An imaging system comprising circuitry configured to obtain (S2) image data of a scene that is illuminated with patterned light (PL), determine (S5, S6) bright regions and dark regions based on the image data, and relate image information related to the bright regions to image information related to the dark regions in order to determine characteristics of atmospheric aerosol particles (AP).

A method and system for imaging thermodynamic phase of clouds includes obtaining a spatially-resolved polarimetric image of a region of the sky containing a cloud using a multipixel image sensor having multiple channels corresponding to different wavelength bands, determining a value of the Stokes S.sub.1 polarization parameter of incident light on each pixel corresponding to a portion of the image containing the cloud for multiple channels corresponding to different wavelength bands, and determining the thermodynamic phase of the cloud within the image based on the values of the Stokes S.sub.1 polarization parameter. The Stokes S.sub.1 polarization parameter values determined for a first channel corresponding to a first wavelength band is used to determine a liquid thermodynamic phase, and the Stokes S.sub.1 polarization parameter values determined for a second channel corresponding to a second, shorter wavelength band is used to determine an ice thermodynamic phase.

A method and system for optical vortex transmissometry. The method uses optical orbital angular momentum (OAM) and optical vortices to discriminate coherent non-scattered light from incoherent scattered light. The system includes a laser which transmits a Gaussian laser beam through a medium. An OAM generating device is placed before a photodetector receiver. Coherent, non-scattered light passing through the OAM generating device forms an optical vortex, used to discriminate against the unwanted scattered signal that does not form a vortex. Alternatively, the system includes a transmitter, which generates one or more OAM modes, which are transmitted through a turbid medium. At the receiver, an OAM detection device analyzes the OAM mode spectrum of the received light. Coherent non-scattered light retains the OAM encoded at the transmitter, while scattered light does not. The attenuation of the channel is determined by comparison of the received OAM mode spectrum relative to the transmitted OAM mode spectrum.

The present disclosure provides to a novel two-target method for measuring the concentration of dust clouds, and an apparatus system that uses the novel two-target method. Cornstarch, corn dust, and saw dust are tested with the apparatus system with the method. This method used the light extinction coefficient of a dust cloud between two targets using a digital camera. This extinction coefficient is linearly related to the concentration of the dust, and the mass extinction coefficient is the key value for this measurement method. The mass extinction efficiency (K) depend greatly on the physical and chemical properties of the dust particles.

An optical sensor for an aircraft includes two detectors, a light source, and a controller. The detectors are oriented along detector paths and have tilt angles and fields of view. The detectors are configured to detect light reflected from an illumination volume and to generate detector signals that correspond to intensities of detected light. The tilt angles are equal such that each detector is oriented in an opposite direction within a plane containing a light source path and the detector paths. The light source is oriented along the light source path and is configured to illuminate the illumination volume which overlaps with the fields of view within a predetermined distance range. The controller is configured to receive the detector signals, detect whether a cloud is present based upon the detector signals, determine a cloud phase, and calculate a density of the detected cloud.

A simulator and test method of polarization transmission in sea fog belong to the technical field of polarization transmission characteristics. The simulator comprises an emitting device, a receiving device, a main box body, an automatic light alignment system, a water fog layer calibration system, a salt fog layer calibration system, and an aerosol layer calibration system. In accordance with the present disclosure, the automatic alignment of polarized light and a relatively stable sea fog environment are simulated in an indoor environment, the accuracy of indoor simulation is improved, the conformity between measured data and a theoretical simulation result is superior to 80%, and a reliable technical support is provided for the sea surface detection.

A visibility meter, a street light device and an operation method thereof are provided. The visibility measurement method includes: transmitting a visible laser through an optical transmitter; receiving the visible laser through an optical sensor to generate a sensed result; and calculating a visibility according to the sensed result.

A filter for a micropulse differential absorption LIDAR is provided. The filter comprises an etalon including a free spectral range substantially the same as a difference between a first laser wavelength and a second laser wavelength, the etalon further including a finesse providing substantial background noise suppression and substantially constant transmission of the first laser wavelength and the second laser wavelength over a predetermined range of wavelengths, and a first filter having a first filter bandpass selected to include the first laser wavelength and the second laser wavelength.

A rain and fog testing apparatus, comprising a fluid channel that runs between a first fluid shutoff coupler and a second fluid shutoff coupler and has at least one dispersion head fluidly coupled to the fluid channel. A liquid pump can be fluidly coupled to the fluid channel at an output end. A liquid heater may also be fluidly coupled to the system along with a controller that provides electrical control of the first fluid shutoff coupler, the second fluid shutoff coupler, the dispersion head, the liquid pump, and the heater. Further, the second fluid shutoff coupler is capable of fluidly coupling a first fluid channel to a plurality of fluid channels and the controller can adjust the orientation of the first fluid shutoff coupler, the second fluid shutoff coupler, the dispersion head, the liquid pump, and the liquid heater to create a simulation of a plurality of rain or fog events.

A method is provided for tracking-based visibility range estimation for a vehicle, the method including a step of tracking an object detected in a first image at a first point in time and in a second image at a second point in time, a step of ascertaining a first object luminance of the object and a first distance to the object at the first point in time and also ascertaining a second object luminance of the object and a second distance to the object at the second point in time, and also a step of determining an atmospheric extinction coefficient using the first object luminance, the second object luminance, the first distance, and the second distance, the atmospheric extinction coefficient being in direct correlation to visibility range.