A particle detector formed by a body defining a chamber and housing a light source and a photodetector. A reflecting surface is formed by a first reflecting region and a second reflecting region that have a respective curved shape. The curved shapes are chosen from among portions of ellipsoidal, paraboloidal, and spherical surfaces. The first reflecting region faces the light source and the second reflecting region faces the photodetector. The first reflecting region has an own first focus, and the second reflecting region has an own first focus. The first focus of the first reflecting region is arranged in an active volume of the body, designed for detecting particles, and the photodetector is arranged on the first focus of the second reflecting region.

A bidirectional reflectance distribution function (BRDF) measurement system is provided that measures the BRDF across many photonic bands such as the UV, Vis, NIR, SWIR, MWIR, and LWIR (scale) simultaneously (speed) in an innovative measurement system. The measurement system includes an illuminating optical system, a detection system, and a calibration reference. The illuminating optical system directs illuminating light to an imaging location and the detection system detects returning light from the imaging location. The calibration reference including an optical metamaterial having a receiving surface. The calibration reference is placed at the imaging location and alters illuminating light incident on the receiving surface to produce returning light having known optical properties.

A particle detector formed by a body defining a chamber and housing a light source and a photodetector. A reflecting surface is formed by a first reflecting region and a second reflecting region that have a respective curved shape. The curved shapes are chosen from among portions of ellipsoidal, paraboloidal, and spherical surfaces. The first reflecting region faces the light source and the second reflecting region faces the photodetector. The first reflecting region has an own first focus, and the second reflecting region has an own first focus. The first focus of the first reflecting region is arranged in an active volume of the body, designed for detecting particles, and the photodetector is arranged on the first focus of the second reflecting region.

A sorting or classifying apparatus comprising an illumination device for providing illumination or foreground illumination, the illumination device comprising a reflector (61) which has a reflecting surface (63) providing a reflection envelope, a first light source (70) which is disposed in spaced relation in front of the reflecting surface (63) and provides light of a first spectral output to the reflecting surface (63) for reflection thereby and which first light source (70) comprises a plurality of light elements or incandescent lamps (72), wherein the light elements or lamps (72) are disposed on or near a focal axis (X) of the reflector (61), and a second light source (71) which is disposed in spaced relation in front of the reflecting surface (63) and provides light of a second spectral output, different to the first spectral output to the reflecting surface (63) for reflection thereby and which second light source (71) comprises a plurality of light elements or light-emitting diodes (LEDs) (75) arranged along at least one row (77a, b) which extends along the length of the reflecting surface (63) and is arranged in a direction substantially parallel to the focal axis (X) of the reflector (61), optionally the first light source (70) is a source of near infra-red (NIR) light and the second light source (71) is a source of visible-spectrum light.

A droplet sensor includes an optical cover having an ellipsoid surface that is a portion of a spheroid, a light source disposed at or in proximity to a first focal point of the ellipsoid surface, and a light detector disposed at or in proximity to a second focal point of the ellipsoid surface. The ellipsoid surface includes an effective detection area configured to reflect light emitted by the light source toward the light detector, and an amount of light reflected by the effective detection area changes in accordance with adhesion of droplets on the ellipsoid surface. The optical cover includes a space having a hemispherical surface, the space being centered at the second focal point. The hemispherical surface includes a transmission scattering surface on a region that receives the light reflected by the effective detection area.

A droplet sensor includes: an optical cover having an ellipsoid surface that is a portion of a spheroid; a light source disposed at or in proximity to a first focal point of the ellipsoid surface; and a light detector disposed at or in proximity to a second focal point of the ellipsoid surface, wherein the ellipsoid surface is an effective detection area configured to reflect light emitted from the light source toward the light detector, and an amount of light reflected by the effective detection area changes in accordance with adhesion of droplets on the ellipsoid surface, and wherein the optical cover has a curved surface that is tangentially connected to an outside of the effective detection area and having a curvature greater than a curvature of the ellipsoid surface.

Certain configurations are described herein of an optical spectrometer and instruments including an optical spectrometer. In some instances, the optical spectrometer is configured to spatially separate provided wavelengths of light to permit detection or imaging of each provided wavelength of light. Improved sensitivities and detection limits may be achieved using the optical spectrometers described herein.

System and apparatus for portable gas detection. Specifically, this disclosure describes apparatuses and systems for optical gas detection in a compact package. There is a need for a very compact, low-power, gas detection system for gases such as CO2, NOx, water vapor, methane etc. This disclosure provides an ultra-compact and highly efficient optical measurement system based on principals of optical absorption spectroscopy. It reduces the size of the instrument as well its power consumption by more than an order of magnitude making it possible to deploy it widely. There is an identified need for large number of distributed gas sensors to improve human health, environment, and save energy usage.

Certain configurations are described herein of an optical spectrometer and instruments including an optical spectrometer. In some instances, the optical spectrometer is configured to spatially separate provided wavelengths of light to permit detection or imaging of each provided wavelength of light. Improved sensitivities and detection limits may be achieved using the optical spectrometers described herein.

A sorting or classifying apparatus comprising an illumination device for providing illumination or foreground illumination, the illumination device comprising a reflector (61) which has a reflecting surface (63) providing a reflection envelope, a first light source (70) which is disposed in spaced relation in front of the reflecting surface (63) and provides light of a first spectral output to the reflecting surface (63) for reflection thereby and which first light source (70) comprises a plurality of light elements or incandescent lamps (72), wherein the light elements or lamps (72) are disposed on or near a focal axis (X) of the reflector (61), and a second light source (71) which is disposed in spaced relation in front of the reflecting surface (63) and provides light of a second spectral output, different to the first spectral output to the reflecting surface (63) for reflection thereby and which second light source (71) comprises a plurality of light elements or light-emitting diodes (LEDs) (75) arranged along at least one row (77a, b) which extends along the length of the reflecting surface (63) and is arranged in a direction substantially parallel to the focal axis (X) of the reflector (61), optionally the first light source (70) is a source of near infra-red (NIR) light and the second light source (71) is a source of visible-spectrum light.