Apparatus and method for operating a real time large diopter range sequential wavefront sensor

• US 8,919,957 B2
• Filed: 11/07/2013
• Issued: 12/30/2014
• Est. Priority Date: 01/20/2006
• Status: Expired due to Fees

• Current Assignee: Clarity Medical Systems, Inc.
• Original Assignee: Clarity Medical Systems, Inc.
• Inventors: Zhou, Yan, Chew, Bradford, Shea, William
• Primary Examiner(s): MAI, HUY KIM
• Application Number:
  US14/074,060
• Publication Number:
  US 20140055749A1
• Time in Patent Office: 418 Days
• Field of Search: 351/205, 351/210, 351/211, 351/212, 351/214, 351/246
• US Class Current: 351/205
• CPC Class Codes: A61B 3/0025 characterised by electronic signal processing, e.g. eye models
• CPC Class Codes: A61B 3/1015 for wavefront analysis
• CPC Class Codes: A61B 3/102 for optical coherence tomography [OCT]
• CPC Class Codes: A61B 3/1035 for measuring astigmatism testing astigmatism A61B3/036
• CPC Class Codes: A61B 3/112 for measuring diameter of pupils
• CPC Class Codes: A61B 3/113 for determining or recording eye movement
• CPC Class Codes: A61B 3/132 in binocular arrangement
• CPC Class Codes: A61B 3/14 Arrangements specially adapted for eye photography apparatus or arrangements for taking photographs per se G03B
• CPC Class Codes: A61B 3/152 for aligning
• CPC Class Codes: A61F 2009/00848 based on wavefront
• CPC Class Codes: G01J 1/0414 using plane or convex mirrors, parallel phase plates, or plane beam-splitters
• CPC Class Codes: G01J 1/0437 using masks, aperture plates, spatial light modulators, spatial filters, e.g. reflective filters
• CPC Class Codes: G01J 2003/064 Use of other elements for scan, e.g. mirror, fixed grating
• CPC Class Codes: G01J 9/00 Measuring optical phase difference devices or arrangements for controlling the phase of light beams G02F1/01; Determining degree of coherence; Measuring optical wavelength spectrometry G01J3/00

Abstract

A sequential wavefront sensor includes a light source, a beam deflecting element, a position sensing detector configured to output a plurality of output signals and a plurality of composite transimpedance amplifiers each coupled to receive an output signal. The output of each composite transimpedance amplifier is phase-locked to a light source drive signal and a beam deflecting element drive signal.

Claims

1. A wavefront sensor comprising:

a light source configured to output a light beam to illuminate a subject eye;

a light source driver circuit coupled to the light source, configured to output a light source drive signal at a first pulsing frequency;

a position sensitive detector having a plurality of detector elements configured to output a plurality of detector output signals indicating signal strength of incident light on each detector element;

a beam deflecting element configured to intercept a wavefront beam returned from a subject eye when the subject eye is illuminated by the light source and configured to direct a portion of the wavefront beam from the subject eye through an aperture toward the detector, where the portion of the wavefront beam directed through the aperture forms a spot on the detector, where an amplitude of deflection of a centroid of the spot from a reference point on the detector is approximately indicated by a ratiometric combination of the signal strengths, and where the amplitude of the deflection indicates the degree of tilt or convergence or divergence of the portion of the wavefront from a plane wave;

a beam deflecting element driving circuit, coupled to the beam deflecting element, configured to output a beam deflecting element drive signal to scan the portion of the wavefront beam at a wavefront scanning frequency; and

a plurality of composite transimpedance amplifiers, each having an input coupled to receive one of the plurality of detector output signals and an output for providing an amplified detector output signal, with the output of each transimpedance amplifier phase-locked to the light source drive signal and the beam deflecting element drive signal.

2. The wavefront sensor of claim 1 with each composite transimpedance amplifier comprising a low pass filter to increase stability and reduce high frequency noise.

3. The wavefront sensor of claim 2 with the low pass filter comprising:

a first operational amplifier U2A having an input and output;

a first resistor R3; and

a first capacitor C3 with the first resistor and capacitor connected in series between the input and output of the first operational amplifier.

4. The wavefront sensor of claim 3 with the composite transimpedance amplifier further comprising:

a second operational amplifier U1A having an input and an output; and

a feedback resistor R1, having a feedback resistance value, coupling the output of the first operational amplifier to the input of the second operational amplifier where the amplitude of the amplified detector output signal is proportional to R1 and the noise is proportional to the square root of R1.