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.

An optical environment oscillation detection system and an optical measurement method using the same are provided. This system includes a laser light source, a polarizer, a liquid crystal (LC) element, an analyzer, and an optical sensor arranged in sequence. A polarization axis of the polarizer and that of the analyzer are respectively parallel to a first and a second axis direction being perpendicular to each other. When there is no environmental disturbance, the alignment of LC cells in the LC element has an original pretilt angle, and the optical sensor senses a first scattered light intensity of the laser beam outputted from the analyzer. When there is environmental disturbance, the alignment of the LC cells has a changed pretilt angle in relative to the original pretilt angle, and the optical sensor senses a second scattered light intensity of the laser beam outputted from the analyzer.

An optical turbulence measurement system may include a camera assembly, a first optics assembly, a second optics assembly, and processing circuitry. The first optics assembly and the second optics assembly may be configured to magnify and direct a portion of a source beam received by a respective aperture to the camera assembly to be received as a two portions of a received beam. The processing circuitry may be configured to receive, from the camera assembly, a data representation of a first received beam from the first optics assembly and a second received beam from the second optics assembly, determine a focal spot displacement variance based on motion of a first focal spot corresponding to the first received beam relative to a second focal spot corresponding to the second received beam, and measure optical turbulence along a path of the source beam based on the focal spot displacement variance.

A transmissometer and method for determining a transmissivity of an atmosphere within a chamber. A chamber contains the atmosphere. A light source generates a test beam and a light detector detects the test beam. A periscope is movable between a first position which allows the test beam to pass through the atmosphere in the chamber and into the light detector and a second position in which the test beam is deflected to pass into the light detector without passing through the atmosphere in the chamber. A processor determines the transmissivity of the atmosphere from a transmissivity measurement for the test beam obtained by the light detector when the periscope is in the first position and a transfer standard obtained at the light detector when the periscope is in the second position.

A method is provided for detecting a property of a gas comprising: emitting a light, comprising a plurality of wavelengths covering a plurality of absorption lines of the gas, along a first axis, the light being scattered by particles of the gas resulting in a scattered light, generating a sensor image using a detection arrangement configured to receive the scattered light and comprising: an optical arrangement having an optical plane and being configured to direct the scattered light on to a light sensor, the light sensor having at least one pixel columns, wherein the pixel columns are aligned to an image plane and configured to output a sensor image, wherein the first axis, the optical plane, and the image plane intersect such that a Scheimpflug condition is achieved, determining, from the sensor image, properties of the gas at a plurality of positions along the first axis.

An optical turbulence measurement system may include a camera assembly, a first optics assembly, a second optics assembly, and processing circuitry. The first optics assembly and the second optics assembly may be configured to magnify and direct a portion of a source beam received by a respective aperture to the camera assembly to be received as a two portions of a received beam. The processing circuitry may be configured to receive, from the camera assembly, a data representation of a first received beam from the first optics assembly and a second received beam from the second optics assembly, determine a focal spot displacement variance based on motion of a first focal spot corresponding to the first received beam relative to a second focal spot corresponding to the second received beam, and measure optical turbulence along a path of the source beam based on the focal spot displacement variance.

A method for capturing at least particle compositions (21) in a monitoring region (14) that exhibit a temporally dynamic behaviour with an optical detection apparatus (12), and an optical detection apparatus (12) are described. In the method, during at least one measurement, optical transmission signals (22) are transmitted into the monitoring region (14) and transmission signals (22) that are reflected at particle targets (28) of any particle compositions (21) present in the monitoring region (14) are received as particle reflection signals (30). The presence of dynamic particle compositions (21) is concluded from the particle reflection signals (30). At least two measurements are performed with a temporal distance. A particle target density or a variable characterizing the particle target density is ascertained for at least one partial volume (48) of the monitoring region (14) from the particle reflection signals (30) of each measurement. If the particle target density (52) or the variable characterizing it from the at least two measurements should differ by more than a prescribable or prescribed tolerance, it is concluded that the particle reflection signals (30) from the at least one partial volume are caused by the reflection of the transmission signals (22) at dynamic particle compositions (21).

A method is provided for detecting a property of a gas comprising: emitting a light, comprising a plurality of wavelengths covering a plurality of absorption lines of the gas, along a first axis, the light being scattered by particles of the gas resulting in a scattered light, generating a sensor image using a detection arrangement configured to receive the scattered light and comprising: an optical arrangement having an optical plane and being configured to direct the scattered light on to a light sensor, the light sensor having at least one pixel columns, wherein the pixel columns are aligned to an image plane and configured to output a sensor image, wherein the first axis, the optical plane, and the image plane intersect such that a Scheimpflug condition is achieved, determining, from the sensor image, properties of the gas at a plurality of positions along the first axis.

Methods and systems in accordance with the present invention provide a continuum measure of visibility from a single image without prior knowledge of the camera system or the cameras in the system. This may be, for example, a score on the weather visibility quality of the image, ranging from good to poor, or a numeric score representing the weather visibility quality of the terrain in the image. This may be done without prior knowledge of the camera system, the camera that took the image, or the environment. It is also done with the single image without using multiple images, or reference images. The system derives a real-time continuum measure of visibility from a single daytime image, with unknown camera quality, system configuration, and environmental conditions.

A system comprises an optical air data system that measures aerosol and molecular scattering of light, and an optical instrument that measures aerosol and/or molecular scattering of light. A processor receives data from the air data system and from the optical instrument. The processor performs one or more signal analysis and data fusion methods comprising: (a) determining aerosol and/or molecular concentration from the received data, modifying a data analysis algorithm to optimize any remaining unknown parameters, and outputting enhanced air data parameters; (b) determining aerosol concentration from the received data, dynamically optimizing hardware settings in the air data system to enhance a signal level and avoid system saturation, and outputting enhanced air data parameters; or (c) determining aerosol and/or molecular concentration from the received data, estimating a confidence level of an air data algorithm, verifying optical health of the air data system, and reporting the optical health to a user.