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Smetanin IV, Shutov AV, Ustinovskii NN, Veliev PV, Zvorykin VD. A New Insight into High-Aspect-Ratio Channel Drilling in Translucent Dielectrics with a KrF Laser for Waveguide Applications. MATERIALS (BASEL, SWITZERLAND) 2022; 15:8347. [PMID: 36499843 PMCID: PMC9738459 DOI: 10.3390/ma15238347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 11/18/2022] [Accepted: 11/20/2022] [Indexed: 06/17/2023]
Abstract
A new insight into capillary channel formation with a high aspect ratio in the translucent matter by nanosecond UV laser pulses is discussed based on our experiments on KrF laser multi-pulse drilling of polymethyl methacrylate and K8 silica glass. The proposed mechanism includes self-consistent laser beam filamentation along a small UV light penetration depth caused by a local refraction index increase due to material densification by both UV and ablation pressure, followed by filamentation-assisted ablation. A similar mechanism was shown to be realized in highly transparent media, i.e., KU-1 glass with a multiphoton absorption switched on instead of linear absorption. Waveguide laser beam propagation in long capillary channels was considered for direct electron acceleration by high-power laser pulses and nonlinear compression of excimer laser pulses into the picosecond range.
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Haber-Olguin A, Polania-Baron EJ, Trujillo-Trujillo F, Graue Hernandez EO. Thermographic Behavior of the Cornea During Treatment With Two Excimer Laser Platforms. Transl Vis Sci Technol 2021; 10:27. [PMID: 34427627 PMCID: PMC8399240 DOI: 10.1167/tvst.10.9.27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Purpose To investigate the temperature of the cornea during treatment with the excimer laser using two platforms, Nidek EC-5000 and Schwind Amaris 750S. Methods A prospective case series study was conducted in a reference center in Mexico City including patients aged 18 years or older who had any type of ametropia and underwent excimer laser refractive surgery. The patients had measurements of corneal temperature with an infrared camera before, during, and after ablation treatment. Results of prior corneal surface temperature, temperatures during excimer laser surgery, and delta temperature for each platform were analyzed and compared. Results A total of 107 eyes were analyzed. Mean baseline temperature was 32.7 ± 1.03°C for the Nidek group and 31.5 ± 1.4°C for the Amaris group. Mean maximum temperature was 39.94 ± 1.3°C for the Nidek group and 35.6 ± 1.5 °C for the Amaris group. Delta temperature was higher in the Nidek group than in the Amaris group. There were statistically significant associations between treated micrometers, treated diopters, and time in the Nidek group and no such associations in the Amaris group. Conclusions The different excimer laser devices used and the variety in the optical design, together with different software ablation algorithms, resulted in different levels of thermal loading; peak temperature rose in all measurements. Eyes treated with Nidek reached temperatures that doubled those found with Amaris. Translational Relevance The correlation between Delta of temperature with defocus, depth, and treatment time is different regarding excimer laser generation.
