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EP2243007A1 - Système et procédés de détection de front d'onde de diversité de phase - Google Patents

Système et procédés de détection de front d'onde de diversité de phase

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Publication number
EP2243007A1
EP2243007A1 EP08844854A EP08844854A EP2243007A1 EP 2243007 A1 EP2243007 A1 EP 2243007A1 EP 08844854 A EP08844854 A EP 08844854A EP 08844854 A EP08844854 A EP 08844854A EP 2243007 A1 EP2243007 A1 EP 2243007A1
Authority
EP
European Patent Office
Prior art keywords
optical element
detector
lens
phase diversity
wavefront sensor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08844854A
Other languages
German (de)
English (en)
Other versions
EP2243007A4 (fr
Inventor
Thomas D. Raymond
Paul Pulaski
Stephen W. Farrer
Daniel R. Neal
Alan H. Greenaway
David M. Faichnie
Heather I. Campbell Dalgarno
Graham N. Craik
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AMO Wavefront Sciences LLC
Original Assignee
AMO Wavefront Sciences LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by AMO Wavefront Sciences LLC filed Critical AMO Wavefront Sciences LLC
Publication of EP2243007A1 publication Critical patent/EP2243007A1/fr
Publication of EP2243007A4 publication Critical patent/EP2243007A4/fr
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J9/00—Measuring optical phase difference; Determining degree of coherence; Measuring optical wavelength
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J9/00—Measuring optical phase difference; Determining degree of coherence; Measuring optical wavelength
    • G01J2009/002—Wavefront phase distribution
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J9/00—Measuring optical phase difference; Determining degree of coherence; Measuring optical wavelength
    • G01J9/02—Measuring optical phase difference; Determining degree of coherence; Measuring optical wavelength by interferometric methods
    • G01J2009/0203—Phased array of beams

Definitions

  • This invention pertains to the field of wavefront measurements, and more particularly to systems and methods of measuring a wavefront of light using a phase diversity wavefront sensor. [0003] Description.
  • a number of systems and methods have been developed for measuring a wavefront of light. Such wavefront measurements have been employed in a number of applications, including ophthalmic applications such as measuring aberrations of an eye, and measuring surfaces of objects such as contact lenses.
  • SHWS Shack Hartmann wavefront sensor
  • a SHWS includes an array of lenslets which image focal spots onto a detector array.
  • SHWS 's have been employed in a variety of ophthalmic and metro logical applications.
  • a SHWS has some limitations in certain applications.
  • the wavefront is expected to produce a single local tilt.
  • an SHWS has difficulty measuring wavefronts with discontinuities.
  • the wavefront may have multiple tilts, which may produce multiple focal spots.
  • such discontinuities can be produced by multi-focal optical devices, including multifocal contact lenses and multifocal intraocular lenses (IOL).
  • IOL multifocal intraocular lenses
  • W. Neil Charman et al., "Can we measure wave aberration inpatients with diffractive IOLs? " 33 JOURNAL OF CATARACT & REFRACTIVE SURGERY NO. 11, p. 1997 (Nov. 2007) discusses some problems in using a SHWS to make wave front measurements of a patient with a diffractive IOL. Charman notes that when a measurement is taken on an eye that has been implanted with a diffractive IOL, the lenslets of the SHWS will produce multiple images and the detector will record multiple overlapping spot patterns. So, it is difficult at best for a SHWS to measure wavefronts produced by multifocal optical elements, such as diffractive IOLs.
  • Another limitation of the SHWS pertains to its limited dynamic range. For example, to measure ophthalmic aberrations of a human eye over the wide range presented by the human population, as a practical matter one needs to employ an adjustable optical system in conjunction with the SHWS so that operation of the SHWS can be maintained within its dynamic range. This can add to the complexity and cost of the measurement system, and requires alignment that can reduce the measurement precision of the instrument.
  • Another type of wavefront sensor is a phase diversity wavefront sensor (PDWS), also sometimes referred to as a curvature sensor.
