Methods and systems for generating color images

• US 9,956,061 B2
• Filed: 06/07/2016
• Issued: 05/01/2018
• 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:
  US15/175,311
• Publication Number:
  US 20160354184A1
• Time in Patent Office: 693 Days
• 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 focused color image data, the system comprising:

a light source that produces light comprising a plurality of wavelengths;

an optics system optically coupled to the light source and operable to focus each of the plurality of wavelengths to a corresponding plurality of respective focal lengths;

a detector configured to collect image data for each of the plurality of wavelengths at each corresponding plurality of respective focal lengths; and

a processor configured to, for an image location in the image data;

determine, for each of the plurality of wavelengths, a focal length of the corresponding plurality of respective focal lengths for which the respective wavelength is focused relative to the object at the image location; and

combine the image data for each of the plurality of wavelengths at the determined respective focal lengths, thereby generating focused color image data for the image location.

2. The system of claim 1, wherein the optics system comprises a movable optical component configured to, for each of the plurality of wavelengths, scan through the corresponding plurality of respective focal lengths.

3. The system of claim 1, wherein the plurality of wavelengths comprises at least three wavelengths.

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

5. The system of claim 4, wherein the plurality of wavelengths comprise a red light wavelength, a green light wavelength;

and a blue light wavelength.

6. The system of claim 4, wherein the 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 the processor is configured to generate focused color image data for a plurality of image locations, and wherein at least one of the plurality of wavelengths has different determined respective focal lengths for at least two of the plurality of image locations.

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 each of the plurality of wavelengths.

14. The system of claim 1, wherein the determined focal length for a wavelength of the plurality of wavelengths 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 determined focal length for a wavelength of the plurality of wavelengths 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 determination of each of the plurality of respective wavelength focal lengths is based on:

intensity of light reflected from the object,

spatial frequency contents of an image portion of at least one of the plurality of wavelengths reflected from the object, or

a combination thereof.

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

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

for a location in the image data;

determining, for each of the plurality of wavelengths, a focal length of the corresponding plurality of respective focal lengths for which the respective wavelength is focused relative to the object at the image location; and

combining the image data for each of the plurality of wavelengths at the determined respective focal lengths, thereby generating focused color image data for the image location.

18. The method of claim 17, wherein the plurality of wavelengths comprises at least three wavelengths.

19. The method of claim 18, wherein the at least three wavelengths comprise a wavelength between about 465 nm and about 485 nm, a wavelength between about 500 nm and about 520 nm, and a wavelength between about 640 nm and about 660 nm.

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

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 determined focal length for a wavelength of the plurality of wavelengths 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 determined focal length for a wavelength of the plurality of wavelengths 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 computer-implemented method for generating a focused color image of an object in low-light conditions, the method comprising:

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

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

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

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

selecting a red focal length of the plurality of red wavelength focal lengths for which the red wavelength is focused relative to the object at the respective location;

selecting a green focal length of the plurality of green wavelength focal lengths for which the green wavelength is focused relative to the object at the respective location;

selecting a blue focal length of the plurality of blue wavelength focal lengths for which the blue wavelength is focused relative to the object at the respective location; 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 method of claim 28, further comprising generating surface topology data by processing data from an array of confocal beams.

30. The method 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 method 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.