Medar, Inc.

Mitchell G Van Ochten

Matthew P Frazer

Yongxing Wang

Raymond Mailhot

A method is provided for calibrating a tilt inspection system and a reference disk assembly for use therein wherein a mirror disk of the assembly is attached to a rotatable member of the system by a beveled washer so that the mirror disk rotates at a predetermined tilt angle with respect to an axis of rotation of the rotatable member. As the reference disk assembly is rotated by the tilt inspection system at a relatively slow and constant angular velocity, a beam of light is reflected off the mirror disk to a position sensitive detector (i.e., PSD) and subscribes a circle on the face of the PSD. The tilt inspection system samples the channels from the PSD throughout one revolution of the mirror disk. Calibration or reference data is calculated in the form of tilt transformations. Four basic steps are involved: 1) acquisition of PSD voltage data when the reference disk assembly is rotated within the tilt inspection system; 2) analysis of the data to determine location of a reference marker formed on the mirror disk; 3) fitting of the data to sine functions; and 4) computing the tilt transformations. This approach provides a simple, highly accurate, calibration procedure that minimizes chances for operator error and the affects of system noise.

Method for calibrating a tilt inspection system and reference disk

A method and system are provided for tuning a drive to its coupled stepper motor to minimize motor resonance wherein an electronic accelerometer is mounted in a coupler such as a slip clutch to sense angular accelerative forces of an output shaft of the motor. The slip clutch is slid over the output shaft to permit rapid coupling to and decoupling from the output shaft. The slip clutch is preferably spring-loaded to allow for a relatively constant grip to the output shaft over a normal range of shaft tolerances. A signal generated by the accelerometer is processed to obtain an output signal which is displayed to indicate variations in the angular accelerative forces. The drive is then adjusted to reduce the motor resonance based on the displayed variations.

Method and system for tuning a drive to its coupled motor to minimize

A method and system are provided for measuring a two-dimensional deflection angle of a beam of light reflected from a disk having unknown radial and tangential tilt components by first generating reference data relating to known tilt of a reference disk and then processing the reference data with electrical signals from a two-dimensional photodetector to obtain values related to the deflection angle and the unknown radial and tangential tilt components. The photodetector is preferably a semiconductor photodiode having an active area which measures position of radiant energy in a spot of light focused in a detector plane by a focusing lens. A signal processor including a computer system programmed in accordance with a software algorithm compensates for interaction between X and Y axes of the active area of the photodiode to compensate for alignment errors or tolerances, not only up, down, left and right, but also for rotational errors as well. In this way, the method and system can utilize a single small, relatively low cost semiconductor photodiode for both radial and tangential measurements of the same spot of light.

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Livonia, MI, United States of America

Mitchell G Van Ochten