In various implementations, a sample cell for optical analysis can include a housing configured to confine a sample to be analyzed. The cell can include at least one planar reflector and at least one concave reflector. The at least one planar reflector can be disposed in the housing to receive light from a light source. The at least one concave reflector can be disposed in the housing with respect to the at least one planar reflector to receive light reflected from the at least one planar reflector and to reflect at least of portion of the light back to the at least one planar reflector. The at least one planar reflector can be configured to reflect at least a portion of the light away from said at least one planar reflector to be analyzed.

An embodiment of a gas analyzer is described that comprises a light source configured to produce a substantially collimated first beam with a diverging angle of less than about 15 degrees; a gas cell comprising an inlet configured to introduce a gas into the gas cell, an outlet configured to remove the gas from the gas cell, and a plurality of mirrors configured to reflect the substantially collimated first beam within the gas cell; and a detector configured to generate a signal in response to the substantially collimated first beam.

A multipass cell (300) comprising: a first reflector arrangement (305A, 305B); and a second reflector arrangement (307), the first (305A, 305B) and second (307) reflector arrangements defining an optical cavity (315) therebetween and the cell; wherein the first reflector arrangement (305A, 305B) is configured such that light incident on the first reflector arrangement (305A, 305B) is at least partially retroreflected towards the second reflector arrangement (307), wherein the second reflector (307) arrangement comprises a concave surface that is reflective, wherein at least one of the first (305A, 305B) and second (307) reflector arrangements comprises an aperture (306) for allowing light to enter and/or exit the optical cavity (315).

A stable and highly accurate gas detections apparatus is provided. A gas detection apparatus 1 includes a light emitting element 3 provided on a main surface 20 of the substrate 2 for emitting light from a light emitting surface 31; a light receiving element 4 provided on the main surface 20 of the substrate 2 for receiving the light on a light receiving surface 41; and a light guide member 5 for guiding the light emitted by the light emitting element 3 to the light receiving element 4. In plan view of the main surface of the substrate, the light emitting surface 31 and the light receiving surface 41 are shaped to have corners, and side of the light emitting surface 31 after being subjected to a magnification or reduction and a translation do not overlap sides of the light receiving surface 41.

A gas sensor (1) is described comprising a light source (2), and a detector (4), a first reflector (7), which is concave and arranged to reflect and concentrate light emitted from the light source (2) to a first light spot (31), and an interference filter (5). The gas sensor comprises a second reflector (8), a third reflector (9), which is concave, and a reflector base (37) with a dome shaped surface (17) with the first and third reflectors facing the light source (2) and the detector (4). During operation of the gas sensor (1), the detector (4) is illuminated by light from the light source (2), which in an optical path from the light source (2) has been reflected at least once in each one of the first reflector (7), the second reflector (8), and the third reflector (9). The gas sensor (1) is configured for detection of a first wavelength portion of the light.

Systems, devices, and methods including a modified Herriot cell comprising: a laser configured to generate a single beam; a partially transmissive region (PTR) disposed in at least one of: a first mirror and a second mirror, where a first portion of the single beam is received through the PTR, and wherein a second portion of the single beam is reflected by the PTR; a first detector disposed proximate the PTR, wherein the first detector receives the first portion of the beam, and where the first portion of the beam has traveled a first path length from the laser to the first detector; and a second detector disposed proximate the exit hole, where the second detector receives the second portion of the beam, and wherein the second portion of the beam has traveled a second path length from the laser to the second detector.

The present disclosure relates to a device for measuring a first analyte concentration and a second analyte concentration in a measuring medium, the device including: a sample cell; a first light source unit; a first detector unit; a functional element; a second light source unit; a second detector unit; and a control unit adapted to analyze a detected first light for determining a first value representing the concentration of the first analyte in the measuring medium and adapted to analyze a detected third light for determining a second value representing the concentration of the second analyte in the measuring medium. A method of using the device is also disclosed.

Provided is a water examination device including: a main body; a fluid accommodation unit formed in the main body; a wave source for irradiating waves toward the fluid accommodation unit; a detector for detecting a laser speckle at every set time period that is set in advance, the laser speckle being generated due to multiple scattering of the waves in the fluid; a controller for estimating existence of impurities in the fluid in real-time by using the detected laser speckle; and a calibration unit for controlling the wave source or the detector such that an intensity of light irradiated from the wave source and measured by the detector is within a certain range set in advance.

A laser-based detection and analysis system for detecting plural members of volatile organic compounds includes a measuring unit configured to simultaneously measure a spectrum of the plural members of the volatile organic compounds located in a measuring chamber, with a laser beam having a wavelength of about 3.3 μm, and a data processing unit including a deep neural network, DNN, configured to process the spectrum measured by the measuring unit and to output an individual concentration of each of the plural members of the volatile organic compounds. The DNN is configured to update a weight W.sub.k for each member of the plural members by using hidden layers having plural nodes, each node having an activation function and an optimizer.

In one illustrative configuration, an air quality monitoring system may enable wide-scale deployment of multiple air quality monitors with high-confidence and actionable data is provided. Further, the air quality monitoring system may enable identifying a target emission from a plurality of potential sources at a site based on simulating plume models. The simulation of plume models may take into consideration various simulation parameters including wind speed and direction. Further, methods of determining a plume flux of a plume of emissions at a site, and methods of transmitting data from an air quality monitor are disclosed.