Two color multiple beam interferometer for measuring small separations

• US 3,359,851 A
• Filed: 04/29/1964
• Issued: 12/26/1967
• Est. Priority Date: 04/29/1964
• Status: Expired due to Term

• Current Assignee: Lewis D. Lipschutz, Tseng K. Chow
• Original Assignee: Lewis D. Lipschutz, Tseng K. Chow
• Inventors: Lipschutz, Lewis D., Chow, Tseng K.
• Application Number:
  US04/363,368
• Time in Patent Office: 1,336 Days
• US Class Current: 356/505
• CPC Class Codes: G01B 11/14 for measuring distance or clearance between spaced objects or spaced apertures G01B11/26 takes precedence; rangefinders G01C3/00
• CPC Class Codes: G01B 9/02027 Two or more interferometric channels or interferometers
• CPC Class Codes: G01B 9/02057 by using common path configuration, i.e. reference and object path almost entirely overlapping
• CPC Class Codes: G01B 9/02087 Combining two or more images of the same region
• CPC Class Codes: G01B 9/0209 Low-coherence interferometers

Claims

1. AN APPARATUS FOR DIRECTING LIGHT THROUGH A TRANSPARENT SUBJECT TO A NEARBY SURFACE OF A REFLECT SUBJECT IN SUCH A WAY THAT INTERFERENCE PATTERNS APPEAR IN THE LIGHT REFLECTED FROM THE SURFACE OF THE REFLECTIVE SUBJECT AND THE NEARBY SURFACE OF THE TRANSPARENT SUBJECT ACCORDING TO THE SEPARATION BETWEEN THE SURFACES AND THE WAVELENGTH OF THE LIGHT, THE SURFACES BEING ILLUMINATED IN ONE REGION WITH A LIGHT OF ONE COLOR AND IN AN ADJOINING REGION WITH A LIGHT OF A DIFFERENT COLOR WHEREBY LINES IN THE INTERFERENCE PATTERN CORRESPONDING TO DIFFERENT COLORS WHICH COINCIDE SIGNIFY A PREDETERMINED ABSOLUTE VALUE OF THE SEPARATION BETWEEN THE TWO SUBJECT SURFACES, COMPRISING, A MIRROR HAVING TWO SURFACES MEETING ALONG A KNIFE EDGE;

AN OPTICAL SYSTEM ARRANGED TO FOCUS THE IMAGE OF SAID KNIFE EDGE ON SAID SURFACES OF SAID SUBJECTS IN SUCH A WAY THAT INTERFERENCE PATTERNS APPEAR IN THE LIGHT REFLECTED FROM THE SUBJECT SURFACES;

MEANS TO ILLUMINATE ONE OF SAID MIRROR SURFACES WITH LIGHT OF A FIRST COLOR AND TO ILLIMINATE THE OTHER OF SAID MIRROR SURFACES WITH LIGHT OF A DIFFERENT COLOR, WHEREBY THE REGION OF SAID SUBJECT SURFACES ON ONE SIDE OF THE IMAGE OF SAID KNIFE EDGE IS ILLUMINATED IN SAID FIRST COLOR AND THE REGION OF SAID SUBJECT SURFACES ON THE OTHER SIDE OF SAID IMAGE OF SAID KNIFE EDGE IS ILLUMINATED IN SAID OTHER COLOR;

A CAMERA POSITIONED TO PHOTOGRAPH THE SUBJECT SURFACES TO PRODUCE A RECORD OF THE INTERFERENCE PATTERN.