Abstract: Apparatus and associated methods relate to improving measurement of metrics of air data of an atmosphere outside an aircraft. Such measurements are improved by estimating a daylight portion of light received by an optical receiver configured to receive a reflected portion of the projected beam backscattered by the atmosphere. Estimation of the daylight portion is performed using a daylight filter. The daylight filter receives the light received by the optical receiver after it has been filtered by a vapor cell filter and separates the light, as filtered, into a beam sampling portion and a complementary non-sampling portion. The non-beam sampling portion includes wavelengths immediately adjacent to the beam sampling portion. The non-beam sampling portion is used to estimate the daylight portion within the beam sampling portion, which also contains the reflected portion of the projected beam used for calculating the metrics of air data.

Abstract: Apparatus and associated methods relate to improving measurement of metrics determined by laser air-data systems subject to unwanted background light. Such measurements are improved by estimating and excising the unwanted background light from the total light received by an optical receiver which receives a Doppler-shifted reflected portion of a projected beam of light backscattered by aerosols and air molecules of an atmosphere. The background light is estimated using a background-light rejection filter that receives the light received by the optical receiver after it has been filtered by a vapor cell filter and separates the light received by the optical receiver into a beam sampling portion and a complementary non-beam portion. The non-beam sampling portion is used to estimate the background light portion within the beam sampling portion, which also contains the Doppler-shifted reflected portion of the projected beam used for calculating the metrics of air data.

Abstract: Apparatus and associated methods relate to measuring metrics of a contrail produced by an aircraft engine. To measure such metrics, a beam of light is projected into a projection volume that intersects an exhaust path of the aircraft engine. Light from a reception volume that intersects the exhaust path of the aircraft engine is received. An intersection volume is formed by an intersection of the reception volume and the projection volume. The light received includes a reflected portion of the projected beam backscattered by the atmosphere from within the intersection volume. The reflected portion of light received is used to determine whether a contrail is forming within the intersection volume. An alert is generated in response to determination that a control is forming within the intersection volume.

Abstract: An optical apparatus can be configured to cover an optical transceiver. At least a portion of the apparatus can be configured to move relative to the transceiver between a block state wherein the apparatus is configured to block transmission from a transmitter of the optical transceiver to a receiver of the optical transceiver as well as block emission from the transmitter to the atmosphere, and one or more transmit states wherein the apparatus is configured to allow at least partial transmission from the transmitter of the optical transceiver to a receiver of the optical transceiver while blocking emission from the transmitter to the atmosphere.