A Shack–Hartmann (or Hartmann–Shack) wavefront sensor (SHWFS) is an optical instrument used for characterizing an imaging system.[1][2] It is a wavefront sensor commonly used in adaptive optics systems. It consists of an array of lenses (called lenslets) of the same focal length. Each is focused onto a photon sensor (typically a CCD array or CMOS array[3] or quad-cell[4]). If the sensor is placed at the geometric focal plane of the lenslet,[5] and is uniformly illuminated,[6] then, the integrated gradient of the wavefront across the lenslet is proportional to the displacement of the centroid. Consequently, any phase aberration can be approximated by a set of discrete tilts. By sampling the wavefront with an array of lenslets, all of these local tilts can be measured and the whole wavefront reconstructed. Since only tilts are measured the Shack–Hartmann cannot detect discontinuous steps in the wavefront.
Shack–Hartmann system in clinical optics: Laser creates a virtual light source in the retina. The lenslet array creates spots in the sensor according to the wavefront coming out of the eye.Inverse of the Shack–Hartmann system in clinical optics: A set of patterns is displayed on the screen, the user aligns/overlaps them in a single image pressing buttons.A schematic illustration of a SHWFS.Operations of a single lenslet in a SHWFS.
The design of this sensor improves upon an array of holes in a mask that had been developed in 1904 by Johannes Franz Hartmann as a means of tracing individual rays of light through the optical system of a large telescope, thereby testing the quality of the image.[2] In the late 1960s, Roland Shack and Ben Platt modified the Hartmann screen by replacing the apertures in an opaque screen by an array of lenslets.[7][1] The terminology as proposed by Shack and Platt was Hartmann screen. The fundamental principle seems to be documented even before Huygens by the Jesuit philosopher, Christopher Scheiner, in Austria.[8]
Shack–Hartmann sensors are used in astronomy to measure telescopes and in medicine to characterize eyes for corneal treatment of complex refractive errors.[9][10] Recently, Pamplona et al.[11] developed and patented[12] an inverse of the Shack–Hartmann system to measure one's eye lens aberrations. While Shack–Hartmann sensors measure the localized slope of the wavefront error using spot displacement in the sensor plane, Pamplona et al. replace the sensor plane with a high resolution visual display (e.g. a mobile phone screen) that displays spots that the user views through a lenslet array. The user then manually shifts the displayed spots (i.e. the generated wavefront) until the spots align. The magnitude of this shift provides data to estimate the first-order parameters such as radius of curvature and hence error due to defocus and spherical aberration.
Referencesedit
^ ab Shack, R.V. (1971). Smith, F. Dow (ed.). "Production and use of a lenticular Hartmann screen". Journal of the Optical Society of America (Oral presentation). Ramada Inn, Tucson, Arizona. 61 (5): 656.
^ ab Hartmann, J. (1904). "Objektivuntersuchungen". Zeitschrift für Instrumentenkunde. Berlin: Verlag von Julius Springer. 24: 1–25, 33–47, 97–117.
^ T Nirmaier; G Pudasaini; J Bille (2003). "Very fast wave-front measurements at the human eye with a custom CMOS-based Hartmann-Shack sensor". Optics Express. OSA. 11 (21): 2704–2716. Bibcode:2003OExpr..11.2704N. doi:10.1364/oe.11.002704. PMID 19471385.
^ LP Salles; DW de Lima Monteiro (2010). "Designing the response of an optical quad-cell as position-sensitive detector". IEEE Sensors Journal. IEEE. 10 (2): 286–293. Bibcode:2010ISenJ..10..286S. doi:10.1109/jsen.2009.2033806.
^Akondi, Vyas; Dubra, Alfredo (August 2019). "Accounting for focal shift in the Shack–Hartmann wavefront sensor". Optics Letters. 44 (17): 4151–4154. doi:10.1364/OL.44.004151. PMC7535119. PMID 31465350.
^Akondi, Vyas; Steven, Samuel; Dubra, Alfredo (August 2019). "Centroid error due to non-uniform lenslet illumination in the Shack–Hartmann wavefront sensor". Optics Letters. 44 (17): 4167–4170. doi:10.1364/OL.44.004167. PMC7535117. PMID 31465354.
^ Platt, Ben C.; Shack, Ronald (October 2001). "History and Principles of Shack-Hartmann Wavefront Sensing". Journal of Refractive Surgery. 17 (5): S573–7. doi:10.3928/1081-597X-20010901-13. PMID 11583233.
^Scheiner, "Oculus, sive fundamentum opticum", Innsbruck 1619
^ E. Moreno-Barriuso & R. Navarro (2000). "Laser ray tracing versus Hartmann--Shack sensor for measuring optical aberrations in the human eye". JOSA A. Optical Society of America. 17 (6): 974–985. Bibcode:2000JOSAA..17..974M. doi:10.1364/JOSAA.17.000974. hdl:10261/61848. PMID 10850467.
^ Thomas Kohnen & Douglas D. Koch (2006). Cataract and refractive surgery, Volume 2. Springer. p. 55. ISBN978-3-540-30795-2.
^ Pamplona, Vitor F.; Mohan, Ankit; Oliveira, Manuel M.; Raskar, Ramesh (2010). (PDF). ACM Transactions on Graphics. 29 (4). doi:10.1145/1778765.1778814. hdl:1721.1/80392. Archived from the original (PDF) on 2012-10-12.
