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Measurement of Small Dielectric Gaps

IP.com Disclosure Number: IPCOM000076133D
Original Publication Date: 1972-Jan-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Nafarrate: AUTHOR [+2]

Abstract

Small dielectric gaps are usually measured by optical methods, such as white light (Newton Rings) interferometry or monochromatic light interferometry. The main disadvantages of these conventional interferometric methods is the uncertainty in determining the interference order, and the resolution, limiting the spacing measurement at smaller gaps for the monochromatic scheme, and at larger gaps for the white light scheme. Furthermore, the identification of color fringes in the Newton's rings method is subject to error, due to either photographic or physiological insensitivities. It has been found that the uncertainty is removed by observing the rings with a spectroscope that quickly shows the missing or interfering wavelengths.

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Measurement of Small Dielectric Gaps

Small dielectric gaps are usually measured by optical methods, such as white light (Newton Rings) interferometry or monochromatic light interferometry. The main disadvantages of these conventional interferometric methods is the uncertainty in determining the interference order, and the resolution, limiting the spacing measurement at smaller gaps for the monochromatic scheme, and at larger gaps for the white light scheme. Furthermore, the identification of color fringes in the Newton's rings method is subject to error, due to either photographic or physiological insensitivities. It has been found that the uncertainty is removed by observing the rings with a spectroscope that quickly shows the missing or interfering wavelengths. The fringe order is easily determined and an extension of the upper limit of the white light method is accomplished.

The physical arrangement comprises a direct vision spectroscope 1, with eyepieces 2 and beam splitter 3, microscope 4, beam splitter 5, white light source 6, and the di-electric gap 7 to be measured between transparent plates 8. Optionally, camera 9 may be used.

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