An apparatus for carrying out Raman spectroscopy on a sample includes a light source for providing a beam of excitation radiation, and an optical system including a spectrograph. The spectrograph includes a grating that divides a beam of scattered light into a spectrum of spatially separated wavelength components and to direct a portion of the spectrum to a detector. The spectrograph includes: 1) a first lens system for focusing the portion of the spectrum onto the detector and 2) a second lens system-configured to provide a focal plane with focal point in the optical path for focusing the beam of excitation radiation and/or the beam of scattered radiation at the focal point. The apparatus including a reference sample arranged in the focal plane, in particular at the focal point, for obtaining a reference spectrum from the reference sample.

A measuring apparatus for measuring a spectrum of a gaseous sample includes a tunable laser light source to provide an illuminating light beam, a sample cell with an inner surface to provide scrambled light that is transmitted through the gaseous sample, a detector to detect intensity of transmitted scrambled light and a pressure control system to maintain an absolute pressure of the gaseous sample smaller than 50 kPa inside the sample cell to reduce spectral widths of spectral features of the gaseous sample. The measuring apparatus measures spectral transmittance values of the sample by modulating the spectral position of the illuminating light, and detecting the intensity of the transmitted light at different spectral positions. The divergence of the illuminating light beam in a transverse direction is greater than 30° to cause multiple consecutive reflections of the scrambled light from the inner surface.

A method for measuring multiple parameters of mixed gases based on broadband infrared light source is provided, including: filtering a broadband infrared laser, and forming a laser beam including three narrow-linewidth wavelengths; dividing the laser beam into a first sub-laser beam and a second sub-laser beam; focusing and transmitting the first sub-laser beam to a gas sample cell; focusing and transmitting the first sub-laser beam to a first reflector; reflecting and transmitting the first sub-laser beam; reflecting and transmitting the second sub-laser beam to the second beam splitter; combing the first sub-laser beam transmitted by the second beam splitter and the second sub-laser beam reflected by the second beam splitter, measuring the multiple parameters; combining and transmitting the second sub-laser beam transmitted by the second beam splitter and the first sub-laser beam reflected by the second beam splitter to a spectrometer for measuring concentrations the mixed gases.

Provided herein is an apparatus for assessing a color characteristic of a gemstone. The apparatus comprises an optically opaque platform for supporting a sample gemstone to be assessed, a daylight-approximating light source to provide uniform illumination to the gemstone, an image capturing component, and a telecentric lens positioned to provide an image of the illuminated gemstone to the image capturing component. Also provided are methods of color analysis based on images collected using such an apparatus.

The invention aims to provide an inspection device that can sensitively detect a defect even if intensity of scattered light reflected from an inspection object greatly varies depending on portions of the inspection object. An inspection device according to the invention uses a history of detection signals to predict whether a next detection signal level exceeds a threshold. When the detection signal level is predicted to exceed the threshold, operation of the device is beforehand changed such that the detection signal level does not exceed the threshold.

An optical density testing system includes a light source, a first light splitting device used to divide the light into at least two light paths, at least two second light splitting devices used for receiving the at least two paths of light from the first light splitting device, first light-passing holes provided corresponding to each of the at least two second light splitting devices, a first filter device detachably arranged at each of the first light-passing holes, a first diaphragm detachably installed on each of the first filter devices, and a light receiving device. The second light splitting device is used to transmit the light onto a product to be tested through the first filter device and the first diaphragm. The light receiving device is used to receive transmitted light formed after the light passes through the product to be tested.

Methods and systems for gas detection are provided. Aspects include determining a target gas for detection in a sampling chamber, determining one or more target characteristics of light based on the target gas, operating a light source to transmit the light through a sampling chamber to an optical element, operating an active optical element to modulate the light based on the one or more target characteristics of the light, operating a filter to receive the light from the optical element and separate the light in to a first light portion and a second light portion, operating the photodetector to receive the first light portion from the filter, and analyzing the first light portion to determine a presence of the target gas in the sampling chamber.

A method of determining overlay (“OVL”) in a pattern in a semiconductor wafer manufacturing process comprises capturing images from a cell in a metrology target formed in at least two different layers in the wafer with parts of the target offset in opposing directions with respect to corresponding parts in a different layer. The images may be captured using radiation of multiple different wavelengths, each image including +1 and −1 diffraction patterns. A first and second differential signal may be determined for respective pixels in each image by subtracting opposing pixels from the +1 and −1 diffraction orders for each of the multiple wavelengths. An OVL for the respective pixels may be determined based on analyzing the differential signals from multiple wavelengths simultaneously. Then an OVL for the pattern may be determined as a weighted average of the OVL of the respective pixels.

The invention relates to a system (15) for observing a plate (10) including wells (20), including, for each well (20): a source (40) comprising a light-emitting diode (60) capable of producing a light ray, a pinhole (70), and a light integrator (65), an optical sensor (185) able to collect the optical signal from the well (20), the system (15) being such that: a ratio between the length and the average transverse dimension (Dt) of each light integrator (65) is greater than or equal to 2.2, or at least one optical axis is off-centered relative to the propagation line, the ratio between the length and the average transverse dimension of the integrator being greater than or equal to 1.5.

Embodiments relate generally to electromagnetic radiation detector devices, systems, and methods using a planar Golay cell. A method for gas detection may comprise providing a gas sealed in a cavity of a gas detector; directing radiative power from a light source through one or more target gases and through a cell body of the gas detector toward the cavity and a wavelength selective absorber of the gas detector, wherein the one or more target gases are located between the light source and the cavity; setting wavelength sensitivity with the wavelength selective absorber, wherein the wavelength sensitivity is irrespective of an angle of incidence (?); absorbing the radiative power by the wavelength selective absorber and by the one or more target gases; detecting, by a pressure sensing element, a pressure change caused by the absorbing of the radiative power; and determining the one or more target gases based on the detected pressure change.