Van der Lugt optical correlation for the measurement of leak rates of hermetically sealed packages

Colleen Mary Fitzpatrick; Edward P. Mueller

doi:10.1117/12.51068

1 January 1991 Van der Lugt optical correlation for the measurement of leak rates of hermetically sealed packages

Colleen Mary Fitzpatrick, Edward P. Mueller

Proceedings Volume 1332, Optical Testing and Metrology III: Recent Advances in Industrial Optical Inspection; (1991) https://doi.org/10.1117/12.51068
Event: 34th Annual International Technical Symposium on Optical and Optoelectronic Applied Science and Engineering, 1990, San Diego, CA, United States

Abstract

Van der Lugt optical correlation, involving Fourier transform holography, has been shown to be successful in detecting and accurately measuring leak rates in hermetically sealed packages in the range of 10' to iO6 atm cc/sec. The technique depends on the measurement of the relaxation time of sealed packages under vacuum conditions, from which leak rates can be calculated. This technique has the advantage over conventional 'leak testing, in that it requires no backfilling with tracer gas, and therefore is more cost effective and faster. Also, packages such as pacemakers can be examined at the end of the manufacturing process, after the polymer neck has been inserted, eliminating any absorption of the helium or radioactive tracer gas that normally reduces the accuracy of conventional methods. Furthermore, this new technique can be used to rapidly test packages with large internal free volumes, in that it requires only a small differential pressure across the walls of the package, and avoids measurements depending on slowly changing internal helium or tracer gas concentrations. A comparison will be made between this HNDT technique and other leak testing methods commonly used in the packaging industry, in terms of cost and time factors, and range of accuracy.

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Colleen Mary Fitzpatrick and Edward P. Mueller "Van der Lugt optical correlation for the measurement of leak rates of hermetically sealed packages", Proc. SPIE 1332, Optical Testing and Metrology III: Recent Advances in Industrial Optical Inspection, (1 January 1991); https://doi.org/10.1117/12.51068

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KEYWORDS

Helium

Fourier transforms

Holograms

Holography

Optical testing

Manufacturing

Optical inspection

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