US 6,147,764 A · Optical interference profiler having shadow compensation

Abstract

In machining such as lapping and polishing, the detection of interference fringes is carried out during the machining, and an interference fringe image of a size sufficient to determine the surface profile is obtained. The workpiece is mounted on a machining mechanism base, and a lapping tool mounted on the workpiece is rotated. The lapping tool has a measurement window and an interferometer is provided above the workpiece via the lapping tool. The interferometer captures plural interference fringe images at different positions of the measurement window, each including fringe images of the measurement window areas and shadow images of the areas obstructed by the lapping tool. The shadow images are eliminated from the interference fringe images on the basis of the reference value for the optical intensity of the shadow image, and the fringe images of the measurement window areas are synthesized to form consecutive synthesized interference fringe images for a wide range of interference fringes.

Claims14

Dependent claims

An optical interference measurement device for optically measuring an interference of a target workpiece to be held in a machining device and machined by a machine tool, said optical interference measurement device comprising:

a machine tool having a measurement window which penetrates the machine tool;
interference image formation means for irradiating the machine tool with measurement light from the side opposite to the workpiece to capture a plurality of optical interference images which are present in the range including said measurement window and which have different positional relationships between the workpiece and the measurement window;
and
image processing means for synthesizing the fringe images of the workpiece obtained in the measurement window area of said plural optical interference images to form a synthesized interference fringe image in which the interference fringe images are consecutive within a predetermined measurement range;
said image processing means eliminating the shadow of the machine tool from the optical interference image on the basis of a reference tool shadow intensity which is the reference size of the optical intensity of the tool shadow corresponding to the tool section in the optical interference image to form said synthesized interference fringe image.

2 more elements

An image processing device for an optical interference measurement device which processes optical interference images of a workpiece photographed through a measurement window which penetrates a machine tool of a machining device from the side opposite to the workpiece, said image processing device comprising:

input means for inputting plural optical interference images having respectively different positional relationships between the workpiece and the measurement window;
and
image processing means for synthesizing the fringe images of the workpiece obtained at the measurement window sections of said plural optical interference images to form a synthesized interference fringe image in which interference fringes are consecutive in a predetermined measurement range, said image processing means eliminating tool shadows from optical interference images on the basis of the reference tool shadow intensity which is the reference size of the optical intensity of the tool shadows corresponding to the tool portions in the optical interference image to form said synthesized interference fringe image.

Dependencies are inferred from the claim text.

Optical interference profiler having shadow compensation

Life of this patent

Optical interference profiler having shadow compensation

Life of this patent

Abstract

Claims14