Device for determining distance interferometrically

A system, comprising:

• a first plate;
• a second plate arranged substantially in parallel to the first plate;
• a device adapted to interferometrically determine a vertical distance between the first plate and the second plate, including:
• 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 the 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 the 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;
• and
• the 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.

A method for interferometrically determining a vertical distance between two plates arranged substantially in parallel, comprising:

• emitting, by a light source, a beam of rays that falls in inclined fashion upon a beam-splitter element on a first plate;
• splitting the beam of rays a reflected reference beam of rays and a transmitted measuring beam of rays;
• striking the measuring beam of rays on a reflector element on a second plate;
• reflecting the measuring beam of rays in a first reflection back in a direction of the first plate;
• passing the reference beam of rays through a first deflection element;
• passing the measuring beam of rays through a second deflection element;
• subsequently passing the reference beam of rays and the measuring beam of rays through an assigned retroreflector being arranged separately from the first plate and the second plate;
• traversing the measuring beam of rays through a third deflection element and the reference beam of rays through 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;
• reflecting the reference beam of rays at the first plate;
• reflecting the measuring beam of rays in a second reflection back at a reflector element of the second plate;
• propagating the measuring beam of rays and the reference beam of rays collinearly in a direction of a detection unit;
• and
• generating, by the detection unit, a plurality of phase-shifted distance signals from interfering measuring and reference beams of rays.