The invention relates to a device (1) and a method (20) for determining a spectrum (X) of scattered radiation (S). The invention further relates to a method (70) for calculating the spectrum (X) and a method for compressing unstructured data (60) of known distribution. To be able to determine the spectrum (X) as precisely as possible and to derive from this the characteristics of materials that scatter laser pulses (P), the invention proposes that at least one characteristic of the laser pulse (P) is determined and that a spectrum analyzer (5) is used for this. Frequencies (F) of laser pulses (P) and volumes (M) of backscattered radiation (S) are combined into frequency and volume values (F, M) to calculate the spectrum (X). The most frequent data values are deleted from the data to compress the data (60).

Solar spectral irradiance (SSI) measurements are important for solar collector/photovoltaic panel efficiency and solar energy resource assessment as well as being important for scientific meteorological/climate observations and material testing research. To date such measurements have exploited modified diffraction grating based scientific instruments which are bulky, expensive, and with low mechanical integrity for generalized deployment. A compact and cost-effective tool for accurately determining the global solar spectra as well as the global horizontal or tilted irradiances as part of on-site solar resource assessments and module performance characterization studies would be beneficial. An instrument with no moving parts for mechanical and environment stability in open field, non-controlled deployments could exploit software to resolve the global, direct and diffuse solar spectra from its measurements within the 280-4000 nm spectral range, in addition to major atmospheric processes, such as air mass, Rayleigh scattering, aerosol extinction, ozone and water vapor absorptions.

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.

A beam detector including a light source, a receiver, and a target, acting in cooperation to detect particles in a monitored area. The target reflects incident light, resulting in reflected light being returned to receiver. The receiver is capable of recording and reporting light intensity at a plurality of points across its field of view. In the preferred form the detector emits a first light beam in a first wavelength band; a second light beam in a second wavelength band; and a third light beam in a third wavelength band, wherein the first and second wavelengths bands are substantially equal and are different to the third wavelength band.

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 shared optics and telescope for transmitting a transmission beam and receiving a return signal is provided. The shared optics and telescope includes a pair of axicon lenses operable to shape the transmission beam into an annular beam having an outer diameter and an inner diameter, a secondary mirror operable to deflect the annular beam into a deflected annular transmission beam, and a primary mirror that includes an inner mirror portion and an outer mirror portion, the inner mirror portion operable to expand the deflected annular transmission beam, and the outer mirror portion operable to collect the return signal.

Solar spectral irradiance (SSI) measurements are important for solar collector/photovoltaic panel efficiency and solar energy resource assessment as well as being important for scientific meteorological/climate observations and material testing research. To date such measurements have exploited modified diffraction grating based scientific instruments which are bulky, expensive, and with low mechanical integrity for generalized deployment. A compact and cost-effective tool for accurately determining the global solar spectra as well as the global horizontal or tilted irradiances as part of on-site solar resource assessments and module performance characterization studies would be beneficial. An instrument with no moving parts for mechanical and environment stability in open field, non-controlled deployments could exploit software to resolve the global, direct and diffuse solar spectra from its measurements within the 280-4000 nm spectral range, in addition to major atmospheric processes, such as air mass, Rayleigh scattering, aerosol extinction, ozone and water vapour absorptions.

In order to properly detect an outbreak of smoke using a photographic image, this detection device is equipped with an extraction unit, a calculation unit, and a detection unit. By using an image analysis result of an input image, that is, a photographic image captured of a scene under surveillance, the extraction unit generates an image for which a noise component is removed from the input image. By using brightness information contained in the generated image, the calculation unit calculates an attenuation factor of reflected light from a captured object in the input image. The detection unit determines whether an outbreak of smoke is present in the scene under surveillance based on the attenuation factor.

The invention pertains to an aerosol detector system for spatially resolved detection of an aerosol distribution in an area, comprising: a wide field polarization preserving telescope having telecentric imaging optics for imaging the earth surface onto a detector; said detector receiving phase stepped images imaged by said telescope; and a controller coupled to the detector, arranged to provide a resulting image as a function of corresponding pixel values of the multiple images to produce an image at a spatially resolved polarization state corresponding to said aerosol substance; wherein the telescope comprises a first telecentric imaging lens group and a wavelength filter positioned in a field image of the first telescope telecentric beam to define a spectral range of interest; the telescope further comprising: a converging lens group converging the beam to a pupil stop; relay optics including a second telecentric imaging lens group arranged to generate a telecentric beam; and splitter optics, comprising a polarization splitter for the selected wavelength range to split the telebeam into polarized beams; a further splitter; and a retarder to create multiple phase stepped images at different polarizations, the detector comprising multiple image sensors positioned in imaging planes after the splitter optics, and said polarization splitter, further splitter and retarder positioned in the telecentric beam of the second telecentric imaging lens group.

Methods for characterizing scattering in a medium of a Light Detection And Ranging (LiDAR) system and systems therefrom are provided. A method includes obtaining off-axis power return characteristics with respect to a first wavelength of light and on-axis power return characteristics for at least the first wavelength of light. The method also includes estimating at least one beam attenuation coefficient (c) based on the off-axis power return characteristics and common volume parameter function for the LiDAR system and an extinction coefficient () for the medium based on the on-axis power return characteristics. The method further includes extracting a value for at least one diffuse attenuation coefficient (K.sub.d) for the medium using a beam spread parameter for the LiDAR system (D) and a pre-defined relationship between , c, D, and K.sub.d.