  • PDWS phase diversity wavefront sensor
  • a PDWS may be used to analyze wavefronts at two or more planes that are generally orthogonal to the direction of propagation of an optical beam.
  • a PDWS measurement system makes measurements via an optical system that is capable of imaging two or more planes at once, to minimize or eliminate the effects of any time -varying changes in the optical beam.
  • Graves et al. U.S. Patent 6,439,720 describes a measurement system that includes a PDWS.
  • Early PDWS systems employed a relatively complex arrangement of beam splitters and/or optical delays to generate the necessary images.
  • Blanchard, P. B and Greenaway, A.H. "Simultaneous Multi-plane Imaging with a Distorted Diffraction Grating"
  • APPLIED OPTICS (1999) (“Blanchard") disclosed the use of a diffractive optical element (DOE) in a PDWS.
  • DOE diffractive optical element
  • the DOE uses local displacement of lines in a diffraction grating to introduce arbitrary phase shifts into wave fronts diffracted by the grating into the non-zero orders to create multiple images of the incident light.
  • a diffraction grating having a quadratic displacement function is employed in conjunction with a collocated single lens to alter the optical transfer function associated with each diffraction order such that each order has a different degree of defocus.
  • references are not generally directed to applications where there is speckle and/or discontinuities or large aberrations in the wavefront, such as may be the case in many ophthalmic applications, including the measurement of IOLs, multifocal contact lenses, etc., and eyes or optical systems that include such devices. Furthermore, these references do not provide a generalized design method for incorporating a PDWS into more complicated optical systems. [00013] It would be desirable to provide an ophthalmic measurement instrument that utilizes the benefits of a PDWS, alone or in conjunction with a SHWS. It would further be desirable to provide such an instrument that can measure wavefronts with speckle and/or discontinuities or large aberrations in the wavefront.
  • a multifocal element such as an intraocular or contact lens that is either a refractive multifocal lens, a diffractive multifocal lens, or a diffractive monofocal lens. It would also be desirable to provide a generalized method of designing a measurement system including a PDWS.
  • a phase diversity wavefront sensor comprises: an optical system including at least one optical element for receiving a light beam; a diffractive optical element having a diffractive pattern defining a filter function, the diffractive optical element being arranged to produce, in conjunction with the optical system, images from the light beam associated with at least two diffraction orders; and a detector for detecting the images and outputting image data corresponding to the detected images, wherein the optical system, diffractive optical element, and detector are arranged to provide telecentric, pupil plane images of the light beam.
  • a method for measuring a wavefront of an optical system including a multifocal element comprises: providing a light beam to a lens, the lens being a refractive multifocal lens, a diffractive multifocal lens, or a diffractive monofocal lens; directing light from the lens to a phase diversity wavefront sensor, comprising an optical system including at least one optical element for receiving a light beam, and a diffractive optical element the shape of which is defined by a filter function, the diffractive optical element being arranged to produce in conjunction with the optical system images of the light beam associated with at least two diffraction orders; and a detector for detecting the images and outputting image data corresponding to the detected images; and measuring the wavefront of the light from the lens using the image data output by the detector.
  • a method for measuring a wavefront of an object having first and second surfaces.
  • the method comprises: providing a light beam to the object; directing light from the lens to a phase diversity wavefront sensor, the lens being a refractive multifocal lens, a diffractive multifocal lens, or a diffractive monofocal lens, the phase diversity wavefront sensor comprising an optical system including at least one optical element for receiving a light beam, and a diffractive optical element the shape of which is defined by a filter function, the diffractive optical element being arranged to produce in conjunction with the optical system images of the light beam associated with at least two diffraction orders; and a detector for detecting the images and outputting image data corresponding to the detected images; and simultaneously measuring the first and second surfaces of the object using the image data output by the detector.
