Methods and systems for generating color images

• US 9,393,087 B2
• Filed: 08/01/2013
• Issued: 07/19/2016
• Est. Priority Date: 08/01/2013
• Status: Active Grant

• Current Assignee: Align Technology Incorporated
• Original Assignee: Align Technology Incorporated
• Inventors: Moalem, Yosi
• Primary Examiner(s): Perungavoor, Sath V
• Assistant Examiner(s): Brown, Jr., Howard D
• Application Number:
  US13/957,326
• Publication Number:
  US 20150037750A1
• Time in Patent Office: 1,083 Days
• US Class Current: 1/1
• CPC Class Codes: A61B 1/0655 Control therefor
• CPC Class Codes: A61B 1/24 for the mouth, i.e. stomatoscopes, e.g. with tongue depressors tongue depressors per se A61B13/00; Instruments for opening or keeping open the mouth combined with saliva removers A61C17/00; mouth openers for animals A61D15/00
• CPC Class Codes: A61B 5/0068 Confocal scanning
• CPC Class Codes: A61B 5/0088 for oral or dental tissue
• CPC Class Codes: A61B 5/1077 Measuring of profiles
• CPC Class Codes: A61B 5/1079 using optical or photographic means
• CPC Class Codes: A61C 1/088 Illuminating devices or attachments for examination of the mouth A61B1/24 and A61B1/06
• CPC Class Codes: A61C 9/0066 Depth determination through adaptive focusing
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures
• CPC Class Codes: G01B 2210/50 Using chromatic effects to achieve wavelength-dependent depth resolution
• CPC Class Codes: G02B 7/36 using image sharpness techniques , e.g. image processing techniques for generating autofocus signals image data processing per se G06T; in cameras having a solid state image sensor H04N23/67
• CPC Class Codes: H04N 23/56 provided with illuminating means
• CPC Class Codes: H04N 23/673 based on contrast or high frequency components of image signals, e.g. hill climbing method
• CPC Class Codes: H04N 25/134 based on three different wavelength filter elements

Abstract

Systems for generating in-focus color images are provided. Related methods and devices are also provided.

Claims

1. A system for generating a focused color image of an object, the system comprising:

a light source that produces light comprising a first wavelength and light comprising a second wavelength different from the first wavelength;

an optics system optically coupled to the light source and operable to;

focus the first wavelength to a first wavelength focal length and scan the first wavelength focal length through a plurality of different first wavelength focal lengths; and

focus the second wavelength to a second wavelength focal length and scan the second wavelength focal length through a plurality of different second wavelength focal lengths;

a detector configured to collect first wavelength image data corresponding to the first wavelength of light reflected from the object for the plurality of first wavelength focal lengths and second wavelength image data corresponding to the second wavelength of light reflected from the object for the plurality of second wavelength focal lengths; and

a processor configured to, for each of a plurality of different locations in the focused color image;

select one of the first wavelength focal lengths for which the first wavelength is focused relative to the object at the respective location;

select one of the second wavelength focal lengths for which the second wavelength is focused relative to the object at the respective location; and

combine the first wavelength image data corresponding to the selected first wavelength focal length for the respective location and the second wavelength image data corresponding to the selected second wavelength focal length for the respective location, thereby generating focused color image data for the respective image location for the focused color image of the object.

2. The system of claim 1, wherein the optics system comprises a movable optical component configured to:

scan the first wavelength focal length through the plurality of first wavelength focal lengths; and

scan the second wavelength focal length through the plurality of second wavelength focal lengths.

3. The system of claim 1, wherein:

the light source produces light comprising a third wavelength different from the first and second wavelengths;

the optics system is operable to focus the third wavelength to a third wavelength focal length and scan the third wavelength focal length through a plurality of different third wavelength focal lengths;

the detector is configured to collect third wavelength image data corresponding to the third wavelength of light reflected from the object for the plurality of third wavelength focal lengths; and

the processor is configured to, for each of the plurality of different locations in the focused color image;

select one of the third wavelength focal lengths for which the third wavelength is focused relative to the object at the respective location; and

combine the first wavelength image data corresponding to the selected first wavelength focal length for the respective location, the second wavelength image data corresponding to the selected second wavelength focal length for the respective location, and the third wavelength data corresponding to the selected third wavelength focal length for the respective location;

thereby generating the focused color image data for the respective image location for the focused color image of the object.

