WAVEFRONT CURVATURE SENSOR INVOLVING TEMPORAL SAMPLING OF THE IMAGE INTENSITY DISTRIBUTION

Abstract

The present invention relates to a system and method for reconstruction of temporal wavefront changes for use in an optical system comprising: measuring the distribution function of the light intensity, e.g. the two-dimensional distribution function of the light intensity, in at least two different images taken at different times, wherein said images are taken in at least one optical plane, e.g. the same optical plane, of the optical system.

Claims

1. A method for reconstruction of temporal wavefront changes for use in an optical system, the method comprising: measuring a distribution function of light intensity in at least two different images captured at different times, wherein the at least two different images are captured in at least one optical plane.

2. The method of claim 1, further comprising: identifying at least one image of the at least two different images as an intra-time image and at least another image of the at least two different images as an extra-time image, wherein said identifying is carried out based on that the intra-time image is captured at a time before the extra-time image is captured.

3. The method of claim 2, further comprising applying a wavefront phase retrieval algorithm to the intra-time image and the extra-time image for reconstructing temporal wavefront changes that occurred between the times at which the intra-time image and the extra-time image were captured.

4. The method of claim 2, further comprising selecting or deriving the at least two different images from a series of images captured at different times.

5. The method of claim 4, wherein at least one image from the at least two different images is derived from a combination of selected images from the series of images, wherein the at least one image from the at least two different images is computationally calculated.

6. The method of claim 1, wherein the step of measuring the distribution function of the light intensity in the at least two different images captured at the different times in the at least one optical plane is carried out recurrently.

7. The method of claim 6, wherein at least one of the at least two different images remains the same during the recurrent step of measuring the distribution function of the light intensity.

8. The method of claim 1, further comprising calibrating at least one of the two different images by at least one of a phase retrieval algorithm and with data from a wavefront sensor.

9. The method of claim 1, further comprising calculating changes to be made in a deformable mirror, based on the measured distribution function of the light intensity in the at least two different images, for compensating wavefront changes that occurred between the different times at which the at least two different images were captured.

10. A system for performing reconstruction of temporal wavefront changes, comprising: at least one processor configured to measure a distribution function of light intensity in at least two different images captured at different times, wherein the at least two different images are captured in at least one optical plane.

11. (canceled)

12. The system of claim 10, further comprising at least one image detector configured to capture the at least two different images.

13. The system of claim 12, further comprising a deformable mirror configured for real-time compensation of wavefront errors or temporal wavefront changes induced by an inhomogeneous medium, wherein the processor is further configured to determine said wavefront errors or temporal wavefront changes based on data from the at least one image detector.

14. The system of claim 13, wherein the deformable mirror is further configured to induce deformations on wavefronts to generate a phase modulated signal for use in free-space optical communications.

15. The system of claim 12, wherein the at least one image detector includes at least one of: at least one indirect wavefront sensor and at least one direct wavefront sensor.

16. The system of claim 12, wherein the processor is further configured to identify at least one image of the at least two different images as an intra-time image and at least another image of the at least two different images as an extra-time image, wherein said identifying is carried out based on that the intra-time image is taken at a time before the extra-time image is taken.

17. The system of claim 16, wherein the processor is further configured to apply a wavefront phase retrieval algorithm to the intra-time image and the extra-time image for reconstructing temporal wavefront changes that occurred between the times at which the intra-time image and the extra-time image were captured.

18. The system of claim 16, wherein the processor is further configured to select or derive at least one image from the at least two different images from a combination of selected images from a series of images taken at different times, wherein the at least one image from the at least two different images is computationally calculated.

19. The system of claim 13, wherein the processor is further configured to calculate changes to be made in the deformable mirror, based on the measured distribution function of the light intensity in the at least two different images, for compensating wavefront changes that occurred between the different times at which the at least two different images were taken.

20. The method of claim 5, wherein the at least one image from the at least two different images is derived from the combination of selected images by computing an average or median of the selected images.

