Wavefront sensor having multi-power modes, independent adjustment camera, and accommodation range measurement
View Patent ↗An improved wavefront sensor is provided that enhances the initial focus and precision of imaged spots used to determine the monochromatic wave aberrations of the eye. The wavefront sensor includes an adjustment camera that is independent of a lenslet camera. A laser in a lower power mode is projected onto the retina of the eye and is brought into more precise or sharp focus by a control system employing data from the adjustment camera, which aids in focusing the imaged spots. “Trombone”-type optics are used to adjust the focus of the light projected onto the retina and the imaged spots onto a sensor. The laser has a higher power mode used when acquiring data of the imaged spots from the sensor.
1. An improved wavefront sensor for determining wave aberrations of the eye including:
a light source that provides retinal illumination of the eye to make a wavefront measurement of the retina illumination reflected from the retina;
a lenslet array located along an optical path of the sensor for receiving the reflected retinal illumination and for creating a plurality of spot images of the reflected retinal illumination;
a detector optically engaged with the lenslet array that detects the spot images formed by the lenslet array;
a processor adapted to reeve signals from the sensor corresponding to a positional displacement of the spot images and to determine the wave aberrations from the signals, the improvement comprising:
the light source having at least a high power output and a low power output; and
an adjustment camera adapted to detect a focus of the retinal illumination on the retina from the low power output of the light source.
2. The wavefront sensor of claim 1 , further comprising a trombone reflector located along the optical path of the sensor adapted to aid in focusing the spot images on the sensor.
3. The wavefront sensor of claim 2 , wherein the trombone reflector comprises two prisms.
4. The wavefront sensor of claim 2 , wherein the trombone reflector comprises a double fold focusing trombone reflector.
5. The wavefront sensor of claim 2 , wherein the trombone reflector is adapted to aid in determining a low order aberration of the eye.
6. The wavefront sensor of claim 1 , further comprising a focus-adjusting lens system adapted to aid in focusing the spot images.
7. The wavefront sensor of claim 1 , further comprising a waveplate in the optical path of the wavefront sensor.
8. The wavefront sensor of claim 7 , wherein the waveplate is adapted to be adjusted to allow a whole image portion of the image of the reflected retinal illumination to reach the adjustment camera.
9. The wavefront sensor of claim 7 , wherein the waveplate is a λ/4 waveplate.
10. The wavefront sensor of claim 8 , wherein the waveplate is adapted to be rotated to allow a portion of the reflected retinal illumination to reach the adjustment camera.
11. The wavefront sensor of claim 1 , further comprising a polarizing beamsplitter adapted to provide a whole image portion of the reflected retinal illumination to the adjustment camera.
12. The wavefront sensor of claim 1 , wherein the adjustment camera is adapted to receive a whole image portion of the reflected retinal illumination substantially as light polarized perpendicular to the other portion of the reflected retinal illumination received by the lenslet array.
13. The wavefront sensor of claim 1 , wherein the adjustment camera is adapted to receive a whole image portion of the reflected retinal illumination substantially as light polarized parallel to the other portion of the reflected retinal illumination received by the lenslet array.
14. The wavefront sensor of claim 1 , further comprising a controllable device adapted to adjust its transmission of a whole image portion of the reflected retinal illumination received by the adjustment camera.
15. The wavefront sensor of claim 1 , further comprising a beamsplitter adapted to reflect a whole image portion of the reflected retinal illumination received by the adjustment camera.
16. The wavefront sensor of claim 1 , further comprising a laser diode oriented at an angle to the eye to aid in aligning the eye with the wavefront sensor.
17. The wavefront sensor of claim 1 , wherein the lenslet array is associated with a lenslet camera and the adjustment camera is separate from the lenslet camera.
18. The wavefront sensor of claim 1 , wherein the illumination source has at least a high power output and a low power output, further wherein the adjustment camera is adapted to detect the reflected retinal illumination from the low power output of the illumination source.
