Method for automatically adjusting the levels of illumination sources in an optical measurement machine

A method comprising:

• on a first optical inspection system,
• (a) determining and storing a desired illumination level for a reference light source at a plurality of zoom magnifications m,
• (b) determining a desired illumination level for a first illumination light source at each of said plurality of zoom magnifications m, and
• (c) calculating and storing the ratio of illumination light source intensity to a reference light source intensity at each of said plurality of magnifications m;
• and
• on a second optical inspection system:
• (d) determining desired illumination levels for a reference light source at a plurality of zoom magnifications m, and
• (e) for a desired zoom magnification, setting the intensity of a first illumination light source to a value substantially equal to the product of the ratio determined in step (c) for that illumination source and magnification and the desired illumination level determined in step (d) for that magnification m.

A method of setting the illumination level of an illumination light source in an optical measurement machine having an associated zoom lens calibration file that includes at least a plurality of reference light source intensity levels for a plurality of zoom lens magnifications comprising:

• determining the ratio of illumination light source intensity level to reference light source intensity levels for at least one illumination light source at a plurality of zoom lens magnifications;
• setting the zoom lens magnification to a desired setting for making a measurement;
• and
• setting an illumination light source level to a value determined by the combination of the reference light source intensity level for the zoom lens at the desired magnification setting and the ratio at the desired zoom lens magnification.