Method and system for inspecting beveled objects

• US 8,477,309 B2
• Filed: 08/04/2011
• Issued: 07/02/2013
• Est. Priority Date: 08/10/2010
• Status: Active Grant

• Current Assignee: Camtek Limited (Hexagon AB)
• Original Assignee: Camtek Limited (Hexagon AB)
• Inventors: Ben-Ezer, Zehava
• Primary Examiner(s): LAUCHMAN, LAYLA G
• Application Number:
  US13/197,817
• Publication Number:
  US 20120038921A1
• Time in Patent Office: 698 Days
• Field of Search: 356364-369, 356/239.1, 356/237.2, 356/239.2
• US Class Current: 356/369
• CPC Class Codes: G01N 2021/8848 Polarisation of light
• CPC Class Codes: G01N 21/87 Investigating jewels G01N21/88 takes precedence
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features
• CPC Class Codes: G01N 21/958 Inspecting transparent materials or objects, e.g. windscreens for conveyed flat sheet or rod G01N21/896

Abstract

An inspection system and a method. The method may include: illuminating the object with impinging light of a first polarization; performing a polarization based filtering of (a) multiple-reflected light signals, each multiple-reflected light signal being reflected from at least two different bevel side surfaces of the object, and (b) additional light signals, each additional light signal being reflected from a single element of the object, such as to suppress the multiple-reflected light signals, and to provide polarization based filtered light signals; and detecting the polarization based filtered light signals.

Claims

1. A method, comprising:

illuminating the object with impinging light of a first polarization;

performing a polarization based filtering of (a) multiple-reflected light signals, each multiple-reflected light signal being reflected from at least two different bevel side surfaces of the object, and (b) additional light signals, each additional light signal being reflected from a single element of the object, such as to suppress the multiple-reflected light signals, and to provide polarization based filtered light signals; and

detecting the polarization based filtered light signals.

2. The method according to claim 1, wherein the first polarization is a linear polarization along a first direction;

wherein the multiple-reflected light signals are of linear polarization along a second direction that differs from the first direction; and

wherein the additional light signals are of linear polarization along a third direction that differs from the first direction and from the second direction.

3. The method according to claim 2, wherein the performing of the polarization based filtering comprises applying a filtering function to attenuate light signals that have a polarization that differs from a linear polarization along the third direction.

4. The method according to claim 2, wherein the second direction is orthogonal to the third direction.

5. The method according to claim 1, wherein the object comprise a top surface and multiple beveled side surfaces;

wherein at least one beveled side surface has a top edge that is directed along a beveled side surface direction; and

wherein a first angle between at least one beveled side surface direction and the first direction substantially equals 45 degrees.

6. The method according to claim 1, wherein the polarization based filtering is preceded by collecting the multiple-reflected light signals and collecting the additional light signals.

7. The method according to claim 1, wherein the illuminating of the object is preceded by:

polarizing input light by a linear polarization element to provide polarized light;

directing the polarized light towards a non-polarizing beam splitter; and

directing, by the non-polarizing beam splitter, the polarized light towards the object to provide the impinging light; and

wherein the performing of the polarization based filtering is preceded by collecting the additional light signals and the collecting of the multiple-reflected light signals by passing the additional light signals and the multiple-reflected light signals through the non-polarizing beam splitter.

8. The method according to claim 6, further comprising spectral filtering at least one of the input light and the polarization based filtered light.

9. The method according to claim 1, wherein the illuminating of the object is preceded by:

directing input light towards a non-polarizing beam splitter;

directing, by the non-polarizing beam splitter, the input light towards a linear polarization element; and

polarizing the input light, by the linear polarization element to provide the impinging light;

wherein the performing a polarization based filtering is executed by the linear polarization element.

10. The method according to claim 8, wherein the linear polarization element is a closest optical element to the object.

11. The method according to claim 8, wherein at least one optical component of collection optics is positioned between the linear polarization element and the object;

wherein the collection optics is for collecting the multiple-reflected light signals and the additional light signals.

12. The method according to claim 1, comprising detecting the polarization based filtered light signals by a sensor;

and wherein the method further comprising adjusting a polarization of the polarization based filtered light to a desired polarization of the sensor.

13. The method according to claim 11, wherein the desired polarization of the sensor is a rotational polarization.

14. The method according to claim 1, wherein each beveled side surfaces has a top edge that is directed along a beveled side surface direction;

wherein each beveled side surface direction is oriented in relation to the first direction.

15. An inspection system, comprising:

optics, arranged to;

illuminate the object with impinging light of a first polarization; and

perform a polarization based filtering of (a) multiple-reflected light signals, each multiple-reflected light signal being reflected from at least two different bevel side surfaces of the object, and (b) additional light signals, each additional light signal being reflected from a single element of the object, such as to suppress the multiple-reflected light signals, and to provide polarization based filtered light signals; and

a sensor for detecting the polarization based filtered light signals.

16. The inspection system according to claim 15, wherein the first polarization is a linear polarization along a first direction;

wherein the multiple-reflected light signals are of linear polarization along a second direction that differs from the first direction; and

wherein the additional light signals are of linear polarization along a third direction that differs from the first direction and from the second direction.

17. The inspection system according to claim 16, wherein the performing of the polarization based filtering comprises applying a filtering function to attenuate light signals that have a polarization that differs from a linear polarization along the third direction.

18. The inspection system according to claim 16, wherein the second direction is orthogonal to the third direction.

19. The inspection system according to claim 16, wherein the object comprise a top surface and multiple beveled side surfaces;

wherein at least one beveled side surface has a top edge that is directed along a beveled side surface direction; and

wherein a first angle between at least one beveled side surface direction and the first direction substantially equals 45 degrees.

20. The inspection system according to claim 15, wherein the first filtering element is preceded by at least one collecting optical component for collecting the multiple-reflected light signals and collecting the additional light signals.

21. The inspection system according to claim 15, wherein the optics comprises:

a linear polarization element arranged to polarize input light to provide polarized light;

a non-polarizing beam splitter arranged to receive the polarized light from the linear polarization element and to direct the polarized light towards the object to provide the impinging light;

a first filtering element that is arranged to perform the polarization based filtering; and

a collecting optical component for collecting the multiple-reflected light signals and for collecting the additional light signals.

22. The inspection system according to claim 21, wherein the collecting optical component is positioned between the sensor and the first filtering element.

23. The inspection system according to claim 21, wherein the collecting optical component is positioned between the object and the first filtering element.

24. The inspection system according to claim 15, comprising at least one spectral filter arranged to perform spectral filtering of at least one of the input light and the polarization based filtered light.

25. The inspection system according to claim 15, comprising:

a non-polarizing beam splitter arranged to receive input light; and

a linear polarization element;

wherein the non-polarizing beam splitter is arranged to direct the input light towards the linear polarization element;

wherein the linear polarization element is arranged to polarize the input light to provide the impinging light and to perform the polarization based filtering.

26. The inspection system according to claim 25, wherein the linear polarization element is a closest optical element to the object.

27. The inspection system according to claim 25, wherein at least one optical components of the optics is positioned between the linear polarization element and the object.

28. The inspection system according to claim 15, comprising a polarization adjustment element arranged to adjust a polarization of the polarization based filtered light to a desired polarization of the sensor.

29. The inspection system according to claim 28, wherein the desired polarization of the sensor is a rotational polarization.

30. The inspection system according to claim 15, wherein each beveled side surfaces has a top edge that is directed along a beveled side surface direction;

wherein each beveled side surface direction is oriented in relation to the first direction.