21. At least one computer readable storage medium including instructions stored therein that, when executed by one or more processors, causes the one or more processors to: measure a distribution function of light intensity in at least two different images captured at different times, wherein the at least two different images are captured in at least one optical plane.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0116] The following FIGURE illustrates exemplary:

[0117] FIG. 1: Exemplary optical system, exemplary Adaptive Optics (AO) system.

DETAILED DESCRIPTION

[0118] The exemplary FIG. 1 schematically shows an exemplary Adaptive Optics (AO) system 100, e.g. an AO system of a telescope, in which the above described method(s) and components can be implemented.

[0119] Herein an exemplary wavefront 102 is shown which shape has been distorted or deformed with respect to its original shape, for example, due the wavefront passing an inhomogeneous medium, e.g. a turbulent atmosphere.

[0120] The lines with arrows in the FIGURE, unless otherwise noted, exemplary represent the direction of propagation of the wavefront 102.

[0121] The wavefront 102 is received by an exemplary deformable mirror 103, that exemplary induces a wavefront phase change to the wavefront 102 and the exemplary changed wavefront 104 passes an exemplary beam splitter 106, which directs a part of the wavefront 104 to the exemplary optical system or wavefront sensor 101 which can be configured to carry out any of the above mentioned method steps for reconstructing the temporal wavefront changes of the wavefront 102, 104.

[0122] In particular, the exemplary wavefront sensor 101 may comprise at least one image detector, e.g. a common two-dimensional digital camera or a CCD sensor or a CMOS sensor.

[0123] In particular, the exemplary wavefront sensor 101 may be configured for measuring the distribution function of the light intensity, e.g. the two-dimensional distribution function of the light intensity of the wavefront 102, 104, in at least two different images taken at different times, wherein said images are taken in at least one optical plane, e.g. the same optical plane, of the wavefront sensor 101.

[0124] Furthermore, the exemplary wavefront sensor 101 may be configured to calculate the changes to be made in the deformable mirror 103 based on the measured distribution function of the light intensity in the at least two different images taken at different times, for compensating wavefront changes in the wavefront 102, 104 that occurred between the times at which said images were taken.

[0125] The exemplary wavefront sensor 101 may further be configured to forward data 110 comprising the calculated necessary changes to be made in the deformable mirror 103 to reconstruct the original wavefront shape, e.g. to compensate the distortions of the wavefront due to the inhomogeneous medium the wavefront 102, 104 has passed through.

[0126] An exemplary optional control unit 105 may receive said data 110 from the wavefront sensor 101 and may be configured to send control signals 109 to the deformable mirror 103 to control and change the shape of the deformable mirror 103, e.g. by sending control and drive signals to actuators of the deformable mirror.

[0127] A feedback loop can be realized between the wavefront sensor 101 and the deformable mirror 103 to optimize the wavefront reconstruction.

[0128] The FIGURE further exemplary shows an optional optical element 107, e.g. a lens, that can focus the wavefront 104 that has been treated/modulated/changed/corrected by the deformable mirror 103 onto a detector plane 108, e.g. the detector plane of a telescope that captures the corrected/compensated image, i.e. the output of the exemplary AO system, 100.

[0129] Followed by one sheet comprising FIG. 1, wherein the reference numerals identify the following components. [0130] 100 Exemplary Adaptive Optics (AC)) system [0131] 101 Exemplary optical system, exemplary wavefront sensor [0132] 102 Exemplary incoming wavefront, exemplary distorted wavefront [0133] 103 Exemplary deformable mirror [0134] 104 Exemplary modulation/change of incoming wavefront induced by the deformable mirror [0135] 105 Exemplary data processor/exemplary control unit to control deformable mirror, e.g. controlling the drive signals for actuators of the deformable mirror [0136] 106 Exemplary beam splitter [0137] 107 Exemplary optional optical element, e.g. lens [0138] 108 Exemplary detector plane, exemplary output image of AO system [0139] 109 Exemplary control signals to control the deformable mirror, e.g. to drive actuators of the deformable mirror [0140] 110 Exemplary control/data signals comprising the changes to be made to the deformable mirror based on the measurements of the wavefront sensor control