4. The system of claim 3, wherein at least one of the first wavelength image data, the second wavelength image data, and the third wavelength image data comprises intensity data for the respective wavelength for each of the plurality of the respective at least one wavelength focal lengths.

5. The system of claim 4, wherein:

the first wavelength is a red light wavelength;

the second wavelength is a green light wavelength; and

the third wavelength is a blue light wavelength.

6. The system of claim 4, wherein the respective at least one wavelength image data includes position data corresponding to a plurality of pixels in the detector.

7. The system of claim 1, wherein:

the light source comprises a white light source; and

the detector comprises a color image detector.

8. The system of claim 1, wherein at least one of the selected first wavelength focal lengths and the selected second wavelength focal lengths, for the plurality of different locations in the focused color image, comprise at least two different focal lengths.

9. The system of claim 1, further comprising a scanning system configured to collect surface topology data of the object.

10. The system of claim 9, wherein:

the scanning system comprises a monochromatic light source used to illuminate the object with monochromatic light;

a focal length of the monochromatic light is scanned through a plurality of different monochromatic light focal lengths;

for each of a plurality of different locations in the focused color image, one of the monochromatic light focal lengths is selected, for which the monochromatic light is focused relative to the object at the respective location, based on analysis of the monochromatic light reflected from the object at the respective location; and

the surface topology data is generated based on the selected monochromatic light focal lengths.

11. The system of claim 10, wherein the surface topology data and the focused color image of the object are aligned in a common frame reference.

12. The system of claim 1, wherein the system is wholly or partially incorporated into a hand-held device.

13. The system of claim 1, wherein the light source produces light that simultaneously comprises the first and second wavelengths.

14. The system of claim 1, wherein the selected focal length for each respective wavelength being focused relative to the object results in a blur circle diameter not greater than 0.4 mm.

15. The system of claim 14, wherein the selected focal length for each respective wavelength being focused relative to the object results in a blur circle diameter not greater than 0.2 mm.

16. The system of claim 1, wherein the selection of the first and second wavelength focal lengths is based on at least one of:

(a) intensity of light reflected from the object, and (b) spatial frequency contents of an image portion of at least one of the first and second wavelengths reflected from the object.

17. A computer-implemented method for generating a focused color image of an object, the method comprising:

processing image signals corresponding to a first wavelength of light of a plurality of different focal lengths that is reflected from the object so as to generate first wavelength image data;

processing image signals corresponding to a second wavelength of light of a plurality of different focal lengths that is reflected from the object so as to generate second wavelength image data, the second wavelength being different from the first wavelength; and

for each of a plurality of different locations in the focused color image;

selecting one of the first wavelength focal lengths for which the first wavelength is focused relative to the object at the respective location;

selecting one of the second wavelength focal lengths for which the second wavelength is focused relative to the object at the respective location; and

combining the first wavelength image data corresponding to the selected first wavelength focal length for the respective location and the second wavelength image data corresponding to the selected second wavelength focal length for the respective location, thereby generating focused color image data for the respective image location for the focused color image of the object.

18. The method of claim 17, further comprising:

processing image signals corresponding to a third wavelength of light reflected from the object for a plurality of different focal lengths used to illuminate the object with light that includes the third wavelength so as to generate third wavelength image data, the third wavelength being different from the first wavelength and the second wavelength; and

for each of the plurality of different locations in the focused color image;

selecting one of the third wavelength focal lengths for which the third wavelength is focused relative to the object at the respective location; and

combining the first wavelength image data corresponding to the selected first wavelength focal length for the respective location, the second wavelength image data corresponding to the selected second wavelength focal length for the respective location, and the third wavelength data corresponding to the selected third wavelength focal length for the respective location;

thereby generating the focused color image data for the respective image location for the focused color image of the object.

19. The method of claim 18, wherein the first wavelength of light comprises a wavelength between about 465 nm and about 485 nm, the second wavelength of light comprises a wavelength between about 500 nm and about 520 nm, the third wavelength of light comprises a wavelength between about 640 nm and about 660 nm, or a combination thereof.

20. The method of claim 18, wherein at least one of the first wavelength image data, the second wavelength image data, and the third wavelength image data comprises intensity data for the respective wavelength for each of the plurality of the respective at least one wavelength focal lengths.

