An Active Optical Ground Sensor for a Parachute Retrorocket Airdrop System (Prads),
Abstract
An active optical ground sensor for a Parachute Retrorocket Airdrop System (PRADS) was evaluated. The sensor yields a fire pulse for retrorocket initiation when the sensor (attached to a dropload platform) is at a predetermined distance above the ground. The senor employs triangulation and geometric ranging with a gallium arsenide laser. A fire pulse is produced when the ground surface enters a well defined detection region of small spatial extent located at the desired function range from the sensor. Drop tests of a sensor unit with a 6-in. transmitter-to-receiver lens separation showed that the sensor functioned within + or - 1 ft of the preset function height of 28 ft over a variety of ground surfaces including light dirt, sod, green shrub leaves, and sod covered with a light smoke screen. The accuracy with which the sensor indicates the function height to a point on the ground surface can be further improved by increasing the transmitter-to-receiver lens separation. Laboratory range-response measurements showed that a sensor with a 15-in. lens separation is capable of indicating a function height of 28 ft within + or - 1/2 ft for any target whose reflectance (at 0.9 micrometer) is between rho = 0.05 and rho = 0.8
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1973
- Accession Number
- AD0911216
Entities
People
- Anthony J. D'onofrio
- Reinhard R. Ulrich
Organizations
- Harry Diamond Laboratories