Step difference detection apparatus and processing apparatus using the same

• US 6,421,451 B2
• Filed: 09/11/1998
• Issued: 07/16/2002
• Est. Priority Date: 09/16/1997
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Shimura, Kei, Saito, Tutomu, Honguh, Yoshinori, Shiratsuchi, Masataka
• Primary Examiner(s): Boudreau, Leo
• Assistant Examiner(s): Choobin, M B
• Application Number:
  US09/152,061
• Publication Number:
  US 20010055409A1
• Time in Patent Office: 1,404 Days
• Field of Search: 382/101, 382/100, 382/112, 382/154, 209/584, 209/900, 705/401, 356/613, 250/559.44
• US Class Current: 382/101
• CPC Class Codes: G06V 10/145 Illumination specially adapted for pattern recognition, e.g. using gratings

Abstract

The present invention provides a step difference detection apparatus including an illumination section for emitting illumination light, an incident section for making the illumination light emitted by the illumination section be incident on a plurality of small illumination regions on an object carried in a predetermined carrier direction from different directions, an image sensing section for inputting an image of the regions on the object illuminated with the illumination light which is made to be incident by the incident section, and a detection section for detecting a step difference on the object on the basis of the image sensed by the image sensing section.

Claims

1. A detection apparatus comprising:

an illumination device configured to illuminate a region of an object with a plurality of types of illumination light beams, each of said illumination light beams being incident on said region from different respective directions and having different respective characteristics;

a beam splitting device configured to split a light beam reflected from the region into a plurality of light components in units of types of the illumination light beams using the respective different characteristics of the plurality of types of illumination light beams;

image sensing devices configured to receive the plurality of light components split by said beam splitting device to input a plurality of images corresponding to the plurality of types of illumination light beams, respectively; and

an image processing device configured to process the plurality of images input by said image sensing devices to detect a step change in surface elevation at the region.

2. The apparatus according to claim 1, wherein

the plurality of types of illumination light beams having different characteristics are two types of light beams having different spectral characteristics.

3. The apparatus according to claim 1, wherein

the plurality of types of illumination light beams having different characteristics are two types of light beams having different polarization characteristics.

4. The apparatus according to claim 2, wherein

the two types of light beams having different spectral characteristics have wavelengths not less than 600 nm as major components.

5. The apparatus according to claim 2, wherein

a value obtained by dividing a difference between wavelengths of the two types of light beams having different spectral characteristics by an average value of the wavelengths is not less than {fraction (1/40)}.

6. The apparatus according to claim 1, wherein said image processing device comprises a difference calculation device configured to determine a difference between the plurality of images input by said image sensing devices.

7. The apparatus according to claim 1, wherein

said beam splitting section comprises a dichroic mirror.

8. The apparatus according to claim 1, wherein the plurality of types of illumination light beams are obtained from one light source.

9. The apparatus according to claim 1, further comprising:

means for processing for the object on the basis of the step change in surface elevation at the region detected by said image processing device.

10. A detection apparatus comprising:

an illumination device configured to illuminate a linear region of an object carried in a predetermined carrying direction with a plurality of types of illumination light beams, each of said illumination light beams being incident on said linear region from different respective directions and having different respective characteristics, wherein the linear region extends in a direction crossing a predetermined carrying direction and the plurality of types of illumination light beams incident on said linear region from different respective directions to form shadows on the object extending in a direction crossing the carrying direction;

a beam splitting device configured to split a light beam reflected from the linear region into a plurality of light components using the respective different characteristics of the plurality of types of illumination light beams;

image sensing devices configured to receive the plurality of light components split by said beam splitting device to input a plurality of images corresponding to the plurality of types of illumination light beams, respectively; and

a detection device configured to detect a step change in surface elevation at the linear region on the basis of the image input by said image sensor.

11. A detection apparatus comprising:

an illumination means for emitting illumination light;

a means for receiving the illumination light from said illumination means for forming object light beams therefrom that are incident onto a plurality of small illumination regions on an object surface from different illumination directions;

a moving means for moving the object surface in a predetermined direction;

an image sensing means receiving the object light beams from said plurality of small illumination regions and to providing an output indicative thereof; and

a detection means for detecting a step change in surface elevation at the plurality of small illumination regions on the basis of the output received from the image sensing means.

12. A detection apparatus comprising:

an illumination means for illuminating a region of an object with a plurality of types of illumination light beams, each of said illumination light beams being incident on said region from different respective directions and having different respective characteristics;

a beam splitting means for splitting a light beam reflected from the region into a plurality of light components in units of types of the illumination light beams using the respective different characteristics of the plurality of types of illumination light beams;

an image sensing means receiving the plurality of light components split by said beam splitting means and inputting a plurality of images corresponding to the plurality of types of illumination light beams, respectively; and

an image processing means for processing the plurality of images input by said image sensing means for detecting a step change in surface elevation at the region.