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Affiliation(s)
- Alberto Haber-Olguin
- Department of Cornea, External Disease, and Refractive Surgery, Instituto de Oftalmología "Conde de Valenciana," Mexico City, Mexico.,Aris Vision Institute, Mexico City, Mexico
| | - Eduardo J Polania-Baron
- Department of Cornea, External Disease, and Refractive Surgery, Instituto de Oftalmología "Conde de Valenciana," Mexico City, Mexico
| | | | - Enrique O Graue Hernandez
- Department of Cornea, External Disease, and Refractive Surgery, Instituto de Oftalmología "Conde de Valenciana," Mexico City, Mexico
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Bednarczyk S, Geoffray I, Perron G, Legaie O, Baclet P. Excimer Laser Ablation of 1D, 2D and Double Faces Sinusoidal Profiles on A-C:H (Amorphous Hydrogenated Carbon), Brominated Polystyrene and Polyimide Polymers Foils. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst49-813] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
| | | | - G. Perron
- CEA de Valduc, Is-sur-Tille, France, 21120
| | - O. Legaie
- CEA de Valduc, Is-sur-Tille, France, 21120
| | - Ph. Baclet
- CEA de Valduc, Is-sur-Tille, France, 21120
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Molecular-level removal of proteinaceous contamination from model surfaces and biomedical device materials by air plasma treatment. J Hosp Infect 2010; 76:234-42. [DOI: 10.1016/j.jhin.2010.07.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 07/02/2010] [Indexed: 11/17/2022]
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Carr JD, Hersh PS. Excimer Laser Technology: Key Concepts for the Ophthalmologist. Semin Ophthalmol 2009. [DOI: 10.3109/08820539609063814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Maldonado MJ, Nieto JC, Piñero DP. Advances in technologies for laser-assisted in situ keratomileusis (LASIK) surgery. Expert Rev Med Devices 2008; 5:209-29. [PMID: 18331182 DOI: 10.1586/17434440.5.2.209] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Laser-assisted in situ keratomileusis (LASIK) has become the most widely used form of refractive surgery today. The objective of this surgical technique is to modify the anterior corneal shape by ablating tissue from the stroma by means of the excimer laser after creating a hinged corneal flap. This way, we are able to change the refractive status of the patient, providing better unaided vision. Continuous improvements in the original technique have made the surgical procedure safer, more accurate and repeatable. These progressions are due to the development of novel technologies that are the responsible for new surgical instrumentation, which makes the surgical procedure easier for the surgeon, and better excimer laser ablation algorithms, which increase the optical quality of the ablation and thus the safety of the vision correction procedure. This article aims to describe the more relevant advances in LASIK that have played an important role in the spread and popularity of this technique.
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Affiliation(s)
- Miguel J Maldonado
- Department of Ophthalmology, Clínica Universitaria, University of Navarra, Avda Pio XII, 36, 31080, Pamplona, Spain.
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Prasad M, Conforti PF, Garrison BJ. Coupled molecular dynamics-Monte Carlo model to study the role of chemical processes during laser ablation of polymeric materials. J Chem Phys 2007; 127:084705. [PMID: 17764282 DOI: 10.1063/1.2754681] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The coarse grained chemical reaction model is enhanced to build a molecular dynamics (MD) simulation framework with an embedded Monte Carlo (MC) based reaction scheme. The MC scheme utilizes predetermined reaction chemistry, energetics, and rate kinetics of materials to incorporate chemical reactions occurring in a substrate into the MD simulation. The kinetics information is utilized to set the probabilities for the types of reactions to perform based on radical survival times and reaction rates. Implementing a reaction involves changing the reactants species types which alters their interaction potentials and thus produces the required energy change. We discuss the application of this method to study the initiation of ultraviolet laser ablation in poly(methyl methacrylate). The use of this scheme enables the modeling of all possible photoexcitation pathways in the polymer. It also permits a direct study of the role of thermal, mechanical, and chemical processes that can set off ablation. We demonstrate that the role of laser induced heating, thermomechanical stresses, pressure wave formation and relaxation, and thermochemical decomposition of the polymer substrate can be investigated directly by suitably choosing the potential energy and chemical reaction energy landscape. The results highlight the usefulness of such a modeling approach by showing that various processes in polymer ablation are intricately linked leading to the transformation of the substrate and its ejection. The method, in principle, can be utilized to study systems where chemical reactions are expected to play a dominant role or interact strongly with other physical processes.