  • a method for designing a phase diversity wavefront sensor. The method comprises: providing one or more analytic solutions for paraxial equations that govern an optical configuration of the phase diversity wavefront sensor; providing a set of input design parameters for the phase diversity wavefront sensor; generating a set of output values from the analytical solutions and the input design parameters; and determining whether the output parameters meet a viability threshold.
  • a phase diversity wave front sensor comprises: an illuminating optical system for delivering light onto a retina of an eye; a receiving optical system for receiving light reflected by the retina, the receiving optical system comprising a diffractive optical element including a diffraction pattern defining a filter function, the diffractive optical element being arranged to produce, in conjunction with the optical system, at least two images from the light beam associated with at least two diffraction orders; a detector for detecting the at least two images; a memory containing instructions for executing a Gerchberg-Saxton phase retrieval algorithm on data produced by the detector in response to the detected images; and a processor configured to execute the Gerchberg-Saxton phase retrieval algorithm so as to characterize a wavefront produced by the reflected light.
  • FIG. 1 illustrates the use of a diffractive optical element (DOE) in a phase diversity wavefront sensor (PDWS).
  • DOE diffractive optical element
  • FIG. 2 illustrates an intensity image produced by the PDWS of FIG. 1.
  • FIG. 3 illustrates another configuration of a PDWS.
  • FIG. 4 illustrates one embodiment of diffraction grating.
  • FIG. 5 illustrates an intensity image produced by the PDWS of FIG. 3.
  • FIG. 6 illustrates operation of one embodiment of a Gerchberg-Saxton (GS) algorithm.
  • FIG. 7 illustrates propagation from one measurement plane to the next.
  • FIG. 8 illustrates the numerically calculated defocus versus iteration number in a
  • FIG. 9 plots the number of iterations in a GS algorithm required to reduce the defocus error to less than 0.01 diopters versus pupil diameter.
  • FIG. 10 plots the number of iterations in a GS algorithm required for convergence versus sample plane separation for a given beam diameter.
  • FIG. 11 illustrates the numerically calculated defocus versus iteration number in a
  • FIG. 12 plots the number of iterations required to reduce the defocus error to less than 0.01 diopters versus pupil diameter for a speckled beam, compared to a beam without speckle.
  • FIGs. 13A-C illustrate basic ophthalmic aberrometer designs for SHWS and PDWS sensors.
  • FIG. 14 illustrates a simplified design of a PDWS with a large dynamic range.
  • FIG. 15 illustrates a process of designing a measurement system that includes a
  • FIG. 16 illustrates how the process of FIG. 15 establishes design tradeoffs by comparing design points.
  • FIG. 17 illustrates how a PDWS can be used to measure both surfaces of a contact lens.
  • FIGs. 18A-C illustrate the use of a PDWS in an ophthalmic measurement application.
  • FIG. 19 illustrates a block diagram of one embodiment of an ophthalmic aberrometer that includes a PDWS.
  • FIG. 1 illustrates the use of a diffractive optical element (DOE) in a phase diversity wavefront sensor (PDWS) 100.
  • PDWS 100 includes an optical element 110, a detector 120, and a processor 130.
  • Optical element 110 includes a diffractive optical element (DOE) (e.g., a diffraction grating) 112 collocated with optical element 114 with positive focal power.
  • DOE diffractive optical element
  • optical element 110 may alternately be used in reflection where diffraction grating 114 is collocated with optical element 114 comprising a mirror.
  • optical element 114 is a lens, and diffractive grating
  • lens 112 is disposed on a surface of lens 114.
  • diffractive grating 112 may be incorporated inside lens 114 or be formed from the material used to form lens 114.
  • lens 114 and diffractive grating 112 form a single DOE, where lens 114 is itself a DOE, for example, disposed on a same surface or an opposite surface as diffractive grating 112.
  • lens 114 and grating 112 are separate elements that touch one another or are separated by a relatively small distance. Element 114 could be refractive, diffractive or reflective.
  • Detector 120 may be a charge coupled device (CCD).
