Abstract: An electroptic metrology system uses Moire interferometry to generate contour information on the surface of an object. Interfering coherent beams generate a n image on the object's surface that includes a stripe pattern. The surface is viewed with a high resolution camera and digitized using a frame grabber and computer. A reference pattern is generated in software and is mixed with the digitized object surface signals. The mixed signals are filtered to remove signals at the carrier frequency and signals containing the beat frequency indicative of the surface contours are output.

Abstract: A fiber optic sensor probe system comprises an electromechanical arrangement system which enables a fiber optic probe to lock onto a null point relative to a target which null point represents an in focus condition for the probe relative to the target. A servomechanism feedback circuit maintains the probe in an in focus condition relative to the target if the target moves. A dithering motion is provided to the probe such that, when the electrical output of the probe has a frequency component which is the same frequency as that of the dither, an out of focus condition of the probe relative to the target exists and the servomechanism feedback system operates to correct it. A monochromatic light source is used to eliminate the problem of different spectral components of light having slightly different focal lengths.

Abstract: A method of determining the displacement of a fiber optic sensor from a target in which a first lens is spaced from the target at a first distance an a second lens is spaced from said target at a second distance which provides the greatest intensity response at said first distance and thereafter spacing said first lens from said second lens to provide symmetrical slope values of response.

Abstract: A displacement measuring instrument for measuring the displacement of a target including in combination a fiber optic lens assembly including means for maintaining said assembly in space relation with said target, dither means for vibrating said assembly toward and away from said target about the lens null along the axis of said assembly, first electronic means for providing a first output voltage proportional to displacement of said assembly from said target, second electronic means cancelling that portion of said first output voltage resulting from displacement due to said dither means and providing a second voltage resulting from displacement due to means other than said dither means, servo means receiving said second output voltage and moving said assembly with respect to said target to null said second output voltage and measurement means measuring the movement of said servo means.

Abstract: A method of determining the displacement of a fiber optic sensor from a target in which a first lens is spaced from the target at a first distance an a second lens is spaced from said target at a second distance which provides the greatest intensity response at said first distance and thereafter spacing said first lens from said second lens to provide symmetrical slope values of response.