Abstract: A quadrant detector includes a holographic optical element and a plurality of detector elements. The holographic optical element is designated to have four quadrants, each of which directs radiation incident thereon to an associated detector element. Signals from the detector elements are processed individually to optimise the performance of each detector element.

Abstract: Described herein is a latch circuit (110) which has an improved maximum toggle rate or frequency. The latch circuit (110) includes a first portion (116) and a second portion (62) in which input clock signals (52,54) are applied to respective input transistors (118,78). The input transistor (118) for the first portion (116) has an emitter area which is double that of the input transistor (78) for the second portion (62). This ‘imbalance’ between the two input transistors (118,78) provides an increase in the ‘hold period/follow period’ ratio such that it is greater than 1, the self-resonance of the latch circuit (110) and also maximum toggle rate or frequency.

Abstract: A laser transmitter unit is described, the unit including a laser diode 2 emitting laser radiation into a lens system. The lens system includes collimating lenses L1, L3 and focussing lenses L2, L4. Additionally, compensating or steering lens S1, S2 are positioned between the collimating lenses L1, L3 and the focussing lenses L2, L4. The steering lenses S1, S2 act to reduce the sensitivity of the focussing lenses L2, L4 to position within the lens system. The position of the focussing lenses can be difficult to control, particularly when the lenses are welded into position in the laser transmitter unit 1.