Wavefront sensor
View Patent ↗The present invention relates to a wavefront sensor using a pair of screens, each having a two-dimensional array of circular apertures, to achieve Moiré effects, and its use to measure the slope of a wavefront.
1. An apparatus comprising:
a) a first screen comprising a first two-dimensional array of spaced circular apertures, wherein the first screen is placed downstream of a light source;
b) a second screen comprising a second two-dimensional array of spaced circular apertures, wherein the second screen is placed downstream of the first screen, the second screen is in a plane parallel to the first screen, and the second screen is rotated relative to the first screen; and
c) a light detector downstream of the second screen.
2. The apparatus of claim 1 , wherein the first two-dimensional array and the second two-dimensional array are identical.
3. The apparatus of claim 1 , wherein at least one screen is a Hartmann screen.
4. The apparatus of claim 3 , wherein the first screen and the second screen are Hartmann screens.
5. The apparatus of claim 1 , wherein at least one spaced circular aperture of the first screen or second screen includes a lenslet.
6. The apparatus of claim 5 , wherein each of the spaced Circular apertures of the first screen and the second screen includes a lenslet.
7. The apparatus of claim 1 , wherein the second screen is rotated about 1 to about 30 degrees relative to the first screen.
8. The apparatus of claim 1 , further comprising a lens.
9. The apparatus of claim 8 , wherein the lens is placed between the second screen and the light detector.
10. The apparatus of claim 8 , wherein the lens is placed upstream of the first screen.
11. The apparatus of claim 1 , further comprising a beam splitter positioned upstream of the first screen.
12. The apparatus of claim 1 , wherein at least one of the first and second screens is substantially opaque in the area surrounding the circular apertures.
13. The apparatus of claim 1 , wherein the circular apertures of at least one of the first screen and the second screen are spaced apart by about 0.0002 inch to about 0.02 inch.
14. A method of measuring characteristics of a lens comprising:
a) directing light from a light source into the lens;
b) directing the light from the lens through a first screen comprising a first two-dimensional array of spaced circular apertures;
c) directing the light from the first screen through a second screen comprising a second two-dimensional array of spaced circular apertures, wherein the second screen is placed downstream of the first screen, the second screen is in a plane parallel to the first screen, and the second screen is rotated relative to the first screen;
d) detecting the light from the second screen at a light detector.
15. The method of claim 14 , wherein the first two-dimensional array and the second two-dimensional array are identical.
16. The method of claim 14 , wherein at least one screen is a Hartmann screen.
17. The method of claim 16 , wherein the first screen and the second screen are Hartmann screens.
18. The method of claim 14 , wherein at least one spaced circular aperture of the first screen or second screen includes a lenslet.
19. The method of claim 18 , wherein each of the spaced circular apertures of the first screen and the second screen includes a lenslet.
20. The method of claim 14 , wherein the second screen is rotated about 1 to about 30 degrees relative to the first screen.
21. The method of claim 14 , further comprising directing the light through a relay lens.
22. The method of claim 21 , wherein the relay lens is placed between the second screen and the light detector.
23. The method of claim 21 , wherein the relay lens is placed upstream of the first screen.
24. The method of claim 14 , further comprising directing the light to a beam splitter positioned upstream of the first screen.
25. The method of claim 14 , further comprising selecting a distance between the light source and the first screen, and maintaining the light source stationary during measurement.
26. A method of measuring characteristics of an eye comprising:
a) directing light into the eye;
b) directing the light from the eye through a first screen comprising a first two-dimensional array of spaced circular apertures;
c) directing the light from the first screen through a second screen comprising a second two-dimensional array of spaced circular apertures, wherein the second screen is placed downstream of the first screen, the second screen is in a plane parallel to the first screen, and the second screen is rotated relative to the first screen;
d) detecting the light from the second screen at a light detector.
27. The method of claim 26 , wherein the first two-dimensional array and the second two-dimensional array are identical.
28. The method of claim 26 , wherein at least one screen is a Hartmann screen.
29. The method of claim 28 , wherein the first screen and the second screen are Hartmann screens.
30. The method of claim 26 , wherein at least one spaced circular aperture of the first screen or second screen includes a lenslet.
31. The method of claim 30 , wherein each of the spaced circular apertures of the first screen and the second screen includes a lenslet.
32. The method of claim 26 , wherein the second screen is rotated about 1 to about 30 degrees relative to the first screen.
33. The method of claim 26 , further comprising directing the light through a relay lens.
34. The method of claim 33 , wherein the relay lens is placed between the second screen and the light detector.
35. The method of claim 33 , wherein the relay lens is placed upstream of the first screen.
36. The method of claim 26 , further comprising directing the light to a beam splitter positioned upstream of the first screen.