective lens based on the compensations for distortion and longitudinal chromatic aberration of the objective lens to obtain an optimized optical system. Higher wavenumber linearity can be achieved through objective-lens-aberration compensated wavenumber linearity.

A measurement system comprising one or more semiconductor diodes configured to penetrate tissue comprising skin. The detection system comprising a camera, which may also include a direct or indirect time-of-flight sensor. The detection system synchronized to the pulsing of the semiconductor diodes, and the camera further coupled to a processor. The detection system non-invasively measuring blood within the skin, measuring hemoglobin absorption between 700 to 1300 nm, and the processor deriving physiological parameters and comparing properties between different spatial locations and variation over time. The semiconductor diodes may comprise vertical cavity surface emitting lasers, and the detection system may comprise single photon avalanche photodiodes. The measurement system may be used to observe eye parameters and differential blood flow. The system may be used with photo-bio-modulation therapy, or it may be used in advanced driver monitoring systems for multiple functions including head pose, eye tracking, facial authentication, and smart restraint control systems.

An active remote sensing system is provided with an array of laser diodes that generate light directed to an object having one or more optical wavelengths that include at least one near-infrared wavelength between 700 nanometers and 2500 nanometers. One of the laser diodes pulses with pulse duration of approximately 0.5 to 2 nanoseconds at repetition rate between one kilohertz and about 100 megahertz. A beam splitter receives the laser light, separates the light into a plurality of spatially separated lights and directs the lights to the object. A detection system includes a photodiode array synchronized to the array of laser diodes and performs a time-of-flight measurement by measuring a temporal distribution of photons received from the object. The time-of-flight measurement is combined with images from a camera system, and the remote sensing system is configured to be coupled to a wearable device, a smart phone or a tablet.

A system for a high resolution optical spectrum analyzer (OSA) using an efficient multi-pass configuration is disclosed. The system may include an entrance slit to allow inward passage of an optical beam. The system may also include a grating element to diffract the optical beam. The system may further include a retroreflective element to retroreflect the optical beam. The system may also include a mirror to reflect the optical beam. The system may include an exit slit, which in some examples may be adjacent to the entrance slit. The exit slit may allow outward passage of the optical beam for a high resolution optical measurement.

An optical system measures one or more physiological parameters with a wearable device that includes a light emitting diode (LED) source including a driver and a plurality of semiconductor sources that generate an output optical light. One or more lenses deliver a lens output light to tissue of a user. A detection system receives at least a portion of the lens output light reflected from the tissue and generates an output signal having a signal-to-noise ratio. The detection system comprises a plurality of spatially separated detectors and an analog to digital converter. The detection system increases the signal-to-noised ratio by comparing a first signal with the LEDs off to a second signal with the LEDs on. An imaging system including a Bragg reflector is pulsed and has a near infrared wavelength. A beam splitter splits the light into a sample arm and a reference arm to measure time-of-flight.

A monochromator apparatus for an optical spectrum analyzer may include a diffraction grating, a rotatable oblique prism reflector element with a non-right-angle apex angle, and a mirror. An input optical beam received from an input component may be diffracted by the grating element and reflected by a reflector element, where the reflector element may include a rotatable oblique prism with an apex angle that is different from a right angle. A mirror may reflect the reflected diffracted optical beam back to the reflector element and the grating element. An output optical beam from the grating element may be provided via an output element to a detection element for high resolution optical measurement. The oblique prism reflector element may reduce or eliminate a Littrow ghost effect or secondary ghost effects caused by the grating element.

A detector system for Fourier spectroscopy such as a spectral domain optical coherence tomography instrument includes a diffractive optic for diffracting the interfering light into angularly dispersed wavenumbers, a prism for reduces a nonlinear angular dispersion among the wavenumbers, and a focusing optic for converting the angularly dispersed wavenumbers from the prism into spatially distributed wavenumbers along a detector having an array of pixels. A field lens between the focusing optic and the detector has a freeform surface for more evenly distributing the wavenumbers along the array of pixels.

A light splitting device includes an optical waveguide body and a dispersion grating. The optical waveguide body is configured to transmit incident light to the dispersion grating, the dispersion grating is configured to disperse the incident light transmitted by the optical waveguide body into a plurality of spectral lines, and the optical waveguide body is further configured to change propagation directions of the plurality of spectral lines and to emit the plurality of spectral lines.

Spectrometers include an optical assembly with optical elements arranged to receive light from a light source and direct the light along a light path to a multi-element detector, dispersing light of different wavelengths to different spatial locations on the multi-element detector. The optical assembly includes: (i) a collimator arranged in the light path to receive the light from the light source, the collimator including a mirror having a freeform surface; (2) a dispersive sub-assembly including an echelle grating, the dispersive sub-assembly being arranged in the light path to receive light from the collimator; and (3) a Schmidt telescope arranged in the light path to receive light from the dispersive sub-assembly and focus the light to a field, the multi-element detector being arranged at the field.