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Optical Glass Properties

Indars optical interferometer

Flatness Measurements
Patented, the non-contact Indars optical interferometer was conceived at Valley Design because there were no reasonably priced instruments on the market which could accurately measure the flatness of polished thin transparent wafers, substrates, plates and windows.

Glass Wafer Flatness Measurement Interferometer

Indars Interferometer

In developing this optical instrument, several other basic problems needed to be solved. One of these was how to fixture and hold thin wafers such that the influence of gravitational force would be minimized. Also, the holding mechanism needed to be designed so that it would not add unnecessary stresses to the thin, fragile part to be measured.

Another important consideration was designing a uniform intensity light source with a working wavelength corresponding to the yellow line of the Sodium spectrum.

Finally, the instrument need to measure wafer sizes as large as 300mm in diameter.

All of the above considerations have been incorporated in the new Indars Optical Interferometer.

Surface topography and flatness measurement instrument related web pages:

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