US 6,861,659 B2Granted

Method of inspecting ununiformity of transparent material, apparatus therefor, and method of selecting transparent substrate

AssigneeHoya Corporation

InventorMasaru Tanabe

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Abstract

A laser beam L from a laser 2 is introduced from an introducing surface into a transparent substrate 1 by using mirrors 31 and 32. The laser beam introduced through the transparent substrate 1 repeats a total reflection on the surfaces (main surfaces and end surfaces) of the transparent substrate 1 and enters a state in which the laser beam is almost confined in the substrate 1. When an ununiform portion such as a scratch exists on the surface of the transparent substrate 1, however, total reflecting conditions are not satisfied and the light leaks out of the ununiform portion. The leaked light is formed as an image on a CCD 6 by a lens system 7 and an image process is executed by an image processing apparatus 12. In a detected image, the ununiform portion in which the scratch or the like exists is brightly seen in a linear or a dot form in a black background, so that the ununiform portion such as a very fine scratch can be detected.

Claims10

Dependent claims

A method for inspecting an ununiformity of a transparent material by introducing a laser beam therein;

wherein said transparent material comprises at least one pair of total reflective surfaces arranged so as to face each other in such a manner that the laser beam propagates along said pair of total reflective surfaces with being repeatedly and totally reflected therebetween, at least one pair of turning surfaces arranges so as to face each other in such a manner that the laser beam is turned back when the laser beam is impinged thereagainst, and an introductory surface for introducing the laser beam into said transparent material disposed in a manner to be sandwiched therebetween by at least one of said total reflective surfaces and at least one of said turning surfaces;
said total reflective surfaces, said turning surfaces and said introductory surface being mirror-polished;
and wherein when an optical path in said transparent material is uniform, the laser beam is introduced in such a manner that the laser beam which propagates in the transparent material and impinged on said total reflective surfaces and said turning surfaces totally reflects, and in an inspecting region of the transparent material sandwiched by one certain pair of said total reflective surfaces and one certain pair of said turning surfaces, one certain plane in said inspecting region filled with the laser beam by propagating the laser beam in said transparent material is relatively moved in the direction in which the inspecting region is filled with the laser beam for said transparent material;
and
when an ununiform portion exists in the optical path of the laser beam which is introduced and propagated in said transparent material, light which leaks out of said total reflective surface and/or said returning surfaces is detected, thereby inspecting the ununiformity of the transparent material.

2 more elements

A method for inspecting an ununiformity of a transparent material by introducing a laser beam therein;

wherein said transparent material comprises at least one pair of total reflective surfaces so as to face each other in such a manner that the laser beam propagates along said pair of total reflective surfaces with being repeatedly and totally reflected therebetween, at least one pair of turning surfaces arranged so as to face each other in such a manner that the laser beam is turned back when the laser beam is impinged thereagainst, and an introductory surface for introducing the laser beam into said transparent material disposed in a manner to be sandwiched therebetween by at least one of said total reflective surfaces and at least one of said turning surfaces;
said total reflective surfaces, said turning surfaces and said introductory surface being mirror-polished;
and wherein when an optical path is said transparent material is uniform, the laser beam is introduced through a chamfer surface by changing an incident angle thereof within a range where the laser beam totally reflects on said total reflective surfaces and said turning surfaces and repeats between at least one pair of end surfaces in such a manner that the laser beam which propagates in the transparent material and impinges on said total reflective surfaces and said turning surfaces totally reflects, and the laser beam is propagated so as to repeat between at least one pair of said turning surfaces and the laser beam is spread in an inspecting region which is formed by the propagation and is surrounded by said total reflective surfaces and said turning surfaces;
and
when an ununiform portion exists in the optical path of the laser beam which is introduced and propagate in said transparent material, light which leaks out of said total reflective surface and/or said returning surfaces is detected, thereby inspecting the ununiformity of the transparent material.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/421,431Filed 23 Apr 2003 · continuation
Priority: JP 9-19276317 Jul 1997
Published: US 2003/0218145 A127 Nov 2003
Granted: 1 Mar 2005
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

G01N 21/958
Characterised by the material or shape of the object to be examined: inspecting transparent materials or objects, e.g. windscreens
G01N 21/552
Specular reflectivity: attenuated total reflection
G01N 2021/8965
Optical defects in or on transparent materials, e.g. distortion, surface flaws in conveyed flat sheet or rod: using slant illumination, using…
G01N
Investigating or analysing materials by determining their chemical or physical properties

Family

PCTJP98/03200Parent of this continuation · filed 16 Jul 1997
US 6,610,994 B1Parent of this continuation · filed 26 Aug 2003
US 2003/0218145 A1Pre-grant publication · published 27 Nov 2003
Application09/254,849Parent of this continuation
US 6,861,659 B2This patent

From the US filing history. Foreign family members aren’t listed.