Optical system for generating a pattern which changes over time for a confocal microscope

Patent metadata

Field	Value
Publication number	US-9910255-B2
Application number	US-201415021588-A
Country	US
Kind code	B2
Filing date	Sep 11, 2014
Priority date	Sep 11, 2013
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

The invention relates to an optical system for generating a pattern which changes over time for a confocal microscope. The system includes a light source arrangement, a beam splitter, and a lens arrangement. The beam splitter allows for passage of a light beam proceeding from the light source arrangement in the direction of an object and for deflecting the reflected light beam, reflected by the object in a focal plane, in the direction of a detector. The detector includes a detector pattern for detecting an image of the object. The lens arrangement is between the beam splitter and the object and includes: a light source that generates the light beam, and a device configured to switch a direction of polarization of the light beam to generate a changing projector pattern.

First claim

The invention claimed is:

1. An optical system for generating a pattern that changes over time for a confocal microscope, the optical system comprising:
a light source arrangement from which a light beam travels to an object that reflects the light beam to generate a reflected light beam;
a beam splitter for allowing passage of the light beam proceeding from the light source arrangement in the direction of the object and for deflecting the reflected light beam, reflected by the object in a focal plane, in the direction of a detector, wherein the detector includes a detector pattern for detecting an image of the object; and
a lens arrangement between the beam splitter and the object,
wherein the light source arrangement includes:
a light source that generates the light beam, and
a device configured to switch a direction of polarization of the light beam to generate a changing projector pattern.

2. The optical system according to claim 1 , wherein the device is fixedly downstream and is a controllable optical retarder.

3. The optical system according to claim 2 , wherein the controllable optical retarder is a Pockels cell configured to rotate a direction of polarization from entrance to exit depending on a voltage applied to electric terminals of the Pockels cell,
wherein the Pockels cell is configured such that changing the voltage applied to the electric terminals from a first voltage to a second voltage changes a retardation by lambda/2 or an odd multiple thereof.

4. The optical system according to claim 2 , wherein the controllable optical retarder is a stationary rotating lambda/4 retarder.

5. The optical system according to claim 1 , wherein the light source is a laser diode that emits polarized light or an LED having a downstream polarizer.

6. The optical system according to claim 1 , wherein the projector pattern is a line pattern or a checkerboard pattern.

7. The optical system according to claim 1 , further comprising:
means for aligning the projector pattern and the detector pattern.

8. The optical system according to claim 1 , further comprising:
a transparent LCD configured to generate the projector pattern.

9. The optical system according to claim 1 , wherein a filter is provided as a means for evaluating received signals, and
wherein a switching frequency of the filter is synchronized with a switching frequency for a polarization direction of the light source.

10. The optical system according to claim 9 , wherein the filter is a lock-in amplifier.

11. A method for scanning a surface of an object using the optical system according to any of claims 1 - 4 , 5 , and 6 - 10 , the method comprising the steps of:
aligning the projector pattern and the detector pattern;
tuning the focal plane during a change of the proj ector pattern with a high switching frequency;
receiving a signal having a frequency corresponding to the switching frequency;
narrow-band filtering of the received signal and searching for a maximum intensity of the signal after the narrow band filtering; and
searching for a signal peak of constant width.

12. An optical system for generating a pattern that changes over time for a confocal microscope, the optical system comprising:
a light source arrangement configured to emit a light beam,
wherein the light source arrangement includes a first light source and a second light source,
wherein a polarization direction of light emitted from the first light source is rotated 90° with respect to a polarization direction of light emitted from the second light source, and
wherein a light path of the first light source and a light path of the second light source are combined into an optical beam path within the light source arrangement;

a beam splitter for allowing passage of the light beam emitted from the light source arrangement in a direction of an object and for deflecting a reflected light beam, reflected by the object in a focal plane, in the direction of a detector,
wherein the detector includes a detector pattern for detecting an image of the object; and
a lens arrangement between the beam splitter and the object,
wherein the light source arrangement includes a switching device configured to switch a polarization of the light beam emitted from the light source arrangement by alternately switching the first light source and the second light source to a switched-on state such that only one of the first light source and the second light source is in a switched-on state at a time.

13. The optical system according to claim 12 , wherein the first light source and the second light source are arranged side by side.

14. The optical system according to claim 13 , further comprising:
a diffusion disk downstream of the first light source and the second light source.

15. The optical system according to claim 13 , further comprising:
a beam combiner,
wherein the first light source and the second light source are arranged offset by 90° , and the beam combiner is arranged to combine the light path of the first light source and the light path of the second light source into the optical beam path combining their light paths into the single light path.

16. The optical system according to claim 12 , wherein the light emitted from the first light source and the light emitted from the second light source are linearly polarized.

17. The optical system according to claim 16 , further comprising:
wherein a lambda/4 retarder is arranged downstream from the light source arrangement and configured to convert the polarization directions into two circular polarization directions, one counterclockwise and one clockwise.

18. The optical system according to claim 17 , further comprising:
a linear polarizer configured to block light from positions at which the polarization is rotated 90° , and allow light to pass through from positions at which the polarization direction is present so that the projector pattern is transparent at these positions,
wherein the linear polarizer is arranged between a structured retarder of the lambda/4 retarder and the lens arrangement.

Assignees

• Sirona Dental Systems Gmbh
• Dentsply Sirona Inc

Inventors

• Berner Markus

Classifications

• G02F1/0136

  for the control of polarisation, e.g. state of polarisation [SOP] control, polarisation scrambling, TE-TM mode conversion or separation (G02F1/0353 takes precedence) · CPC title

• A61B5/1077

  Measuring of profiles · CPC title

• A61B5/0066

  Optical coherence imaging · CPC title

• G02B21/0032 Primary

  Optical details of illumination, e.g. light-sources, pinholes, beam splitters, slits, fibers (G02B21/0036 - G02B21/008; means for illumination of specimens in general G02B21/06) · CPC title

• G02B27/10

  Beam splitting or combining systems (polarising systems G02B27/28; mixing and splitting light signals using optical waveguides G02B6/28; {beam shaping, e.g. changing the cross-sectional area, by dividing or superposing multiple light beams G02B27/0905}) · CPC title