  • CCD charge coupled device
  • diffraction grating 112 is distorted by a quadratic filter function so that optical element 110 introduces an optical power that depends upon the diffraction order.
  • Optical element 110 produces angularly displaced beams with different focal power.
  • the combination of diffraction grating 112 and lens 114 yields a net optical power given by:
  • m is the diffraction order of diffraction grating 112
  • R the aperture radius of diffraction grating 112
  • W20 is a standard defocus term specifying the phase shift from center to edge of the optic. This is related to the quadratic distortion in the grating as specified by Blanchard. Note that the grating period in such distorted gratings is not constant, but can still be specified in terms of an average period at the DOE center. This grating period is the average distance between the lines in the grating and, together with the wavelength of the incident light, determines the diffraction angle of the diffracted beams, and hence their separation on the detector array.
  • diffraction grating 112 is distorted by a filter function that is non-quadratic and has non-mixed symmetry.
  • detector 120 is located at the focal plane for the 0 th order beam and is referred to as an "image plane PDWS.”
  • FIG. 2 illustrates an intensity image produced by PDWS 100.
  • This arrangement produces a real image at the +1 diffraction order, a virtual image at the -1 diffraction order, and a far field pattern at the 0 diffraction pattern. As can be seen in FIG. 2, this produces a bright spot 0 th order beam, and dimmer spots for the
  • Data acquisition may be accomplished by two-dimensional digitization of the intensity image at detector 120.
  • the image data is then supplied to processor 130 for further analysis to measure the wavefront of plane wave 10.
  • FIG. 3 illustrates another configuration of a PDWS 300.
  • PDWS 300 comprises an optical element (e.g., a lens) 310, a diffractive optical element (e.g., a diffraction grating)
  • an optical element e.g., a lens
  • a diffractive optical element e.g., a diffraction grating
  • Detector 330 may comprise a charge coupled device (CCD).
  • PDWS 300 possesses certain characteristics that may be beneficial for measuring wavefronts in ophthalmic applications, as will be discussed in greater detail below.
  • memory 345 Associated with processor 340 is memory 345 containing instructions for executing a phase retrieval algorithm on data produced by detector 330.
  • FIG. 4 illustrates one embodiment of diffraction grating 320.
  • diffraction grating 320 In one embodiment of
  • diffraction grating 320 comprises a distorted grating that is distorted by a quadratic filter function. This is also known as an off-axis Fresnel lens.
  • diffraction grating 320 is distorted by a filter function that is non-quadratic and has non-mixed symmetry.
  • FIG. 5 illustrates an intensity image produced by PDWS 300.
  • PDWS 300 In contrast to PDWS
  • PDWS 300 forms real images of the beam at both sample planes and at the measurement plane (the Pupil Plane). Accordingly,
  • PDWS 300 is referred to as a "Pupil Plane PDWS.”
  • PDWS 300 forms images of the beam 350 at different sample locations, and these images are laterally displaced at camera 330 so that they can be simultaneously acquired.
  • PDWS 300 can be thought of as producing multiple object planes (also referred to as "observation planes" or “sample planes') that are imaged onto camera 330.
  • object plane u_i is imaged onto the -1 th order beam
  • object plane uo is imaged onto the 0 th order beam
  • object plane u + i is imaged onto the +l th order beam at camera.
  • FIG. 3 illustrates an example with a converging beam
  • a collimated beam or a diverging beam may be employed in a particular application.
  • FIG. 3 illustrates three "observation planes" it should be understood that more observation planes corresponding to additional diffraction orders can be employed and that only two observation planes are necessary in many applications.
  • having a multitude of observation planes can provide a greater dynamic range, greater sensitivity, improved ability to discern waves with multiple wavefronts.
  • Data acquisition may be accomplished by two-dimensional digitization of the intensity values detected by camera 330.
  • the detected intensity data may then be analyzed by processor 340 to determine the phase distribution that produces the intensity measured in all planes, as will now be explained in detail.