19. The wavefront sensor of claim 18 , wherein the reflected retinal illumination received by the lenslet array is produced by the high power output of the illumination source.
20. The wavefront sensor of claim 18 wherein the light source comprises a laser.
21. The wavefront sensor of claim 20 , wherein the laser emits a pulsed light that has a selectable higher output power and lower output power.
22. The wavefront sensor of claim 1 , further comprising an eye fixation target located along the optical axis of the sensor.
23. The wavefront sensor of claim 22 , wherein the fixation target comprises a picture image adapted to allow a rotational frame of reference to be defined relative to the eye.
24. The wavefront sensor of claim 22 , wherein the fixation target is adapted to allow the eye to be in a pre-determined rotational position with respect to the fixation target.
25. The wavefront sensor of claim 22 , wherein the fixation target is used to adjust the rotational position of the eye in conjunction with recognition and location of an iris of the eye.
26. The wavefront sensor of claim 1 , further comprising an eye fixation target adapted to allow the patient to fixate without accommodation.
27. The wavefront sensor of claim 1 , further comprising an eye fixation target adapted to allow the patient to focus at infinity.
28. The wavefront sensor of claim 27 , wherein the fixation target is adapted to support an accommodation-free status of the eye.
29. The wavefront sensor of claim 1 , further comprising an eye fixation target adapted to allow the patient to focus at infinity without accommodation.
30. The wavefront sensor of claim 1 , further comprising an eye fixation target adapted to allow the patient to focus at infinity with reduced accommodation.
31. The wavefront sensor of claim 1 , wherein a signal can be developed for a manual check or automatic start of patient examination from the use of the adjustment camera.
32. The wavefront sensor of claim 1 , further comprising a tuning device adapted to aid in focusing the spot images.
33. The wavefront sensor of claim 1 , wherein the reflected retinal illumination reaching said adjustment camera has an intensity that is produced by a low power output of the source and the reflected retinal illumination reaching said lenslet array has an intensity that is produced by a high power output of the source.
34. The wavefront sensor of claim 1 , wherein the retinal illumination source has at least a low power output and a high power output for detection by the adjustment camera and the lenslet array, respectively.
35. The wavefront sensor of claim 33 , wherein the low power output is on the order of the high power output divided by the number of lenslets of the lenslet array.
36. An improved method for measuring a wavefront aberration with a wavefront sensor, including the steps of:
providing a source of retinal illumination that will be the wavefront measurement light;
focusing said retinal illumination on the retina; and
directing a reflected wavefront of said retinal illumination from the retina into a lenslet array for imaging said reflected wavefront onto a detector,
the improvement characterized in that:
a) the step of providing a source of retinal illumination comprises selectively providing a high power output and a low output power of said retinal illumination;
b) providing an adjustment camera in an optical path of the wavefront sensor that can image the focus of the row illumination on the retina;
c) illuminating the retina with the low power retinal illumination and making a focus adjustment of the sensor with the aid of the adjust camera;
d) illuminating the retina with the high power retinal illumination and imaging the reflected retinal wavefront onto the detector with the lenslet array.
37. The method of claim 36 , comprising providing the adjustment camera in an optical path of the wavefront sensor that is at least in part independent of the optical path including the lenslet array.
38. The method of claim 36 , comprising providing a laser retinal illuminational source having a low power output and a high power output.
39. The method of claim 36 , comprising providing a focusing adjusting means in the optical path of the sensor.
40. The method of claim 36 , comprising linearly polarizing the high power reflected retinal wavefront light and the low power reflected retinal wavefront light.
41. The method of claim 40 , comprising linearly polarizing the high power reflected retinal wavefront light in an orientation that is parallel to the orientation of the low power reflected retinal wavefront light.
42. The method of claim 40 , comprising linearly polarizing the high power reflected retinal wavefront light in an orientation that is perpendicular to the orientation of the low power reflected retinal wavefront light.