Browse Prior Art Database

Calibration Fixture for Evaluating Illumination Conditions

IP.com Disclosure Number: IPCOM000100400D
Original Publication Date: 1990-Apr-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Cipolla, TM: AUTHOR [+2]

Abstract

Disclosed is a device for evaluating an illuminator for precision machine vision applications consisting of multiple light sources.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 68% of the total text.

Calibration Fixture for Evaluating Illumination Conditions

       Disclosed is a device for evaluating an illuminator for
precision machine vision applications consisting of multiple light
sources.

      This device shown in Fig. 1 consists of an array of polished
spheres pressed fit into a support plate that has a thickness
slightly greater than the radius of the spheres. The spheres are
obtained from balls used in the manufacture of ball bearings.  When
this object is illuminated using nearly grazing illumination from a
multiple light source, the reflected images of the spheres can be
analyzed to gain information about the light source.  Fig. 2 shows a
side view of this device, indicating the direction of incident and
reflected light.  Information derived from images of the calibration
fixture is used to assist an operator in making mechanical
adjustments to the illuminator.  For example, each reflected spot
from a single sphere can be compared for relative intensity and the
light source adjusted until each spot has an equal intensity.

      Other information can also be derived from images of this
calibration fixture.  In the case of multiple, relatively small
illumination sources that must be oriented in a specific pattern: (1)
the centroids of each of these source images could be analyzed and
used to compute relative source position errors and (2) intensity
profiles of an individual source would indicate the degree of
uniformity of that source.  Al...