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Browse Prior Art Database

Optical Scanner With Helical Mirror

IP.com Disclosure Number: IPCOM000043980D
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Deyhle, M: AUTHOR [+2]

Abstract

For deflection along a straight line, a light beam is reflected at a rotating helical mirror whose pitch corresponds to the length of the desired line. In the figure, a laser 1 generates a collimated beam 3, whose intensity can be varied in modulator 2, and whose axis is parallel to the axis of rotation of helical mirror 4. The beam is reflected at helical surface 4a which is oriented at 45Πrelative to the axis, so that the reflected beam is normal to the substrate 5 to be illuminated. One revolution (4b) of helical mirror 4 thus generates a complete scan line on substrate 5 which is subsequently moved in the X-direction for generating another line.

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Optical Scanner With Helical Mirror

For deflection along a straight line, a light beam is reflected at a rotating helical mirror whose pitch corresponds to the length of the desired line. In the figure, a laser 1 generates a collimated beam 3, whose intensity can be varied in modulator 2, and whose axis is parallel to the axis of rotation of helical mirror 4. The beam is reflected at helical surface 4a which is oriented at 45OE relative to the axis, so that the reflected beam is normal to the substrate 5 to be illuminated. One revolution (4b) of helical mirror 4 thus generates a complete scan line on substrate 5 which is subsequently moved in the X-direction for generating another line. An unmodulated beam 3 can be used if substrate 5 contains a pattern to be scanned or if substrate 5, covered with a photoresist, is used in connection with a transmission mask arranged over it. A modulated beam can be used to draw patterns on the very photoresist covering substrate 5. A rotating helical mirror needs no flyback time when a scan line is completed and yet maintains the normal incidence along the entire line, so that imaging errors are minimized. Long scanning lines (of the order of 1 m) can thus be drawn with high precision. The helical mirror can be manufactured by precision milling two cylinder halves which are then made to engage and are periodically rotated for mutual polishing.

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