Dynamic range extension techniques for a wavefront sensor including use in ophthalmic measurement

A system for measuring errors in an eye comprising:

• a projecting optical system which delivers light onto a retina of the eye;
• a pre-correction system which compensates a light beam to be injected into the eye for aberrations in the eye, the pre-correction system being positioned in between the projecting optical system and the eye;
• an imaging system which collects light scattered by the retina;
• a Shack-Hartmann wavefront sensor receiving light returned by the retina from the imaging system;
• and
• an aperture that limits the angular dynamic range of the system.

A wavefront sensor for determining wave aberrations of the eye, comprising:

• a lenslet array adapted to receive an image of a light spot on a retina of an eye and for creating aerial images of the light spot;
• a sensor adapted to receive the aerial images from the lenslet array;
• a processor adapted to receive signals from the sensor corresponding to the aerial images and to determine the wave aberrations from the signals;
• and
• an adjustment camera adapted to aid in bringing into focus onto the sensor the aerial images from the lenslet array.

A wavefront sensor for determining wave aberrations of an eye comprising:

• a lenslet array for receiving an image of light backscattered from a light spot on a retina of the eye and for creating aerial images of the light spot;
• a sensor adapted to receive the aerial images from the lenslet array;
• a processor adapted to receive signals from the sensor corresponding to the aerial images and to determine the wave aberrations from the signals;
• and
• an adjustment camera adapted to aid in bringing into focus the aerial images from the lenslet array onto the sensor.

A method for focusing a wavefront sensor that creates aerial images that form centroids, comprising the steps of:

• monitoring spacing of the centroids;
• adjusting the focus of the sensor;
• and
• determining when the sensor is in focus by determining when the average centroid spacing equals a focused sensor centroid spacing.

A wavefront sensor, comprising:

• a lenslet array adapted to receive an image of a light spot on a retina of an eye and for creating aerial images of the light spot;
• a sensor adapted to receive the aerial images from the lenslet array;
• focusing optics that adjust a focus of the sensor;
• a processor adapted to receive signals from the sensor corresponding to the aerial images and to determine wave aberrations from the signals;
• and
• a focus control system that adjusts the focus of the wavefront sensor by performing a computer implemented method of:
• monitoring spacing of the aerial images;
• adjusting the focus of the sensor;
• and
• determining when the sensor is in focus by determining when an average spacing of the aerial images equals a focused sensor aerial image spacing.

A method for focusing a wavefront sensor that creates aerial images that form centroids, comprising the steps of:

• measuring a total wavefront error incident on the wavefront sensor;
• adjusting the focus of the sensor;
• and
• determining when the sensor is in focus by determining when the total wavefront error incident on the wavefront sensor is minimized.

A wavefront sensor, comprising:

• a lenslet array adapted to receive an image of a light spot on a retina of an eye and for creating aerial images of the light spot;
• a sensor adapted to receive the aerial images from the lenslet array;
• focusing optics that adjust a focus of the sensor;
• a processor adapted to receive signals from the sensor corresponding to the aerial images and to determine wave aberrations from the signals;
• and
• a focus control system that adjusts the focus of the wavefront sensor by performing a computer implemented method of:
• measuring a total wavefront error incident on the wavefront sensor;
• adjusting the focus of the sensor;
• and
• determining when the sensor is in focus by determining when the total wavefront error incident on the wavefront sensor is minimized.