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Diffuse Reflected-Light Illuminator

IP.com Disclosure Number: IPCOM000040873D
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Goodman, DS: AUTHOR

Abstract

Diffuse illumination is highly desirable in many optical in- spection applications. Difuse light "flattens" images, reducing t shadows due to topography. It also reduces noise due to the glints of light reflected from granular materials (e.g., additive copper). There is not, however, a fully satisfactory diffuse illuminator. Fluorescent lamps provide the most diffuse illumina- tion that is easily obtainable, but they suffer from several drawbacks, the most important being their low power and the limited spectra.

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Diffuse Reflected-Light Illuminator

Diffuse illumination is highly desirable in many optical in- spection applications. Difuse light "flattens" images, reducing t shadows due to topography. It also reduces noise due to the glints of light reflected from granular materials (e.g., additive copper). There is not, however, a fully satisfactory diffuse illuminator. Fluorescent lamps provide the most diffuse illumina- tion that is easily obtainable, but they suffer from several drawbacks, the most important being their low power and the limited spectra.

This publication describes an inexpensive diffuse illuminator number with a number of salutary features. This device makes use of a standard fiber ring illuminator and two cylindrical reflector Fibers in ring illuminators are pointed inward as shown in Fig. 1, in order to produce a uniform field of light at some working distance. In the new illuminator, as shown in Fig. 2, a shiny cylinder within the ring reflects the light from the fiber illuminator onto a diffusely reflecting cylinder on the outside of the ring. The light is then reflected toward the object from a wide range of angles. The range of illumination angles is determined by the lengths of the cylinders and can be easily

(Image Omitted)

adjusted, as shown in Fig. 3. The two reflectors need not be of "optical quality"; simple aluminum cylinders, for example, with low tolerances are satisfactory. In addition, the alignment of the assembly is not critical.

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