  • the axial derivative is not known, it is approximated by the finite difference between the intensity measurements along the propagation direction as shown in EQN. 2 above. This approximation fails for beams with aberrations large enough to significantly change the beam size between the sample planes. As such properties may be found in beams in ophthalmic applications, the use of ITE-based phase retrieval methods is of limited utility, for example, for a PDWS employed in an ophthalmic aberrometer.
  • FIG. 6 illustrates operation of one embodiment of the GS algorithm.
  • processor 340 estimates, or guesses, ⁇ (x,y).
  • processor 340 takes the latest estimate of ⁇ (x,y) and propagates it to the next measurement plane. Then, processor 340 replaces the amplitude of the propagated field with the square root of the intensity measurement at that plane. Processor 340 then propagates this data to the next measurement plane, and the process is repeated for all measurement planes until the propagated intensity matches the measured sufficiently well (e.g., the difference is less than a defined threshold). If necessary, the process may proceed from the ⁇ _i measurement plane, to the ⁇ o measurement plane, to the ⁇ + i measurement plane, and back to the ⁇ o measurement plane, then to the ⁇ _i measurement plane, etc., until convergence is reached.
  • processor 340 employs a Rayleigh-Sommerfeld propagation integral to propagate from one measurement plane to the next.
  • FIG. 7 illustrates this propagation. Given the data ⁇ i( ⁇ , ⁇ ) at a first measurement plane ⁇ ls then the data is propagated to a second measurement plane, ⁇ i, to produce propagated data ⁇ 2 (x,y) as follows:
  • the inventors have investigated the efficacy of the iterative GS phase retrieval method in ophthalmic instruments where large dynamic range in defocus and the presence of speckle make phase retrieval with standard methods based on the intensity transport equation difficult.
  • Simulated PDWS data covering a typical range of ophthalmic defocus aberrations with a standard PDWS configuration were generated using the Rayleigh-Sommerfeld propagation integral equation.
  • Speckled beams were simulated by imposing a random phase distribution with amplitude several radians on a uniform beam and propagating several millimeters. The size of the speckle cells of the resulting intensity distributions averaged about 1 mm.
  • FIG. 8 illustrates the numerically calculated defocus versus iteration number for different pupil diameters.
  • FIG. 9 plots the number of iterations required to reduce the defocus error to less than 0.01 diopters versus pupil diameter.
  • FIGs. 8 and 9 show that convergence is rapid for small diameter beams but is much slower as the beam diameter increases.
  • the number of iterations required to achieve a specified level of defocus accuracy increases approximately exponentially with input pupil diameter for fixed sample spacing.
  • FIG. 10 plots the number of iterations required for convergence versus sample plane separation for a given beam diameter. It can be seen in FIG. 10 that the convergence rate improves with sample plane separation.
  • FIG. 11 illustrates the numerically calculated defocus versus iteration number for different pupil diameters in the case of an irradiance pattern where speckle is introduced.
  • FIG. 12 plots the number of iterations required to reduce the defocus error to less than 0.01 diopters versus pupil diameter for a speckled beam (lower plot), compared to a beam without speckle (upper plot).
  • the number of iterations required to achieve a specified level of defocus accuracy increases approximately quadratically with input pupil diameter for fixed sample spacing, rather than exponentially, as is the case with beams that do not include speckle.
  • the dynamic range and sensitivity can be controlled by proper selection of the sample plane spacing and the number of bits of digitization of the CCD in camera 330.
  • PDWS 300 provides a wide dynamic range so as to accommodate a wide range of aberrations in the input wavefront without the need to move or adjust any optical elements, thus simplifying the construction of an ophthalmic measurement instrument.
  • PDWS 300 is capable of measuring the wavefronts of beams with at least + 3 diopters of defocus. Further beneficially, in one embodiment PDWS 300 is capable of measuring the wavefronts of beams with at least + 5 diopters of defocus. Even further beneficially, in one embodiment PDWS 300 is capable of measuring the wavefronts of beams with at least + 10 diopters of defocus.
