Abstract: An optical reflectometer includes an optical head having a measuring chamber defined therein and a measuring zone defined within the chamber. A pair of non-parallel bores are defined within the front wall of the head and optically lead into the measuring chamber so as to intersect at the measuring zone. A light source is optically associated with one of the bores while a photodetector is optically associated with the other one of the bores. A carrier, having a cut-away section defined within its front wall for accommodating the light path defined by the light source, the measuring zone, and the photodetector, is removably disposed within the optical head and serves to carry, and position, a test object with respect to the measuring zone, the object, in turn, being removably disposed within the carrier.

Abstract: An engine driven reciprocating air compressor. The engine is operated in a through scavenge two-stroke mode. The engine has opposed pistons reciprocating in opposition in a cylinder, the pistons being rigidly connected to respective compressor pistons working in compressor cylinders. A crankshaft rotates about an axis perpendicular to and intersecting the engine cylinder axis. The piston pairs are directly coupled to the crankshaft by connecting rods. The crankshaft synchronizes the piston pairs, defines their strokes, and provides rotary motion for auxiliary devices. The connecting rods and crankshaft are lightweight and do not transmit full engine power. The piston pairs are provided with inward return energy from a flywheel on the crankshaft and air trapped in compressor cylinder clearance volumes. The inward faces of the compressor pistons may be used to compress fuel/air mixture to the scavenge pressure.