A smoke detector includes a laser light source to provide incident light. The smoke detector also includes a Fabry-Perot etalon to transmit some incoming light, which is produced from the incident light, as transmitted light. Smoke particles in a cavity of the Fabry-Perot etalon affect an intensity of one or more wavelengths of the transmitted light.

It is proposed to use self-mixing interferometry for determining an absorption. The monitoring device for use in lateral flow testing for detecting presence or amount of an analyte in a liquid includes a housing, the housing including a carrier holder for holding a carrier for transport of the liquid; at least a first light source which is a resonant-cavity light source having a cavity; and an evaluation unit, operationally connected to at least the first light source for detecting a measurement signal. The first light source is structured and arranged to illuminate with light a test range in a test area of a carrier held in the carrier holder; and to couple back into the cavity of the first light source a portion of the light coming back from the test range.

An interferometric fluid sensing system is provided. The system comprises: a laser; a plurality of first fibre portions arranged to receive laser light from the laser, wherein each of the first fibre portions comprises a void and an opening to allow fluid from the environment around the corresponding first fibre portion to enter the void, wherein the first fibre portions are configured such that the laser light received by each first fibre portion passes through the corresponding void; a second fibre portion configured to provide a reference arm for the interferometric fluid sensing system; and a detector arranged to receive light from the first and second fibre portions, wherein the system is configured such that the laser light that passes through the void of each first fibre portion is caused to interfere with the light passing through the second fibre portion at or before reaching the detector, wherein each of the first fibre portions is arranged such that that light passing through the void of each first fibre portion travels from the laser to the detector over a different path length from the light passing through the voids of the other first fibre portions, wherein the system is configured such that the wavelength of light provided by the laser varies with time according to a modulated function, the modulated function comprising a first function, which varies through a range of wavelengths, modulated by a second, cyclical carrier function. An interferometric fluid detection method is also provided.

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.

A detector system for spatially resolved detection of a gas substance in an area is described. The detector system includes a detector comprising an image sensor; a band filter arranged in an optical beam path before the detector for transferring a beam with a wavelength spectrum including an absorption wavelength corresponding to the gas substance, a telescope, a polarizing beam splitter, and an interferometric stage including a retarder for creating an optical path difference for measuring absorption dips due to the presence of the gas substance. The retarder includes multiple birefringent media arranged with the optical axes relative to each other so that at least one increases an optical path difference and at least one decreases an optical path difference between the polarized beam components, and the thicknesses of the birefringent media are tuned to minimize a focal shift between the polarized beam components.

A smoke detector includes a laser light source to provide incident light. The smoke detector also includes a Fabry-Perot etalon to transmit some incoming light, which is produced from the incident light, as transmitted light. Smoke particles in a cavity of the Fabry-Perot etalon affect an intensity of one or more wavelengths of the transmitted light.

A system for sensing analyte in at least partly translucent material, including one or more radiation sources configured for successively providing radiation at a first and a second wavelength, respectively, two or more waveguides for simultaneously transmitting the radiation at each wavelength provided by the radiation source, a first waveguide being a reference waveguide and a second being a sensing waveguide; and measuring means for measuring a phase difference between the radiation waves from the reference waveguide and the measuring waveguide, resp. The present method can be used for measuring contaminants such as Fe, Sn, and/or Pb in oil related products, such as carburant or lubricant.

A gain switched dual comb spectroscopy device for spectroscopically detecting a sample substance, comprising a first slave laser light source configured to generate a first frequency comb having a first comb free spectral range, and a second slave laser light source configured to generate a second frequency comb having a second comb free spectral range which is different from the first comb free spectral range. A master laser light source is configured to inject seed light in to both slave laser light sources therewith to injection lock the generation of both the first and the second frequency combs. A photodetector part is arranged to combine the first and the second frequency combs and to detect a beat signal the spectrum of which comprises a third frequency comb including beat tones produced by interference between the combined first and second frequency combs.

The present disclosure concerns a sensor for the acquisition of an optical signal modulated at an acoustic frequency, including a plurality of pixels, each including: a photodiode; an integration circuit configured to, at each period of the modulated optical signal, integrate a photocurrent delivered by the photodiode successively into K capacitors, K being an integer greater than or equal to 2; and a phase detection circuit configured to detect an order in the crossing of a predetermined voltage threshold by the K capacitors and to generate, according to the detected order, a signal representative of the phase of the modulated optical signal.

A method for studying cell viability and protein aggregation involves establishing a Fabry Perot etalon signal within an optical spectroscopic feature, e.g., in the near infrared region. Protein aggregation and cell viability can be reflected by changes observed in the magnitude of the Fourier Transform peaks observed in the frequency or space domain associated with the contrast of the etalon. In short, the presence of viable cells and protein aggregates can degrade the etalon contrast of an etalon window. In some cases, the concentration of cells and monomeric protein can be measured as well.