Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Scanning Ring Illumination for Laser Processing

IP.com Disclosure Number: IPCOM000038955D
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Goodman, DS: AUTHOR

Abstract

Laser processing is presently being performed at wavelengths well into the UV where there are few suitable optical materials and lenses. As a result, all-reflective optics are used, which have the additional advantage of freedom from chromatic aberration. There are commercially available reflective objectives, constructed with two mirrors as shown in Fig. 1. These objectives have a central obstruction, so that light directed toward their centers does not reach the image plane, as shown in Fig. 2. Thus, there is a reduction in power efficiency. In addition, light hitting the central portion of the mirror is scattered into the optical system, possibly causing detrimental effects. These difficulties can be eliminated in the manner shown in Figs. 3 and 4.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 2

Scanning Ring Illumination for Laser Processing

Laser processing is presently being performed at wavelengths well into the UV where there are few suitable optical materials and lenses. As a result, all- reflective optics are used, which have the additional advantage of freedom from chromatic aberration. There are commercially available reflective objectives, constructed with two mirrors as shown in Fig. 1. These objectives have a central obstruction, so that light directed toward their centers does not reach the image plane, as shown in Fig. 2. Thus, there is a reduction in power efficiency. In addition, light hitting the central portion of the mirror is scattered into the optical system, possibly causing detrimental effects. These difficulties can be eliminated in the manner shown in Figs. 3 and 4. A rotating prism 10 or an equivalent device causes the illumination 12 to be swept in a ring within the acceptance angles of the objective. The only energy lost is the small amount diffracted outside this range. In the time average, this moving spot is equivalent to a ring- shaped noncoherent source. The motion can easily be sufficiently rapid that this equivalence is achieved for any processing work. This method can be used with sources of any type. With coherent laser light, it has the further advantage of eliminating speckle.

1

Page 2 of 2

2

[This page contains 4 pictures or other non-text objects]