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 light source emitting light along an optical axis;
a first screen comprising a first two-dimensional (2D) array of rounded apertures placed along the optical axis to receive the light from the light source;
a second screen comprising a second 2D array of rounded apertures placed along the optical axis to receive the light from the first screen, wherein the second screen is in a plane parallel to the first screen, and the second screen is rotated relative to the first screen about the optical axis so as to create a Moiré effect; and
a light detector placed to receive light from 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 of the first screen and the second 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 of the first screen and the second screen is a Shack-Hartmann lenslet array.
6. The apparatus of claim 5 , wherein the first screen and the second screen are Shack-Hartmann lenslet arrays.
7. The apparatus of claim 1 , wherein the second screen is rotated between 1 to 30 degrees about the optical axis 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 along the optical axis between the light source and the first screen.
11. The apparatus of claim 1 , further comprising a beam splitter placed along the optical axis between the light source and the first screen.
12. 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 rounded apertures;
c) directing the light from the first screen through a second screen comprising a second two-dimensional array of rounded 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 focused spots of light from the second screen at a light detector.
13. The method of claim 12 , wherein the first two-dimensional array and the second two-dimensional array are identical.
14. The method of claim 12 , wherein at least one screen is a Hartmann screen.
15. The method of claim 14 , wherein the first screen and the second screen are Hartmann screens.
16. The method of claim 12 , wherein at least one screen is a Shack-Hartmann lenslet array.
17. The method of claim 16 , wherein the first screen and the second screen are Shack-Hartmann lenslet arrays.
18. The method of claim 12 , wherein the second screen is rotated about 1 to about 30 degrees relative to the first screen.
19. The method of claim 12 , further comprising directing the light through a relay lens.
20. The method of claim 19 , wherein the relay lens is placed between the second screen and the light detector.