Method of measuring amount of eccentricity

• US 7,792,366 B1
• Filed: 03/26/2010
• Issued: 09/07/2010
• Est. Priority Date: 03/27/2009
• Status: Expired due to Fees

• Current Assignee: Fujinon Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujinon Corporation (Fujifilm Holdings Corporation)
• Inventors: Takahashi, Kenichi, Ge, Zongtao
• Primary Examiner(s): NGUYEN, SANG H
• Application Number:
  US12/732,836
• Publication Number:
  US 20100245804A1
• Time in Patent Office: 165 Days
• Field of Search: 356389-394, 356/124, 356/124.4, 356125-127, 382/100, 382/126, 382/220, 382/286, 382/298, 399/299
• US Class Current: 382/216
• CPC Class Codes: G01B 11/272 using photoelectric detection means
• CPC Class Codes: G01M 11/0221 by determining the optical axis or position of lenses
• CPC Class Codes: G06T 2207/30108 Industrial image inspection
• CPC Class Codes: G06T 7/001 using an image reference approach

Abstract

An optical element to be measured is irradiated with the light which has passed through an indicator, thereby to form an indicator image on an image pick-up surface. Maximum peak coordinates are specified and stored as a position of the indicator image relating to the first surface. Whether the second largest peak may be specified or not is determined. In case that this result is NO, the maximum peak indicator image is deleted, and maximum peak coordinates are specified again and stored as a position of the indicator image relating to the second surface.

Claims

1. An decentration amount measuring method which sets a sample of an optical element on a mounting member which is rotatable around an axis, irradiates two-sided surfaces of the sample with a light from a light source through a measuring optical system including an indicator of a shape, leads a reflection light from the two-sided surfaces of the sample on an image forming surface, obtains a plurality of indicator images formed on an image forming surface by the reflection light, relating to the two-sided surfaces for each of at least three rotary positions on the mounting member, obtains a decentration amount of each of the two-sided surfaces on the basis of the at least three indicator image positions, and measures the decentration amount of the optical element on the basis of difference in decentration amount between the two-sided surfaces, comprising the steps:

creating a matching reference image m(x, y) which forms a reference shape of one of the plurality of indicator images when the indicator image is detected for each of the rotary positions on the mounting member;

performing matching processing between an image n(x, y) on the image forming surface and the matching reference image m (x, y);

acquiring a first indicator image having a maximum matching strength as one of the plurality of indicator images of one of the two-sided surfaces of the sample;

in case that a position of a second indicator image having a second largest matching strength is specified, acquiring the second indicator image as one of the plurality of indicator images of the other of the two-sided surfaces of the sample; and

in case that it is difficult to specify the position of the second indicator image, after deleting the first indicator image from the acquired picture image, performing matching processing between an image n′

(x, y) on the image forming surface after the deletion and the matching reference image m(x, y), and acquiring another first indicator image having a maximum matching strength at this time as one of the plurality of indicator images of the other of the two-sided surfaces of the sample.

2. The decentration amount measuring method according to claim 1, wherein the matching processing uses a phase-only correlation.