# US 8,542,297 B2 · Method for automatically adjusting the levels of illumination sources in an optical measurement machine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,297 B2 - Document ID: US8542297B2 - Status: Granted - Kind: B2 - Application number: 13/204,097 - Filed: 2011-08-05 - Published: 2013-02-07 - Granted: 2013-09-24 - Earliest claimed: 2011-08-05 - Assignees: Quality Vision International, Inc. - Applicants: Edward T. Polidor; Daniel C. Abbas - Inventors: Edward T. Polidor; Daniel C. Abbas - Web page: https://patentgrep.com/patent/US8542297B2 ## CPC - H04N 17/002: {for television cameras} - H04N 23/74: by influencing the scene brightness using illuminating means - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A process for pre-calibrating illumination sources permits illumination light intensities to be set to a near optimal level during training of an optical inspection system. Applicants have found that the illumination source intensities for a category of illuminators are sufficiently constant from machine to machine that the data collected during calibration of an illumination source on a machine using a particular type of source may be used on other machines of the same type using the same type of illumination source when combined with the reticle light intensity data for different zoom magnification's of the particular machine being used. That is, using known data for particular machine and the illumination source light intensity data for the same type of machine and illumination source permits accurate presetting of an illumination source. ## Claims ### Claim 1 A method for pre-setting a combination of a zoom lens and an illumination source in an optical imaging system having a camera used to inspect objects at a plurality of zoom magnifications m to a near optimum setting during programming of the optical imaging system to inspect objects, comprising: determining a desired illumination level of a reference light source in combination with a zoom lens, imaging optics, and an imager in the optical imaging system at a plurality of zoom magnifications; creating and storing a calibration file of reference light source intensities for a machine M1 LRM1(m) over the plurality of zoom magnifications m, required to achieve desired measurement accuracy over an area illuminated by the reference light source where L is the normalized intensity of the reference light source, R is a value designating a reference light source, and m is a value representing the magnification of the lens; measuring illumination light source intensities for an illumination light source LI(m) required to produce a signal at the camera that is a predetermined percentage of the intensity required to produce saturation at each magnification m for which the light source I is measured; storing an array of values RI(m)=LIM1(m)/LRM1(m); and then, in a measurement step, setting the intensity of an illumination light source I for a machine M2 according to the following relationship: LIM2(m)=LRM2(m)*RI(m). ### Claim 2 (depends on 1) The method of claim 1, wherein the step of creating and storing the calibration file comprises: projecting a reticle on a calibration object; imaging the reticle with the camera; and adjusting the intensity of the reticle light source to produce optimal measurement accuracy at a plurality of zoom magnifications m at a plurality of locations on the reticle. ### Claim 3 (depends on 2) The method of claim 2 in which the reticle is projected at the best focus of the zoom lens. ### Claim 4 (depends on 2) The method of claim 2 in which the step of creating a calibration file is conducted during the manufacture of the machine. ### Claim 5 (depends on 1) The method of claim 1, wherein in RI(m)=LIM1(m)/LRM1(m), the denominator is interpolated between the stored values of LRM1(m) and wherein in LIM2(m)=LRM2(m)*RI(m), the value of LRM2(m) is interpolated between the stored values of LRM2(m). ### Claim 6 (depends on 5) The method of claim 5, wherein the interpolation comprises linear interpolation based on the square of the magnification value. ### Claim 7 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. ### Claim 8 (depends on 7) The method of claim 7 in which step (d) comprises retrieving previously determined illumination levels for a zoom lens magnification m from data associated with the second machine. ### Claim 9 (depends on 8) The method of claim 8 comprising retrieving predetermined illumination levels for zoom lens magnifications higher and lower than a desired zoom lens magnification and interpolating an illumination level for from said retrieved levels. ### Claim 10 (depends on 9) The method of claim 9 in which said interpolation comprises linear interpolation based on the square of the magnification values. ### Claim 11 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. ### Claim 12 (depends on 11) The method of claim 11 comprising interpolating the illumination light source level between two values of reference light source intensity and zoom lens magnification. ### Claim 13 (depends on 12) The method of claim 12 in which said interpolation comprises linear interpolation based on the square of the zoom lens magnification.