^US patent 8783871, Pamplona, Vitor; Menezes de Oliveira, Manuel & Mohan, Ankit et al., "Near eye tool for refractive assessment", published 2013-01-31, issued 2014-07-22, assigned to Massachusetts Institute of Technology
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A Shack Hartmann or Hartmann Shack wavefront sensor SHWFS is an optical instrument used for characterizing an imaging system 1 2 It is a wavefront sensor commonly used in adaptive optics systems It consists of an array of lenses called lenslets of the same focal length Each is focused onto a photon sensor typically a CCD array or CMOS array 3 or quad cell 4 If the sensor is placed at the geometric focal plane of the lenslet 5 and is uniformly illuminated 6 then the integrated gradient of the wavefront across the lenslet is proportional to the displacement of the centroid Consequently any phase aberration can be approximated by a set of discrete tilts By sampling the wavefront with an array of lenslets all of these local tilts can be measured and the whole wavefront reconstructed Since only tilts are measured the Shack Hartmann cannot detect discontinuous steps in the wavefront Shack Hartmann system in clinical optics Laser creates a virtual light source in the retina The lenslet array creates spots in the sensor according to the wavefront coming out of the eye Inverse of the Shack Hartmann system in clinical optics A set of patterns is displayed on the screen the user aligns overlaps them in a single image pressing buttons A schematic illustration of a SHWFS Operations of a single lenslet in a SHWFS The design of this sensor improves upon an array of holes in a mask that had been developed in 1904 by Johannes Franz Hartmann as a means of tracing individual rays of light through the optical system of a large telescope thereby testing the quality of the image 2 In the late 1960s Roland Shack and Ben Platt modified the Hartmann screen by replacing the apertures in an opaque screen by an array of lenslets 7 1 The terminology as proposed by Shack and Platt was Hartmann screen The fundamental principle seems to be documented even before Huygens by the Jesuit philosopher Christopher Scheiner in Austria 8 Shack Hartmann sensors are used in astronomy to measure telescopes and in medicine to characterize eyes for corneal treatment of complex refractive errors 9 10 Recently Pamplona et al 11 developed and patented 12 an inverse of the Shack Hartmann system to measure one s eye lens aberrations While Shack Hartmann sensors measure the localized slope of the wavefront error using spot displacement in the sensor plane Pamplona et al replace the sensor plane with a high resolution visual display e g a mobile phone screen that displays spots that the user views through a lenslet array The user then manually shifts the displayed spots i e the generated wavefront until the spots align The magnitude of this shift provides data to estimate the first order parameters such as radius of curvature and hence error due to defocus and spherical aberration References edit a b Shack R V 1971 Smith F Dow ed Production and use of a lenticular Hartmann screen Journal of the Optical Society of America Oral presentation Ramada Inn Tucson Arizona 61 5 656 a b Hartmann J 1904 Objektivuntersuchungen Zeitschrift fur Instrumentenkunde Berlin Verlag von Julius Springer 24 1 25 33 47 97 117 T Nirmaier G Pudasaini J Bille 2003 Very fast wave front measurements at the human eye with a custom CMOS based Hartmann Shack sensor Optics Express OSA 11 21 2704 2716 Bibcode 2003OExpr 11 2704N doi 10 1364 oe 11 002704 PMID 19471385 LP Salles DW de Lima Monteiro 2010 Designing the response of an optical quad cell as position sensitive detector IEEE Sensors Journal IEEE 10 2 286 293 Bibcode 2010ISenJ 10 286S doi 10 1109 jsen 2009 2033806 Akondi Vyas Dubra Alfredo August 2019 Accounting for focal shift in the Shack Hartmann wavefront sensor Optics Letters 44 17 4151 4154 doi 10 1364 OL 44 004151 PMC 7535119 PMID 31465350 Akondi Vyas Steven Samuel Dubra Alfredo August 2019 Centroid error due to non uniform lenslet illumination in the Shack Hartmann wavefront sensor Optics Letters 44 17 4167 4170 doi 10 1364 OL 44 004167 PMC 7535117 PMID 31465354 Platt Ben C Shack Ronald October 2001 History and Principles of Shack Hartmann Wavefront Sensing Journal of Refractive Surgery 17 5 S573 7 doi 10 3928 1081 597X 20010901 13 PMID 11583233 Scheiner Oculus sive fundamentum opticum Innsbruck 1619 E Moreno Barriuso amp R Navarro 2000 Laser ray tracing versus Hartmann Shack sensor for measuring optical aberrations in the human eye JOSA A Optical Society of America 17 6 974 985 Bibcode 2000JOSAA 17 974M doi 10 1364 JOSAA 17 000974 hdl 10261 61848 PMID 10850467 Thomas Kohnen amp Douglas D Koch 2006 Cataract and refractive surgery Volume 2 Springer p 55 ISBN 978 3 540 30795 2 Pamplona Vitor F Mohan Ankit Oliveira Manuel M Raskar Ramesh 2010 NETRA Interactive Display for Estimating Refractive Errors and Focal Range PDF ACM Transactions on Graphics 29 4 doi 10 1145 1778765 1778814 hdl 1721 1 80392 Archived from the original PDF on 2012 10 12 US patent 8783871 Pamplona Vitor Menezes de Oliveira Manuel amp Mohan Ankit et al Near eye tool for refractive assessment published 2013 01 31 issued 2014 07 22 assigned to Massachusetts Institute of Technology See also editOptical Telescope Element used this sensor in development of the James Webb Space Telescope Retrieved from https en wikipedia org w index php title Shack Hartmann wavefront sensor amp oldid 1049045350, wikipedia, wiki, book, books, library,
