A multi-point detection system includes one or more light sources, one or more light sensors, and a controller. The light sources are configured to emit an array of collimated light beams, and the light sensors define an array of lines of view. Each of the lines of view intersect different ones of the collimated light beams at respective detection nodes. The light sensors are operable to emit sensor signals responsive to received scattered light from interaction of the collimated light beams with an analyte at the detection nodes. The controller is connected to receive the sensor signals and configured to determine from the scattered light whether the analyte contains a contaminant.

Methods and apparatus for detecting biological agents suspended in air in real time. A method includes emitting towards an air sample a beam of monochromatic polarized light whose wavelength corresponds to an absorption maximum of a biological molecule. The method further includes receiving, at different scattering angles, the scattered light beam after passing through the sample and determining that there are particles in the sample that contain the biological molecules of interest if the intensity of the scattered light has a substantially higher peak than the rest of the scattered light. The amount of the biological molecules is then estimated according to the amplitude of the peak. The size of the particles containing the biological molecules is also estimated as a function of the scattering angle where the peak was detected.

Systems and methods of performing a stress measurement of a chemically strengthened glass using a light-scattering polarimetry system include adjusting the intensity of a light beam from a light source in an illumination system using a rotatable half-wave plate and a first polarizer operably disposed between the light source and a rotating light diffuser that has a rotation time t.sub.R. The first polarizer is aligned with a second polarizer in a downstream optical compensator to have matching polarization directions by rotating the rotatable half-wave plate to a position where the exposure time t.sub.E falls within an exposure range t.sub.R≤t.sub.E. The method also includes performing an exposure using the exposure time t.sub.E to obtain the stress measurement. One or both of the half-wave plate and first polarizer can be tilted to avoid deleterious back-reflected light from entering the light source.

Provided is an apparatus for detecting smoke based on polarization. The apparatus includes a chamber into which smoke is introduced, a detection unit comprising a light-emitting unit configured to emit light beams having a plurality of different wavelengths into a space in the chamber, and a light-receiving unit configured to receive scattered light from a plurality of light sources, a control unit configured to control an operation of the detection unit, and a fire determination unit configured to distinguish between fire smoke and non-fire analogous smoke by detecting and analyzing a light-receiving signal received by the light-receiving unit, in which horizontal polarization and vertical polarization are applied to the plurality of light sources of the light-emitting unit and the light-receiving unit.

The invention relates to a system (1) for observing objects, including: a light source (3), a holder (12) able to receive a translucent or opaque substrate, a detector (7) able to collect the backscattered light from the interaction between the light emitted by light source (3) and the objects, a polarization splitter (9), and a quarter-wave plate (10), the splitter (9) and the quarter-wave plate (10) being arranged so that the splitter (9) directs the light emitted by the light source (3) toward the solid substrate and directs the backscattered light from the interaction between the light emitted by the light source (3) and the objects toward the detector (7).

Additive manufacturing, such as laser sintering or melting of additive layers, can produce parts rapidly at small volume and in a factory setting. To ensure the additive manufactured parts are of high quality, a real-time non-destructive evaluation (NDE) technique is required to detect defects while they are being manufactured. The present invention describes an in-situ (real-time) inspection unit that can be added to an existing additive manufacturing (AM) tool, such as an FDM (fused deposition modeling) machine, or a direct metal laser sintering (DMLS) machine, providing real-time information about the part quality, and detecting flaws as they occur. The information provided by this unit is used to a) qualify the part as it is being made, and b) to provide feedback to the AM tool for correction, or to stop the process if the part will not meet the quality, thus saving time, energy and reduce material loss.

A detection device includes: a light source that emits, toward an object, light of a first wavelength band, and light of a second wavelength band that is less readily absorbed by water than the light of the first wavelength band; a polarization splitter that splits at least one of S-polarized light and P-polarized light from light that has been reflected or scattered at the object; a photoreceptor that receives light reflected or scattered at the object via the polarization splitter; and a control unit that determines a state of the object from information based on light received by the photoreceptor. The light emitted by the light source is random polarized light where the ratio of P-polarized light and S-polarized light is generally uniform.

Laser speckle microrheology is used to determine a mechanical property of a biological tissue, namely, an elastic modulus. Speckle frames may be acquired by illuminating a coherent light and capturing back-scattered rays in parallel and cross-polarized states with respect to illumination. The speckle frames may be analyzed temporally to obtain diffuse reflectance profiles (DRPs) for the parallel-polarized and cross-polarized states. A scattering characteristic of particles in the biological tissue may be determined based on the DRPs, and a displacement characteristic may be determined based at least in part on a speckle intensity autocorrelation function and the scattering characteristic. A size characteristic of scattering particles may be determined based on the DRP for the parallel polarization state. The mechanical property may be calculated using the displacement and size characteristics.

Apparatus and associated methods relate to determining metrics of water particles in clouds by directing light pulses at a cloud and measuring a peak, a post-peak value and a high-frequency fluctuation of light signals reflected from the cloud. The light pulses include: a first pulse having circularly polarized light of a first wavelength; and a second pulse of a second wavelength. The reflected light signals include: a first reflected light signal having left-hand circular polarization of the first wavelength; a second reflected light signal having right-hand circular polarization of the first wavelength; and a third reflected light signal of the second wavelength. An extinction coefficient and a backscatter coefficient are determined based on the measured peak and post-peak slopes of the first and second reflected light signals. The measured high-frequency fluctuations of the three reflected light signals can be used to calculate cloud particle sizes.

Provided herein is an apparatus, including an optical characterization device; a photon detector array configured to sequentially receive a first set of photons scattered from surface features of an article and a second set of photons scattered from surface features of the article and subsequently processed by the optical characterization device; and a chemical characterization means for chemically characterizing the surface features of the article, wherein the chemical characterization means is configured for processing the first set of photons received by the photon detector array and the second set of photons received by the photon detector array.