Abstract: A method of detecting optical subsystem failures includes emitting a pulsed light beam from a laser through a window. A reflection signal indicative of a portion of the beam reflected by the window is compared to an expected signal to monitor for degradation of an optical component.

Abstract: A method of detecting optical subsystem failures includes emitting a pulsed light beam from a laser through a window. A reflection signal indicative of a portion of the beam reflected by the window is compared to an expected signal to monitor for degradation of an optical component.

Abstract: A method of optically determining the presence of volcanic ash within a cloud comprises emitting a circularly polarized illuminating beam within a cloud and analyzing backscatter light to identify the presence of volcanic ash within the cloud. The method further includes determining the degree to which the cloud has altered the polarization state of the emitted beam. The index of refraction of the backscatter light and the opacity of the backscatter light are also analyzed.

Abstract: A method of optically determining the presence of volcanic ash within a cloud comprises emitting a circularly polarized illuminating beam within a cloud and analyzing backscatter light to identify the presence of volcanic ash within the cloud. The method further includes determining the degree to which the cloud has altered the polarization state of the emitted beam. The index of refraction of the backscatter light and the opacity of the backscatter light are also analyzed.

Abstract: In one aspect, methods of determining a size distribution of water droplets in a cloud are described herein. In some embodiments, a method of determining a size distribution of water droplets in a cloud comprises sampling a depth of the cloud with a beam of electromagnetic radiation, measuring a scattering signal of the electromagnetic radiation returned from the cloud over a range of field of view angles to provide a measured scattering curve [ptotal(?)], removing a portion of the measured scattering curve, replacing the removed portion with an extrapolation of the remaining measured scattering curve to provide an estimated scattering curve, and determining a first estimate droplet size distribution [n(1)(D)] from the estimated scattering curve.

Abstract: In one aspect, methods of determining a size distribution of water droplets in a cloud are described herein. In some embodiments, a method of determining a size distribution of water droplets in a cloud comprises sampling a depth of the cloud with a beam of electromagnetic radiation, measuring a scattering signal of the electromagnetic radiation returned from the cloud over a range of field of view angles to provide a measured scattering curve [ptotal(?)], removing a portion of the measured scattering curve, replacing the removed portion with an extrapolation of the remaining measured scattering curve to provide an estimated scattering curve, and determining a first estimate droplet size distribution [n(1)(D)] from the estimated scattering curve.

Abstract: In one aspect, methods of determining a size distribution of water droplets in a cloud are described herein. In some embodiments, a method of determining a size distribution of water droplets in a cloud comprises sampling a depth of a cloud with a beam of electromagnetic radiation, measuring echo intensities of the electromagnetic radiation returned from the cloud with a detector, determining a measured optical extinction coefficient from the measured echo intensities, determining a measured backscatter coefficient from the measured echo intensities, determining a lidar ratio from the measured optical extinction coefficient and the measured backscatter coefficient, determining from the lidar ratio a value pair comprising a shape parameter (?) and median volume diameter (DMVD) of the water droplets, and determining a size distribution of the water droplets using the value pair (?, DMVD).

Abstract: A method of detecting contaminants on a window surface of a viewing system comprises the steps of: reflecting light off of contaminants on the window surface; capturing the reflected light in an image; converting the image into image data; and processing the image data to detect the contaminants on the window surface. Also, apparatus for detecting contaminants on an external surface of a window of a viewing system comprises: at least one light source for reflecting light from contaminants on the external surface; an imager for capturing an image of the reflected light and converting the image into image data; and a processor for processing the image data to detect the contaminants on the external surface.

Abstract: A method of detecting a combustion chemical in a region and setting an alarm based on concentration levels of the combustion chemical comprises the steps of: monitoring the region for a combustion chemical with a sensor having a measurable parameter which changes in value proportional to concentration levels of the monitored combustion chemical, the measurable parameter being ambient temperature dependent; generating an ambient temperature measurement of the sensor; reading the measurable parameter and ambient temperature measurement; processing the measurable parameter and ambient temperature measurement readings to generate a temperature compensated concentration level of the monitored combustion chemical; and setting an alarm based on the generated temperature compensated concentration level. A fire detector unit for implementing the foregoing described method is also disclosed.

Abstract: A method of detecting a combustion chemical in a region and setting an alarm based on concentration levels of the combustion chemical comprises the steps of: monitoring the region for a combustion chemical with a sensor having a measurable parameter which changes in value proportional to concentration levels of the monitored combustion chemical, the measurable parameter being ambient temperature dependent; generating an ambient temperature measurement of the sensor; reading the measurable parameter and ambient temperature measurement; processing the measurable parameter and ambient temperature measurement readings to generate a temperature compensated concentration level of the monitored combustion chemical; and setting an alarm based on the generated temperature compensated concentration level. A fire detector unit for implementing the foregoing described method is also disclosed.

Abstract: A method of detecting a fire in a scene by infrared (IR) radiation image processing comprises the steps of: receiving a sequential plurality of IR radiation images of the scene, each image including an array of picture elements (pixels), each pixel having a value that is representative of the pixel's portion of IR radiation intensity in the array of the scene image; identifying a region of pixels in one image based on pixel values; tracking the region through images subsequent the one image to determine a change of the region that meets predetermined IR radiation criteria; and detecting the fire in the scene based on the determined change of the region. In one embodiment, the step of tracking includes the steps of: identifying the region in images subsequent the one image; and comparing the identified regions of the one and subsequent images to determine a change of the region that meets the predetermined IR radiation criteria.