  • PDWS 300 includes a number of features that are desirable for an ophthalmic measurement system.
  • Pupil plane imaging provides a real image of the pupil and accommodates variability in the location, size and shape of a human pupil when making aberrometer measurements, especially because the location of a patient's eye is generally not well controlled.
  • Pupil Plane Imaging is also beneficial in resolving the phase of a speckled beam, or a wavefront having one or more discontinuities.
  • PDWS 300 may employ telecentric imaging. Telecentric imaging provides equally spaced sample planes, and provides equal magnification for all images.
  • Telecentric imaging simplifies the alignment, calibration, and data processing of PDWS 300.
  • FIGs. 13A-C illustrate basic ophthalmic aberrometer designs for SHWS and PDWS sensors.
  • the ophthalmic aberrometer will include a light projection system for creating the light beam and directing it to an eye or other object that is being measured.
  • the wavefront u 0 may be an image of a wavefront at a pupil or corneal surface of an eye under examination.
  • FIG. 13A illustrates an exemplary design for an ophthalmic aberrometer 1300A employing a SHWS 1310A.
  • SHWS 1310A includes a lenslet array 1312A and a camera, or pixel array 1314A, also called a detector array.
  • the design employs a Badal Relay Imager
  • a processor 1350A processes data produced by camera 1314A.
  • both the spatial resolution and the dynamic range are correlated to the dimension of the lens lets in lenslet array 1312A.
  • the optical system typically demagnifies the pupil image to fit on SHWS 1310A and the distance between lenses 1322A and 1324A is adjusted to add defocus to compensate the incoming wavefront so that it lies within the dynamic range of SHWS 131OA.
  • Preservation of the optical phase front is important with SHWS 1310A, and image quality is generally a secondary consideration in the optical design.
  • the sensitivity of SHWS 1310A is set by the lenslet focal length and the pixel size in camera 1314A and is adjusted to give a predetermined sensitivity.
  • the sensitivity and spatial resolution requirements typically limit the dynamic range of SHWS 130 IA to a few diopters.
  • the system can be dynamically adjusted to produce a larger effective dynamic range by moving one or both of the lenses 1322A and l324A.
  • FIG. 13B illustrates an exemplary design for an ophthalmic aberrometer 1300B where a PDWS 1330B replaces the SHWS 1310A of FIG. 13 A.
  • PDWS 1330B includes lens 1332B, diffraction grating 1333B and camera, or pixel array 1334B, also called a detector array.
  • a processor 1350B processes data produced by camera 1334B.
  • the arrangement of aberrometer 1300B is unnecessarily complex.
  • FIG. 13C illustrates an exemplary design for an ophthalmic aberrometer 1300C is tailored for PDWS 1330C.
  • Aberrometer 1330C includes lens 1332C, diffraction grating 1333C and camera, or pixel array 1334C, also called a detector array.
  • a processor 1350C processes data produced by camera 1334C.
  • FIG. 14 illustrates a simplified design of a PDWS with a large dynamic range.
  • FIG. 14 shows a first lens 1410, a second lens 1420, a diffraction grating 1430, a camera 1440, and a processor 1450.
  • Analytic solutions with Pupil Plane and Telecentric Imaging and the use of static optical elements will be explained with respect to FIG. 14.
  • an analytic solution is performed for the paraxial equations that govern the particular optical configuration of interest, using ray matrix analysis, to determine the proper arrangement to provide telecentric imaging.
  • the telecentric solution can be found by imposing the appropriate constraints on the general imaging solution; these constraints select the subset of the general paraxial imaging solutions with magnification independent of grating order, or equivalently, object positions that depend purely linearly on grating order.
  • the object plane locations for all images depend linearly on the grating order and the image magnifications are independent of the grating order for an optical configuration consisting of two lenses followed by a grating as shown in Figure 13C.
