Optical translation measurement

Apparatus for measuring relative motion between the apparatus and a surface comprising:

• an illumination source, which transmits illumination to illuminate the surface;
• a first detector which receives illumination from the source after its reflection from the surface;
• an object which reflects a portion of the illumination from the illumination source to said first detector, such that the first detector generates a first signal based on coherent detection of the illumination reflected from the surface with the illumination, that is reflected by the object, functioning as a local oscillator;
• a second detector which receives illumination from one of the object and the surface without receiving illumination from the other of the surface and the object and generates a second signal responsive thereto;
• a signal corrector that adjusts the first signal for changes in the intensity of the illumination, based on the second signal;
• and
• a motion calculator that calculates the relative motion responsive to the signal from the signal corrector.

A method for determining the relative motion of an optically diffuse surface with respect to a measurement device comprising:

• illuminating the surface with incident illumination from a laser source, such that illumination is reflected from portions of the surface;
• diffracting part of the illumination utilizing a grating, which is part of the measurement device, to form reference illumination;
• coherently detecting the illumination reflected from the surface utilizing the reference illumination as a local oscillator to form a signal;
• and
• determining the quantity of relative motion of the surface parallel to the grating from the signal.

A method for determining the relative motion of a surface with respect to a measurement device comprising:

• illuminating the surface with linearly polarized incident illumination from a laser source, such that illumination is reflected from portions of the surface;
• polarizing the reflected illumination;
• coherently detecting the reflected illumination from the surface utilizing reference illumination derived from the laser source as a local oscillator to form at least two signals;
• determining the quantity of relative motion of the surface utilizing the at least two signals.

Apparatus for measuring motion relative to a surface, comprising:

• at least one laser that illuminates the surface;
• at least one object that reflects or diffracts a portion of the illumination to at least three directions in space to act as local oscillator illuminations;
• at least three detectors each of which coherently detects illumination reflected from the surface utilizing the local oscillator beams to form at least three signals responsive to the motion of the apparatus relative to the surface;
• and
• circuitry that determines the motion of the apparatus with respect to the surface from the signals,
• wherein the at least three detectors comprise at least three detector pairs and wherein the at least three signals comprise at least quadrature-pair signals.

Apparatus for measuring motion relative to a surface, comprising:

• at least one laser than illuminates the surface;
• at least one object that reflects or diffracts a portion of the illumination to at least three directions in space to act as local oscillator illuminations;
• at least three detectors each of which coherently detects illumination reflected from the surface utilizing the local oscillator beams to form at least three responsive to the motion of the apparatus relative to the surface;
• circuitry that determines the motion of the apparatus with respect to the surface from the signals;
• and
• a polarizer that polarizes the illumination reflected from the surface.