GB1276081A - Improvements in or relating to proximity sensing devices - Google Patents

Abstract

1276081 Proximity fuze EMI Ltd 20 Aug 1966 [20 Aug 19651 35922/65 Heading F3A [Also in Division H1] A proximity fuze for an anti-aircraft missile includes a stimulated semi-conductor body, emissions from the body being reflected back by the target to the missile to operate it. As shown in Fig. 1, stimulated emissions from an infra-red radiation generator 1 provided by a Gallium Arsenide diode are focused by an optical system 2 into a beam for illuminating a target 4. The generator 1 is caused to emit a radiation pulse by means of a modulator circuit 3. Fig. 3 shows an example of the modulator circuit in which the GaAs diode 1 is connected in the emitter circuit of an avalanche transistor 20, the latter being caused to discharge a pulse forming delay line 21 through the diode at the appropriate time. The modulator also contains a timing circuit to ensure emission of pulses at appropriate instances in time. A modified modulator circuit (Fig. 4, not shown) includes a spark gap which is triggered. Reflected radiation from the target 4 is transmitted by optical system 5 to a silicon diode 6, the signal being amplified at 7 and applied to one input of a gate 8. The gate 8 is opened by the pulse from modulator 1 after passing through a delay 9, whereby only those signals resulting from reflections which are received from a target within a predetermined range are passed to the amplifier 10 and thence to a firing circuit 11. In a modified system (Fig. 5, not shown), the transmit and receive optics are laterally displaced by a specified distance to provide two converging beams which overlap each other at a distance from the missile, the system operating only when a target appears in the overlapping area.