Microinterferometer for distance measurements

A microinterferometer comprising:

• means for reflecting a first portion of an incident light and transmitting a second portion of the incident light, such that the second portion of the incident light is diffracted;
• means for focusing the second portion of the incident light on a predetermined local distance;
• and
• means for receiving interference patterns produced from the first portion of the incident light and the second portion of the incident light, wherein the second portion of the incident light has been reflected from an object surface.

A microinterferometer for measuring the absolute distance to an object surface, the microinterferometer comprising:

• a substrate;
• at least a first diffracting micro-objective comprising said substrate;
• and
• a photo-detector for receiving interference patterns produced from a first portion of an incident light reflected from each diffracting micro-objective and a second portion of the incident light reflected from the object surface.

A diffracting micro-objective comprising:

• a substrate;
• a phase-sensitive, reflective diffraction grating formed on said substrate, said diffraction grating being configured to reflect a first portion of an incident light and transmit a second portion of the incident light, such that the second portion of the incident light is diffracted;
• and
• a lens formed on said substrate for focusing the second portion of the incident light to a predetermined local distance.

A method for measuring the absolute distance to a target surface, the method comprising:

• illuminating the target surface with an incident light beam through a phase-sensitive, reflective diffraction grating, such that a first portion of the incident light beam is reflected and a second portion of the incident light beam is diffracted upon being transmitted through the diffraction grating;
• focusing the second portion of the incident light beam to a predetermined focal distance;
• receiving interference patterns produced from the first portion of he incident light beam reflected from the diffraction grating interfering with the second portion of the incident light beam reflected from the target surface;
• and
• measuring the intensity of the interference patterns to determine the absolute distance.