Device for determining distance interferometrically

摘要

A device for interferometrically determining the distance between two plates disposed substantially in parallel, includes a light source, beam-splitter element(s), reflector element(s), deflection elements, retroreflectors, and a detection unit. A beam of rays emitted by the light source falls on the first plate and splits into a reflected reference beam of rays and a transmitted measuring beam of rays. The measuring beam strikes a reflector on the second plate and undergoes a first reflection back toward the first plate. The reference beam traverses a first deflection element, and the measuring beam traverses a second deflection element. Both beams pass through a retroreflector. The reference beam is reflected at the first plate, and the measuring beam undergoes a second reflection at a reflector of the second plate, so that both beams propagate collinearly interferingly toward the detection unit, where a plurality of phase-shifted distance signals are generated.

主权项

1. A device for interferometrically determining a vertical distance between two plates arranged substantially in parallel, comprising:
a light source; at least one beam-splitter element; at least one reflector element; a plurality of deflection elements; a plurality of retroreflectors; and a detection unit; wherein the light source is adapted to emit a beam of rays that falls in inclined fashion upon a beam-splitter element on a first plate and is split into a reflected reference beam of rays and a transmitted measuring beam of rays, so that:
the measuring beam of rays strikes a reflector element on a second plate and undergoes a first reflection back in a direction of the first plate;the reference beam of rays passes through a first deflection element and the measuring beam of rays passes through a second deflection element, the reference and measuring beams of rays each subsequently pass through an assigned retroreflector being arranged separately from the first plate and the second plate, and the measuring beam of rays then traverses a third deflection element and the reference beam of rays traverses a fourth deflection element, both the first and second deflection elements and the third and fourth deflection elements in each case producing different deflection effects on the traversing reference and measuring beams of rays;the reference beam of rays is then reflected at the first plate;the measuring beam of rays then undergoes a second reflection back at a reflector element of the second plate; andthe measuring beam of rays and the reference beam of rays then propagate collinearly in a direction of the detection unit, the detection unit adapted to generate a plurality of phase-shifted distance signals from interfering measuring and reference beams of rays.