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Browse Prior Art Database

Focusing of Laser for Maximum Power Density And The Control of a Line Deletion Process

IP.com Disclosure Number: IPCOM000078110D
Original Publication Date: 1972-Nov-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Lavin, AJ: AUTHOR [+3]

Abstract

The drawing shows a system used for observing a surface 3 while machining it with a beam from a laser 5. The planar interconnections can be observed on the screen 7, by light from an external illuminator 9, which is reflected off the surface 3 through a focusing lens system 11 onto screen 7. The same image is reflected onto a TV camera 13 by a beam splitter 15. Although the laser light and surface, topology can now be directly viewed on the TV screen, it is still a problem to know when the laser beam is in focus on the surface, and to determine when sufficient energy has been absorbed to cause a change in material phase.

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Focusing of Laser for Maximum Power Density And The Control of a Line Deletion Process

The drawing shows a system used for observing a surface 3 while machining it with a beam from a laser 5. The planar interconnections can be observed on the screen 7, by light from an external illuminator 9, which is reflected off the surface 3 through a focusing lens system 11 onto screen 7. The same image is reflected onto a TV camera 13 by a beam splitter 15. Although the laser light and surface, topology can now be directly viewed on the TV screen, it is still a problem to know when the laser beam is in focus on the surface, and to determine when sufficient energy has been absorbed to cause a change in material phase.

Using another screen or screens 17, the reflected speckle pattern can be observed. As the surface is moved through the focus, the intensity of the illumination of the screen undergoes a change from a fairly uniform small speckle pattern to a large granular pattern, with large bright and dark interference regions. This indicates that the surface is in focus. If the surface is moved beyond the local point, the pattern reverses to the smaller more uniform speckle. This fact makes it simple to focus the surface accurately.

The system described above uses screen 7 for wide range of field viewing. This is particularly helpful in locating the area or line to be deleted. The speckle pattern observed on screens 17 is due to the reflected light from the area being probed...