13. A detection apparatus comprising:

an illumination means for illuminating a linear region of an object with a plurality of types of illumination light beams, each of said illumination light beams being incident on said linear region from different respective directions and having different respective characteristics, wherein the object is moved in a predetermined carrying direction by a moving means and the linear region extends in a direction crossing the predetermined carrying direction and the plurality of types of illumination light beams incident on said linear region from different respective directions form shadows on the object extending in a direction crossing the carrying direction;

a beam splitting means for splitting a light beam reflected from the linear region into a plurality of light components using the respective different characteristics of the plurality of types of illumination light beams;

an image sensing means receiving the plurality of light components split by said beam splitting means and inputting a plurality of images corresponding to the plurality of types of illumination light beams, respectively; and

a detection means for detecting a step change in surface elevation at the linear region on the basis of the image input by said image sensing means.

14. A step difference detection apparatus comprising:

an illumination device configured to emit an illumination light;

an incident device configured to receive the illumination light from said illumination device and to form object light beams therefrom onto a plurality of small illumination regions on an object surface, wherein the object light beams illuminate the plurality of small illumination regions adjacent to each other from different directions, respectively;

an image sensing device configured to receive the object light beams from said plurality of small illumination regions and to provide an output indicative thereof; and

a detection device configured to detect a step change in surface elevation at the plurality of small illumination regions based on the output received from the image sensing device.

15. The apparatus according to claim 14, wherein said incident device is configured to form the object light beams so that the object light beams illuminate a linear region including the plurality of small illumination regions.

16. The apparatus according to claim 15, wherein the different directions of the object light beams include first and second directions alternately changing in units of the adjacent small illumination regions.

17. The apparatus according to claim 14, wherein the image sensing device comprises an area sensor configured to sense a two-dimensional region at once.

18. The apparatus according to claim 14, further comprising a device configured to execute processing for the object based on the step change in surface elevation at the plurality of small illumination regions detected by the detection device.

19. The apparatus according to claim 14, wherein

said illumination device comprises two illumination units configured to emit two illumination light beams from two illumination directions, respectively, as said illumination light,

said incident device includes two slits inserted between each of respective ones of said two illumination units and the plurality of small illumination regions.

20. The apparatus according to claim 19, wherein each of the two slits, with d being a distance value measured along an optical path extending between each of the two slits and the plurality of small regions, comprises at least one light-emitting portion having a width dimension of a value p and configured to transmit a respective beam portion of one of the illumination light beams emitted from a respective one of said two slits to form each of said object light beams with a predetermined value of illuminance corresponding to {square root over (e)} of an illuminance at a central point on a plane separated from one point of said illumination device by a unit distance, with e being a base of natural logarithm, and a radius value w, and at least one light shielding portion having a width dimension of the value p and configured to shield a respective beam portion of one of the two illumination light beams, and

the width dimension value p divided by the product of the radius value w and the path length distance value d has a value greater than 4.

21. The apparatus according to claim 19, wherein each of the two slits, with d being a distance value measured along an optical path extending between each of the two slits and the plurality of small regions, comprises at least one light-emitting portion having a width dimension of a value p and configured to transmit a respective beam portion of one of the illumination light beams emitted from a respective one of said two slits to from each of said object light beams with a predetermined value of illuminance corresponding to {square root over (e)} of an illuminance at a central paint on a plane separated from one point of said illumination device by a unit distance, with e being a base of natural logarithm, and a radius value w, and at least one light shielding portion having a width dimension of the value p and configured to shield a respective beam portion of one of the two illumination light beam, and the width dimension value p divided by the product of the radius Value w and the path length distance value d has a value greater than 8.

22. The apparatus according to claim 20, wherein each of said slits comprises a transparent member having a pattern configured to provide a plurality of transmitting portions and shielding portions.

23. The apparatus according to claim 21, wherein each of said slits comprises a transparent member having a pattern configured to provide a plurality of transmitting portions and shielding portions.

24. A step difference detection apparatus comprising:

an illumination device configured to form two object light beams onto a linear region on a surface of the object, wherein the linear region is alternately illuminated by the two object light beams from different directions at a predetermined timing;

an image sensing device configured to receive the two object light beams reflected from said linear region and to provide an output indicative thereof; and

a detection device configured to detect a step change in surface elevation at the linear region based on the output received from the image sensing device.