  • the lens focal lengths are respectively / ⁇ and/ the grating focal length in first order isf g , m is the grating order, s is the distance between the second lens and the grating, t is the distance between the lenses and v is the space between the second lens and the detector array. Equation 5 shows the general solution for the telecentric pupil plane Lens-Lens-Grating PDWS.
  • the general telecentric pupil plane imaging PDWS equations shown above describe a family of solutions in which s, v and t are related for a given set of lens and grating focal lengths.
  • Table 1 below shows representative examples of the family of analytic paraxial solutions for the Lens-Lens-Grating configuration of FIG. 14, derived using a symbolic manipulator (e.g., MATHEMATICA®) as shown in Equation 5, that provide both telecentric and pupil plane imaging for static lens positions for specific values of t and v.
  • a symbolic manipulator e.g., MATHEMATICA®
  • the sample plane locations ⁇ M are linear in grating order, m, and the magnification is independent of grating order, characteristics of a telecentric imaging system.
  • ⁇ M e.g., ⁇ _i , ⁇ o , ⁇ + i
  • the solution with t is a telecentric pupil plane PDWS where the second lens and grating co- located; although this looks similar to the image plane sensor, the judicious positioning of each optical element provides the additional functionality of the pupil plane PDWS.
  • FIG. 15 illustrates a process 1500 of designing a measurement system that includes a PDWS.
  • a first step 1510 the analytical solutions are imported into a spreadsheet to explore the performance of the system versus input design parameters.
  • input design parameters are provided.
  • the inputs may include the optical configuration, the location of the pupil plane, the desired dynamic range.
  • outputs are generated based on the analytical solutions and the input design parameters. Outputs may include sensitivity, system length, actual dynamic range, etc.
  • a step 1540 it is determined whether a viable design has been produced. If not, then the process returns to step 1520 and new input parameters are provided. If a viable deign has been achieved, then a detailed analysis is performed in step 1550. [00083] FIG.
  • FIG. 16 illustrates how the process of FIG. 15 establishes design tradeoffs by comparing design points.
  • FIG. 16 plots sensitivity versus pupil plane location. So, for example, if the system requires a sensitivity of at least 0.01 diopters and a stand-off distance between 73 and 375 mm, as illustrated in FIG. 16, an acceptable performance range exists and final detailed ray matrix analysis of this system configuration is warranted as it is a viable design.
  • This design method is beneficial in assisting in the early rejection of candidate configurations before significant investment is made in their detailed analysis; in contrast, traditional design methods do not permit the elimination of such unviable candidate configurations without the expense of a detailed ray matrix analysis. [00084]
  • FIG. 16 plots sensitivity versus pupil plane location. So, for example, if the system requires a sensitivity of at least 0.01 diopters and a stand-off distance between 73 and 375 mm, as illustrated in FIG. 16, an acceptable performance range exists and final detailed ray matrix analysis of this system configuration is warranted
  • a PDWS 1700 such as PDWS 300 or PDWS 1400, can be used to measure both surfaces of a lens 17, for example, a contact lens or an intraocular lens.
  • Light from a light source 1710 is passed through a beamsplitter 1720 to lens 17. Reflections are produced from both surfaces of lens 17 and pass back through beamsplitter to the PDWS 1700 which has sample planes located about the focal positions of the light reflected from the two lens surfaces.
  • the advantages of PDWS 1700 can be seen. For example, if a SHWS were employed in this application, the multiple reflections from the surfaces of lens 17 would generate multiple focal spots from its lenslet array that could confuse the processor associated with a SHWS.
  • PDWS 1700 can easily distinguish between the two reflected wavefronts, and therefor both surfaces of lens 17 can be characterized.
