Abstract: A method of and apparatus for testing the chamber of a test part for leaks in which the chamber is filled with gas under pressure and the differential pressure drop over a predetermined interval of time is determined. The temperature of the part being tested is determined, and a storage table of correction values corresponding to the estimated differential pressure drop attributable to the temperature of the part is provided. The correction value for the temperature of the part is selected from the storage table and substracted from the measured differential pressure drop to obtain a corrected differential pressure drop. If the corrected differential pressure drop is within a range below a predetermined amount, a fraction of it is summed back to the storage table to adjust the selected correction value.

Abstract: Apparatus for fixturing an optical recording disc in a DRAW recording machine comprising a hub having a conical shoulder for receiving and locating the disc center opening, and an axially facing shoulder for nesting support of the recording disc. A retaining ring encircles the disc periphery and has an inwardly oriented lip for capturing the disc periphery. A resilient snubber of elastomeric construction extends from the hub to the ring and has a roughened axially facing surface spaced from the opposing surface of the disc. A knob, including a torque-isolating thrust bearing, clamps the hub to the drive spindle of a recording apparatus. In operation, the snubber and air space between the snubber and disc cooperate to dampen vibration of the recording disc for enhanced accuracy and reliability of the recording process.