GB1379078A - Indication of the passing of a gunnery projectile through an area in space - Google Patents

Abstract

1379078 Target practice aid AUSTRALASIAN TRAINING AIDS PTY Ltd 20 Jan 1972 [21 Jan 1971] 2878/72 Heading H4D [Also in Division F3] In air to air target practice the firer of the missile is given an indication as to whether the missile has passed through the target area by means of detecting reflections from the missile of a beam of light irradiating the target area or an area in front of the target. The beam of light can be stationary (Fig. 1), with a fan shape wide enough to fill the area, or it may be narrow and be scanned through the area (Fig. 2). In the system of Fig. 1, Helium/Neon laser 1 transmits 95-99% of its beam through a semi-reflecting quartz mirror 3 to a perspex light guide 5, Fig. 3, which broadens out the beam in to a flat fan 8. A reflection from a missile travels back through the light guide and is reflected by mirror 3 to a PIN diode 15 via interference rejecting filter 12. In the system of Fig. 2, the fan laser beam from light guide 5 is reflected off of a four sided rotating mirror drum 32 to give four scans of the area in front of the target, Fig. 6. Threshold detectors for the reflected signals determine upper and lower range limits for the swept area. A disc 36 rotating with the drum has a series of coded holes through which a diverted part of the laser beam passes to give coded pulses 54 defining the sweep angle of the beam. A three gate arrangement, Fig. 8 (not shown), with the gates sequentially enabled for successive thirds of the beam scan period enables the determination of "left of target", "hit" and "right of target". The thus analysed reflection signals are then stored for subsequent information transmission to the firer.