  • the wave reflected from each surface will focus at different distances from the lens; it is obvious that by suitably placing sufficient PDWS sample planes near these foci, sufficient data can be made available to a Gerchberg-Saxton phase retrieval algorithm to determine the wavefront from each surface and hence the optical effect of each surface. More than two sample planes may be required in such multi wavefront applications and their number and locations may be expected to affect the accuracy of the phase retrieval.
  • FIGs. 18A-C illustrate the use of a PDWS in an ophthalmic measurement application.
  • FIGs. 18A-C show ray trace results from a non-paraxial analysis.
  • the PDWS configuration illustrated in FIGs. 18A-C has a 300 mm pupil plane (standoff) distance, and the camera has 300 pixels across a width of 6 mm.
  • FIG. 18A illustrates a case where +10 diopters of ophthalmic correction are required
  • FIG. 18B illustrates a case where 0 diopters of ophthalmic correction are required
  • FIG. 18C illustrates a case where -10 diopters of ophthalmic correction are required.
  • FIG. 18A-C shows that light rays are fully transmitted to the camera in this arrangement for beams within the range + 10 diopters of defocus; for this reason, this configuration is suitable to acquire the data necessary to analyze beams with this wide range of defocus. Indeed even larger ranges may be possible by increasing the diameter of the second lens.
  • the detailed ray trace analysis of such a system employing realistic commercially available lenses shows that the non-paraxial behavior of the system magnification departs from ideal by only about 1.3% at the extremes of the dynamic range, well within the acceptable tolerance for an ophthalmic aberrometer.
  • Ophthalmic aberrometer 1900 illustrates a block diagram of one embodiment of an ophthalmic aberrometer 1900 that includes a PDWS 1910, which for example can be PDWS 300 or PDWS 1400.
  • Ophthalmic aberrometer 1900 also includes a light source 1920, an optical system 1930, and a processor 1950.

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  • Eye Examination Apparatus (AREA)

Abstract

L'invention concerne un capteur de front d'onde de diversité de phase qui comprend un système optique comprenant au moins un élément optique pour recevoir un faisceau lumineux; un élément optique diffractif ayant un schéma diffractif définissant une fonction de filtre, l'élément optique diffractif étant disposé pour produire, conjointement au système optique, des images du faisceau lumineux associées à au moins deux ordres de diffraction; et un détecteur pour détecter les images et émettre des données d'images correspondant aux images détectées. Dans un mode de réalisation, le système optique, l'élément optique diffractif et le détecteur sont disposés de sorte à fournir des images planes de pupille, télécentriques du faisceau lumineux. Un processeur reçoit les données d'images du détecteur et exécute un algorithme de récupération de phase de Gerchberg-Saxton pour mesurer le front d'onde du faisceau lumineux.
EP08844854.3A 2007-10-30 2008-10-28 Système et procédés de détection de front d'onde de diversité de phase Withdrawn EP2243007A4 (fr)

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US98383007P 2007-10-30 2007-10-30
US2887708P 2008-02-14 2008-02-14
US4804208P 2008-04-25 2008-04-25
PCT/US2008/081402 WO2009058747A1 (fr) 2007-10-30 2008-10-28 Système et procédés de détection de front d'onde de diversité de phase

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EP2243007A1 true EP2243007A1 (fr) 2010-10-27
EP2243007A4 EP2243007A4 (fr) 2017-03-01

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AU (1) AU2008318889B2 (fr)
CA (2) CA2713418C (fr)
WO (1) WO2009058747A1 (fr)

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CN113203485B (zh) * 2021-04-27 2022-08-05 浙江大学 一种通过单次曝光实现轴向相位差波前重建的装置及方法

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Publication number Publication date
EP2243007A4 (fr) 2017-03-01
AU2008318889B2 (en) 2014-01-23
CA2912003A1 (fr) 2009-05-07
WO2009058747A1 (fr) 2009-05-07
CA2912003C (fr) 2017-07-18
CA2713418C (fr) 2016-01-26
AU2008318889A1 (en) 2009-05-07
CA2713418A1 (fr) 2009-05-07

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