21. The method of claim 17, wherein the image signals are generated in response to reflections from the object produced via white light illumination of the object.

22. The method of claim 17, further comprising processing image signals to generate surface topology data of the object.

23. The method of claim 22, wherein the imaging signals processed to generate the surface topology data are generated in response to reflections from the object of monochromatic light that is scanned through a plurality of different focal lengths, the method further comprising:

for each of a plurality of different locations in the focused color image, selecting one of the monochromatic light focal lengths, for which the monochromatic light is focused relative to the object at the respective location, based on analysis of the monochromatic light reflected from the object at the respective location; and

generating the surface topology data based on the selected monochromatic light focal lengths.

24. The method of claim 23, wherein the surface topology data and the focused color image of the object are aligned in a common frame of reference.

25. The method of claim 17, wherein the selected focal length for each respective wavelength being focused relative to the object results in a blur circle diameter not greater than 0.4 mm.

26. The method of claim 25, wherein the selected focal length for each respective wavelength being focused relative to the object results in a blur circle diameter not greater than 0.2 mm.

27. The method of claim 17, wherein the selection of the first and second wavelength focal lengths is based on at least one of:

(a) intensity of light reflected from the object, and (b) spatial frequency contents of an image portion of at least one of the first and second wavelengths reflected from the object.

28. A system for generating a focused color image of an object in low-light conditions, the system comprising:

a color detector comprising a two-dimensional pixel array that includes;

(a) a plurality of red pixels distributed within the pixel array, (b) a plurality of green pixels distributed within the pixel array, and (c) a plurality of blue pixels distributed within the pixel array;

wherein each of the red pixels is configured to detect a red wavelength of light reflected from the object, each of the green pixels is configured to detect a green wavelength of light reflected from the object, and each of the blue pixels is configured to detect a blue wavelength of light reflected from the object, and wherein the number of red pixels is greater than the number of green pixels, and the number of red pixels is greater than the number of blue pixels;

and a processor configured to process signals received from the red pixels, the green pixels, and the blue pixels to;

generate red wavelength image data corresponding to the red wavelength of light reflected from the object for a plurality of red wavelength focal lengths;

generate green wavelength image data corresponding to the green wavelength of light reflected from the object for a plurality of green wavelength focal lengths;

generate blue wavelength image data corresponding to the blue wavelength of light reflected from the object for a plurality of blue wavelength focal lengths;

for each of a plurality of different locations in the focused color image;

select one of the red wavelength focal lengths for which the red wavelength is relative to the object at the respective location, wherein the selected red wavelength focal lengths for the plurality of different locations in the focused color image comprise at least two different focal lengths;

select one of the green wavelength focal lengths for which the green wavelength is focused relative to the object at the respective location, wherein the selected green wavelength focal lengths for the plurality of different locations in the focused color image comprise at least two different focal lengths;

select one of the blue wavelength focal lengths for which the blue wavelength is focused relative to the object at the respective location, wherein the selected blue wavelength focal lengths for the plurality of different locations in the focused color image comprise at least two different focal lengths;

and combining the red wavelength image data corresponding to the selected red wavelength focal length for the respective location, the green wavelength image data corresponding to the selected green wavelength focal length for the respective location, and the blue wavelength data corresponding to the selected blue wavelength focal length for the respective location, thereby generating the focused color image data for the respective image location for the focused color image of the object.

29. The system of claim 28, wherein the processor is configured to process signals from the color detector to generate surface topology data for the object, the system further comprising an optics system, the optics system and the color detector being configured to couple an array of confocal beams used to generate the surface topology for the object with an array of the red pixels such that each confocal beam illuminates a corresponding red pixel in the array of red pixels.

30. The system of claim 28, wherein the selected focal length for each respective wavelength being focused relative to the object results in a blur circle diameter not greater than 0.4 mm.

31. The system of claim 30, wherein the selected focal length for each respective wavelength being focused relative to the object results in a blur circle diameter not greater than 0.2 mm.

32. The system of claim 28, wherein the selection of the red, green, and blue wavelength focal lengths is based on at least one of:

(a) intensity of light reflected from the object, and (b) spatial frequency contents of an image portion of at least one of the red, green, or blue wavelengths reflected from the object.

33. The system of claim 28, wherein the system is configured to image an oral cavity of a patient.