Scanning photorefractive keratectomy at 213 nm

PMMA ablations

Fabrice Manns, Pascal Rol, Martin Wosnitza, Patrick Maine, Jean-Marie A Parel

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

Purpose: In scanning photorefractive keratectomy, the corneal surface is reshaped by laser ablation with a scanning beam for the correction of myopia or astigmatism. A precise knowledge of the volume of corneal tissue removed by each laser pulse is necessary to be able to develop accurate ablation algorithms for scanning photorefractive keratectomy. The purpose of this study was to measure the ablation per pulse created on PMMA surfaces with a Q-switched frequency-quintupled Nd:YAG laser emitting at 213 nm. Methods: A frequency-quintupled Nd:YAG laser emitting at 213 nm with a pulse duration of 5 ns and a pulse energy of 1.2 to 1.5 mJ was used. The laser beam was focused on the surface of PMMA blocks and ablation craters were produced with 10, 50 and 100 pulses. The shape of the ablation craters was measured with an optical profilometer and compared with the beam profile measured with a laser beam diagnostic system. Results: The beam intensity distribution in the near-field consisted of two quasi-Gaussian peaks. The ablation craters contained two peaks. Assuming a Gaussian intensity distribution, the ablation per pulse in PMMA at 213 nm can be modeled by a parabolic function. Conclusions: Optical profilometry can be used to accurately measure the ablation per pulse and evaluate the homogeneity of the beam.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
PublisherSociety of Photo-Optical Instrumentation Engineers
Pages154-159
Number of pages6
Volume3591
StatePublished - 1999
EventProceedings of the 1999 Ophthalmic Technologies IX - San Jose, CA, USA
Duration: Jan 23 1999Jan 25 1999

Other

OtherProceedings of the 1999 Ophthalmic Technologies IX
CitySan Jose, CA, USA
Period1/23/991/25/99

Fingerprint

Ablation
ablation
Scanning
scanning
pulses
craters
Laser beams
YAG lasers
Laser pulses
myopia
laser beams
profilometers
Profilometry
astigmatism
Lasers
Laser ablation
laser ablation
homogeneity
near fields
pulse duration

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

Cite this

Manns, F., Rol, P., Wosnitza, M., Maine, P., & Parel, J-M. A. (1999). Scanning photorefractive keratectomy at 213 nm: PMMA ablations. In Proceedings of SPIE - The International Society for Optical Engineering (Vol. 3591, pp. 154-159). Society of Photo-Optical Instrumentation Engineers.

Scanning photorefractive keratectomy at 213 nm : PMMA ablations. / Manns, Fabrice; Rol, Pascal; Wosnitza, Martin; Maine, Patrick; Parel, Jean-Marie A.

Proceedings of SPIE - The International Society for Optical Engineering. Vol. 3591 Society of Photo-Optical Instrumentation Engineers, 1999. p. 154-159.

Research output: Chapter in Book/Report/Conference proceedingChapter

Manns, F, Rol, P, Wosnitza, M, Maine, P & Parel, J-MA 1999, Scanning photorefractive keratectomy at 213 nm: PMMA ablations. in Proceedings of SPIE - The International Society for Optical Engineering. vol. 3591, Society of Photo-Optical Instrumentation Engineers, pp. 154-159, Proceedings of the 1999 Ophthalmic Technologies IX, San Jose, CA, USA, 1/23/99.
Manns F, Rol P, Wosnitza M, Maine P, Parel J-MA. Scanning photorefractive keratectomy at 213 nm: PMMA ablations. In Proceedings of SPIE - The International Society for Optical Engineering. Vol. 3591. Society of Photo-Optical Instrumentation Engineers. 1999. p. 154-159
Manns, Fabrice ; Rol, Pascal ; Wosnitza, Martin ; Maine, Patrick ; Parel, Jean-Marie A. / Scanning photorefractive keratectomy at 213 nm : PMMA ablations. Proceedings of SPIE - The International Society for Optical Engineering. Vol. 3591 Society of Photo-Optical Instrumentation Engineers, 1999. pp. 154-159
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abstract = "Purpose: In scanning photorefractive keratectomy, the corneal surface is reshaped by laser ablation with a scanning beam for the correction of myopia or astigmatism. A precise knowledge of the volume of corneal tissue removed by each laser pulse is necessary to be able to develop accurate ablation algorithms for scanning photorefractive keratectomy. The purpose of this study was to measure the ablation per pulse created on PMMA surfaces with a Q-switched frequency-quintupled Nd:YAG laser emitting at 213 nm. Methods: A frequency-quintupled Nd:YAG laser emitting at 213 nm with a pulse duration of 5 ns and a pulse energy of 1.2 to 1.5 mJ was used. The laser beam was focused on the surface of PMMA blocks and ablation craters were produced with 10, 50 and 100 pulses. The shape of the ablation craters was measured with an optical profilometer and compared with the beam profile measured with a laser beam diagnostic system. Results: The beam intensity distribution in the near-field consisted of two quasi-Gaussian peaks. The ablation craters contained two peaks. Assuming a Gaussian intensity distribution, the ablation per pulse in PMMA at 213 nm can be modeled by a parabolic function. Conclusions: Optical profilometry can be used to accurately measure the ablation per pulse and evaluate the homogeneity of the beam.",
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