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Determining Distances Especially the Flying Height of Transducers

IP.com Disclosure Number: IPCOM000086129D
Original Publication Date: 1976-Jul-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 68K

Publishing Venue

IBM

Related People

Brezoczky, BO: AUTHOR [+2]

Abstract

The device shown in the figure permits measuring distances between a transparent medium and an opaque item without requiring calculations. To use the device, the item is disposed a distance from the transparent medium. The opaque item is illuminated by a light of a known wavelength from a variable-frequency monochromatic light source through the transparent medium. The light sets up a number of interference fringe lines as a function of the wavelength of the light.

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Determining Distances Especially the Flying Height of Transducers

The device shown in the figure permits measuring distances between a transparent medium and an opaque item without requiring calculations. To use the device, the item is disposed a distance from the transparent medium. The opaque item is illuminated by a light of a known wavelength from a variable- frequency monochromatic light source through the transparent medium. The light sets up a number of interference fringe lines as a function of the wavelength of the light.

The determination of the distance involves identifying the order number of a particular fringe line by noting the location of a fringe line at a known initial wavelength of the light (400 nanometers for this scale layout), and then increasing the wavelength of the light until the neighboring fringe line has moved into the location of the first fringe line. The newly identified line is then positioned over the particular point on the item whose distance from the medium is to be measured.

The device shown in the figure performs the required calculation by setting the cursor line A to the value of the wavelength after a one fringe line shift is completed. Cursor B then indicates the order number of the fringe line in question. That is, the order number is the number of half-wavelengths between the medium and the slider. After the known line is positioned over the point of interest, cursor A is set to the same wavelength value as the wavele...