Apparatus and method for measuring surface topography optically

Patent metadata

Field	Value
Publication number	US-9439568-B2
Application number	US-201414323215-A
Country	US
Kind code	B2
Filing date	Jul 3, 2014
Priority date	Jul 3, 2014
Publication date	Sep 13, 2016
Grant date	Sep 13, 2016

Abstract

An apparatus is described for determining surface topography of a three-dimensional structure. The apparatus can include a probe and an illumination unit configured to output a plurality of light beams. In many embodiments, the apparatus includes a light focusing assembly. The light focusing assembly can receive and focus each of a plurality of light beams to a respective external focal point. The light focusing assembly can be configured to overlap the plurality of light beams within a focus changing assembly in order to move the external focal points along a direction of propagation of the light beams. The apparatus can include a detector having an array of sensing elements configured to measure a characteristic of each of a plurality of light beams returning from the illuminated spots and a processor coupled to the detector and configured to generate data representative of topography of the structure based on the measured characteristic.

First claim

What is claimed is:

1. An apparatus for determining surface topography of a three-dimensional structure, the apparatus comprising:
a probe sized to be inserted into an intraoral cavity of a patient;
an illumination unit configured to output a plurality of light beams;
a light focusing assembly to receive and focus each of the plurality of light beams to a respective external focal point external to the probe in order to generate illuminated spots on the structure, the light focusing assembly including one or more image space lenses and one or more object space lenses and being configured to overlap the plurality of light beams within a focus changing assembly, the focus changing assembly being located along an optical path between the one or more image space lenses and the one or more object space lenses, in order to move the external focal points along a direction of propagation of the plurality of light beams;
a detector having an array of sensing elements configured to measure a characteristic of each of a plurality of light beams returning from the illuminated spots; and
a processor coupled to the detector and configured to generate data representative of topography of the structure based on the measured characteristic of each of the plurality of light beams returning from the illuminated spots.

2. The apparatus of claim 1 , wherein at least a portion of the focus changing assembly is located at a back focal length of an objective lens of the light focusing assembly in order to inhibit changes in spacing between external focal points of the plurality of light beams when the external focal points move along the direction of propagation of the light beams.

3. The apparatus of claim 1 , wherein the focus changing assembly is located along optical paths of the plurality of light beams such that a majority of the plurality of light beams overlaps with other light beams of the plurality along at least a portion of the focus changing assembly in order to inhibit changes in spacing between external focal points of the plurality of light beams when the external focal points move along the direction of propagation of the light beams.

4. The apparatus of claim 1 , wherein each of the plurality of light beams comprises a substantially collimated configuration upon entering the focus changing assembly and wherein the focus changing assembly similarly adjusts each of the plurality of light beams to a convergent configuration, a collimated configuration, or a divergent configuration upon exiting the focus changing assembly in order to move the external focal points along the direction of propagation of the light beams.

5. The apparatus of claim 1 , wherein the characteristic comprises an intensity.

6. The apparatus of claim 1 , wherein the focus changing assembly moves the external focal points at least 10 mm.

7. The apparatus of claim 1 , wherein the one or more object space lenses comprises a telecentric lens and at least a portion of the focus changing assembly is located at a back focal length of the telecentric lens.

8. The apparatus of claim 1 , wherein the one or more image space lenses comprises a focal length and location arranged to overlap and substantially collimate the plurality of light beams passing through the focus changing assembly.

9. The apparatus of claim 1 , wherein the focus changing assembly comprises a variable optical power element operable to move the external focal points without movement of the variable optical power element.

10. The apparatus of claim 9 , wherein the variable optical power element is operable to oscillate separation between the external focal points and the probe by at least 10 mm at a frequency greater than 10 Hz.

11. The apparatus of claim 9 , wherein the variable optical power element is operable to oscillate separation between the external focal points and the probe by at least 10 mm at a frequency from approximately 50 Hz to approximately 100 Hz.

12. The apparatus of claim 1 , wherein the focus changing assembly moves the external focal points over a distance that is at least 2 times greater than a corresponding distance moved by at least a portion of the focus changing assembly and wherein the focus changing assembly comprises a focus changing group of lenses in which separation between lenses of the focus changing group of lenses is varied to move the external focal points.

13. The apparatus of claim 12 , wherein a change in separation between the lenses of the focus-changing group results in a change in separation between the external focal points and the probe of at least 5 times the change in separation between the lenses of the focus changing group of lenses.

14. The apparatus of claim 12 , wherein a change in separation between the lenses of the focus changing group results in a change in separation between the external focal points and the probe of approximately 7.5 times the change in separation between the lenses of the focus changing group of lenses.

15. The apparatus of claim 12 , wherein:
the focus changing group of lenses comprises a divergent lens and a convergent lens; and
separation between the divergent lens and the convergent lens is varied to displace the external focal points.

16. The apparatus of claim 12 , wherein the focus changing group of lenses is operable to oscillate separation between the external focal points and the probe by at least 10 mm at a frequency greater than 10 Hz.

17. The apparatus of claim 12 , wherein the focus changing group of lenses is operable to oscillate separation between the external focal points and the probe by at least 15 mm at a frequency from approximately 10 Hz to approximately 100 Hz.

18. A method of determining surface topography of a three-dimensional structure, the method comprising:
generating illuminated spots on the structure using a light focusing assembly including one or more image space lenses and one or more object space lenses to receive and focus each of a plurality of light beams to a respective external focal point external to a probe sized to be inserted into an intraoral cavity of a patient;
operating the light focusing assembly to overlap each of the plurality of light beams within a focus changing assembly located along an optical path between the one or more image space lenses and the one or more object space lenses;
operating the focus changing assembly to displace the external focal points along a direction of propagation of the plurality of light beams;
measuring a characteristic of each of a plurality of light beams returning from the illuminated spots; and
generating, with a processor, data representative of topography of the structure based on the measured characteristic.

19. An apparatus for determining surface topography of a three-dimensional structure, the apparatus comprising:
a probe sized to be inserted into an intraoral cavity of a patient;
an illumination unit configured to output a plurality of light beams to propagate toward the structure along an optical path through the probe to generate illuminated spots on the structure;
a light focusing assembly including a convergent lens and a divergent lens and operable to vary separation between the convergent lens and divergent lens to vary separation between the probe and an external focal point for each of the plurality of light beams, the light focusing assembly being configured to overlap each of the plurality of light beams toward a system aperture disposed between the light focusing assembly and a location where the plurality of light beams emanate fr

Assignees

• Align Technology Inc

Inventors

• Atiya Yossef
• Verker Tal

Classifications

• A61C1/088

  Illuminating devices or attachments (for examination of the mouth A61B1/24 and A61B1/06) · CPC title

• A61B5/0022 Primary

  Monitoring a patient using a global network, e.g. telephone networks, internet · CPC title

• A61B5/7228

  Signal modulation applied to the input signal sent to patient or subject; Demodulation to recover the physiological signal · CPC title

• A61B5/0088

  for oral or dental tissue · CPC title

• A61C9/0053

  Optical means or methods, e.g. scanning the teeth by a laser or light beam · CPC title