an electronics arrangement including an optical emitter and an optical receiver, said optical receiver having an axis of reception, said optical emitter being configured to emit a first beam along an axis of emission in an emission direction, the axis of emission diverging in the emission direction from the axis of reception at an angle of at least two degrees, said emitter having an emission cone and said receiver having a reception cone, the emission cone and the reception cone being nonintersecting, adjacent edges of the emission cone and the reception cone being substantially parallel, said electronics arrangement being configured to be mounted in association with one of a first surface of the object and a second surface of a structure disposed in opposition to the first surface; and

a reflector arrangement including at least one reflective surface, said reflector arrangement being configured to be mounted in association with an other of the first surface and the second surface, said at least one reflective surface being configured to receive at least a portion of the first beam and produce a second beam directed at and received by said optical receiver.