Methods and apparatus for assessment of refractive condition
In exemplary implementations of this invention, an aberrometer is used to measure the refractive condition of any eye. An artificial light source emits light that travels to a light sensor. Along the way, the light enters and then exits the eye, passes through or is reflected from one or more spatial light modulators (SLMs), and passes through an objective lens-system. The SLMs modify a bokeh effect of the imaging system (which is only visible when the system is out-of-focus), creating a blurred version of the SLM patterns. The light sensor then captures one or more out-of-focus images. If there are refractive aberrations in the eye, these aberrations cause the SLM patterns captured in the images to be distorted. By analyzing differences between the distorted captured patterns and the undistorted SLM patterns, refractive aberrations of the eye can be computed and an eyewear measurement generated.
1. A method comprising:
(a) capturing, with a light sensor, an unfocused image of a first spatial light modulator (SLM), which unfocused image is formed by light that has entered and exited an eye and then passed through a first lens-system;
(b) analyzing differences between a first visual pattern and a second visual pattern; and
(c) computing a refractive aberration of the eye, based at least in part on the differences;
wherein
(1) the first SLM is positioned optically between the eye and the light sensor,
(2) the first visual pattern comprises the unfocused image or comprises a transformation of the unfocused image,
(3) the second visual pattern comprises a second image of the first SLM that is not distorted by the refractive aberration of the eye,
(4) an artificial light source emits the light,
(5) a second SLM is positioned optically between the light source and the eye,
(6) the light passes through a second lens system that is optically between the light source and the eye, and
(7) the second lens system has an optical power that prevents the eye from focusing on the second SLM and from focusing on the light source.
2. The method of claim 1 , wherein:
(a) the light sensor is housed in a mobile computing device; and
(b) the first lens-system is located in the mobile computing device.
3. The method of claim 2 , wherein the first SLM is housed in a device that is releasably attached to the mobile computing device.
4. The method of claim 1 , wherein the refractive aberration is myopia, hyperopia or astigmatism.
5. The method of claim 1 wherein the refractive aberration is keratoconus, optical coma, or trefoil.
6. The method of claim 1 , wherein the light is in a collimated state before it enters the eye.
7. The method of claim 1 , wherein the light is in an uncollimated state immediately before the light enters the eye.
8. A method comprising:
(a) capturing, with a light sensor, an unfocused image of a spatial light modulator (SLM), which unfocused image is formed by light that has entered and then exited an eye and then passed through a lens-system;
(b) analyzing differences between a first visual pattern and a second visual pattern; and
(c) computing a first refractive aberration of the eye, based at least in part on the differences;
wherein
(1) the SLM is positioned optically between the eye and an artificial light source that emits the light,
(2) the first visual pattern comprises the unfocused image or comprises a transformation of the unfocused image,
(3) the second visual pattern comprises a second image of the SLM that is not distorted by the first refractive aberration of the eye, and
(4) the unfocused image is unfocused due to reasons other than the first refractive aberration and other than any other refractive aberration of the eye.
9. The method of claim 8 , wherein:
(a) the light passes through a second lens-system after exiting the light source and before entering the eye; and
(b) the second lens-system refracts the light in such a way that the eye cannot focus on the SLM and cannot focus on the light source.
10. The method of claim 8 , wherein:
(a) the light sensor is housed in a mobile computing device; and
(b) the lens-system that is mentioned in claim 8 is located in the mobile computing device.
11. The method of claim 8 , wherein the refractive aberration is myopia, hyperopia or astigmatism.
12. The method of claim 8 , wherein the refractive aberration is keratoconus, optical coma, or trefoil.
13. The method of claim 8 , wherein the light is in an uncollimated state immediately before the light enters the eye.
14. The method of claim 8 , wherein the SLM is housed in a device that is releasably attached to the mobile computing device.