A first optical system (10) according to the present disclosure includes a first lens (111) that guides light (LO) to a diffraction grating (3), a second lens (112) that collimates first diffracted light (L1) that was focused at a first focal point (f1), a pair of first mirrors (12, 13), a third lens (113) that focuses the first diffracted light (L1) at a second focal point (f2), and a fourth lens (114) that guides the first diffracted light (L1) that was focused by the third lens (113) to the diffraction grating (3). The first lens (111) and the fourth lens (114) have a substantially identical first focal length. The second lens (112) and the third lens (113) have a substantially identical second focal length. A first distance along an optical path from the first focal point (f1) to the second focal point (f2) is determined by a first predetermined condition.

A camera includes a first lens configured to focus incoming light onto a reflective slit assembly. The reflective slit assembly comprises an elongated strip of reflective material configured to reflect some but not all of the incoming light as return light. The first lens is configured to at least partially collimate the return light from the elongated strip of reflective material. A first mirror is configured to reflect the return light from the first lens. A second mirror is configured to reflect the return light from the first mirror. An optical element is configured to separate the return light from the first mirror as a function of wavelength. A second lens is configured to focus the return light from the optical element onto a first detector. The first detector is configured to measure intensities of the return light as a function of two dimensional position on the first detector.

A light detection device includes: a first support part disposed on a mounting surface of the wiring board; a Fabry-Perot interference filter disposed in a first support region of the first support part; and a temperature detector, wherein the temperature detector is disposed on the mounting surface such that at least a part of the temperature detector overlaps a part of the Fabry-Perot interference filter when seen in a first direction perpendicular to the mounting surface and such that at least a part of the temperature detector overlaps a part of the first support part when seen in a second direction in which the first support part and the light detector are aligned with each other, and wherein a first distance between the temperature detector and the first support part in the second direction is smaller than a first width of the first support region in the second direction.

A handheld spectrometer can be configured with a visible aiming beam to allow the user to determine the measured region of the object. When the visible aiming beam comprises the spectrometer measurement beam, the spectrometer measurement beam comprises sufficient energy for the user to see the measurement beam illuminating the object. When the visible aiming beam comprises a separate beam, the visible aiming beam comprises sufficient energy for the user to see a portion of the aiming beam reflected from the object. The visible aiming beam and measurement beam can be arranged to at least partially overlap on the sample, such that the user has an indication of the area of the sample being measured.

In a spectroscopic module, a light shielding member is disposed between a plurality of bandpass filters and a light detector. The light shielding member includes a plurality of wall portions. The plurality of wall portions are arranged along an X direction with a light passage opening interposed therebetween, each of a plurality of optical paths from the plurality of bandpass filters to a plurality of light receiving regions passing through the light passage opening. A first wall portion and a second wall portion adjacent to each other among the plurality of wall portions are in contact with the bandpass filter, the bandpass filter corresponding to the light passage opening between the first wall portion and the second wall portion. A width in a Y direction of the light passage opening is larger than a width in the Y direction of the bandpass filter.

A modular housing for a spectrometer, the housing comprising at least two modules, the housing further comprising: a sensor recess configured to receive a sensor, the sensor being configured for determining at least one light spectrum characteristic of light received after optical interaction of the light with a sample; an aperture configured for receiving and guiding the light received after the optical interaction along a reception path extending from an entrance of the aperture to the sensor recess; and at least two channels configured for guiding and emitting light out of the modular housing, such that the light, after the optical interaction with the sample, is received at the entrance of the aperture; wherein the at least two channels are arranged along intersecting or skew axes; and wherein at least two of the at least two modules comprise respective ones of the at least two channels.

Provided is a measurement device including a spectroscope, a movement mechanism configured to relatively move the spectroscope in one direction, and one or more processors configured to determine whether a measurement position measured by the spectroscope is moved into a color patch, in which the one or more processors cause the spectroscope to execute measurement processing for a plurality of wavelengths set in advance while relatively moving the spectroscope in the one direction, and when at least one of amounts of variation of measured values with respect to each of the plurality of wavelengths obtained in the measurement processing exceeds a first threshold value and then each of the amounts of variation of the measured values of the plurality of wavelengths falls below a second threshold value which is less than or equal to the first threshold value, determine that the measurement position is moved into the color patch.

A self-calibrating spectrometer that captures a sample spectrum image of a sample via a light dispersion device and a calibration spectrum image of a calibration light source having a known spectrum (e.g., in the same image frame using a bifurcated fiber optic cable). Spectral data is extracted from the sample spectrum image and wavelength calibrated by matching calibration spectral data extracted from the calibration spectrum image to the known spectrum of the calibration light source, mapping each pixel position of the calibration spectrum image to a wavelength of the known spectrum of the calibration light source, and mapping each pixel position of the sample spectral data to a wavelength based on the pixel position-to-wavelength mapping. In some embodiments, extracted features from the wavelength calibrated spectral data are used by classification module, trained on a dataset of features extracted from spectral data of known samples, to classify the sample.

A method of determining a peak intensity in an optical spectrum is described. The method includes producing a two-dimensional array of spectrum values by imaging the optical spectrum onto a detector array. An offset using an actual location and an expected location of a peak of an interpolated subarray is used to adjust an expected location of another peak that is within another two-dimensional subarray. Interpolated spectrum values are then used to produce a peak intensity value of the second peak.

An apparatus includes a base component and collimators housed within the base component. The collimators correspond to collection cylinders for sampling optical emission spectroscopy (OES) signals with respect to locations of a wafer in an etch chamber. The apparatus further includes a guide, operatively coupled to the plurality of collimators, to guide the sampling of the OES signals along paths for sampling the OES signals.