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Affiliation(s)
- Manish Prasad
- Department of Chemistry, 104 Chemistry Building, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Spyratou E, Makropoulou M, Serafetinides AA. Study of visible and mid-infrared laser ablation mechanism of PMMA and intraocular lenses: experimental and theoretical results. Lasers Med Sci 2007; 23:179-88. [PMID: 17610104 DOI: 10.1007/s10103-007-0468-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Accepted: 05/02/2007] [Indexed: 10/23/2022]
Abstract
Laser-polymer interactions have attracted extensive attention both for understanding the inherent basic ablation mechanism and for development of tissue simulators in several biomedical laser applications such as in human ophthalmology. Ablation experiments were performed on polymethylmethacrylate used as cornea tissue simulator and PMMA intraocular lenses. The polymer-ablation mechanism was examined with two different wavelengths and pulse durations. The experiments were conducted with Nd:YAG and Er:YAG solid-state lasers, and the ablation rates were simulated by a mathematical model in each case. Furthermore, to investigate the role of tissue hydration during laser ablation, we performed a set of experiments in which Er:YAG laser ablation of hydrophilic acrylic intraocular lenses, with different H(2)O and D(2)O concentrations, was studied. The hydrophilic acrylic lenses with the higher concentration of H(2)O gave the most satisfactory results regarding both the ablation efficiency and the quality of the ablated craters.
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Affiliation(s)
- E Spyratou
- Department of Physics, School of Applied Mathematical and Physical Sciences, National Technical University of Athens, Zografou Campus, Athens 15780, Greece.
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Affiliation(s)
- Alfred Vogel
- Medical Laser Center Lübeck, Peter-Monnik-Weg 4, D-23562 Lübeck, Germany.
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Bityurin N, Luk'yanchuk BS, Hong MH, Chong TC. Models for laser ablation of polymers. Chem Rev 2003; 103:519-52. [PMID: 12580641 DOI: 10.1021/cr010426b] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- N Bityurin
- Institute of Applied Physics Russian Academy of Sciences, 603950, Nizhnii Novgorod, Russia.
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Abstract
BACKGROUND Water content of the corneal stroma may influence excimer laser ablation and may therefore affect residual refractive error following laser in situ keratomileusis. This study reports associations between water content of hydrogel materials and laser ablation depth. METHODS Hydrated (n = 4) and dehydrated (n = 4) hydrogel buttons of 38%, 45%, 55% and 69% water content were ablated with the Nidek EC-5000 ArF 193 nm excimer laser, set to deliver a -6.00 DS curvature. Central curvature, optical quality and water content were measured before and after ablation. Hydrated buttons were rehydrated postablation and prior to measurement, to eliminate the effect of water removal during the procedure. The ablation depth per pulse was calculated. RESULTS The average ablation rate for fully hydrated buttons was 0.51 +/- 0.17 microm. The ablation rate for hydrated materials (dry component ablation) reduced with increasing water content (P < 0.001). Dry hydrogel materials (0% water content) had an average ablation rate of 0.23 +/- 0.06 microm per pulse. CONCLUSIONS For a constant laser energy output, lower water content materials ablated to a greater extent than higher water content materials. This model provides a simple way to assess the effect of water content and dehydration on myopic laser in situ keratomileusis.
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Affiliation(s)
- Mark H Feltham
- Cooperative Research Centrefor Eye Research and Technology, University of New South Wales, Kensington, New South Wales, Australia.
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Nahen K, Vogel A. Plume dynamics and shielding by the ablation plume during Er:YAG laser ablation. JOURNAL OF BIOMEDICAL OPTICS 2002; 7:165-178. [PMID: 11966301 DOI: 10.1117/1.1463047] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2001] [Revised: 11/19/2001] [Accepted: 11/19/2001] [Indexed: 05/23/2023]
Abstract
Free-running Er:YAG lasers are used for precise tissue ablation in various clinical applications. The ablated material is ejected into the direction perpendicular to the tissue surface. We investigated the influence of shielding by the ablation plume on the energy deposition into an irradiated sample because it influences the ablation dynamics and the amount of material ablated. The investigations were performed using an Er:YAG laser with a pulse duration of 200 micros for the ablation of gelatin with different water contents, skin, and water. Laser flash photography combined with a dark field Schlieren technique was used to visualize gaseous and particulate ablation products, and to measure the distance traveled by the ablating laser beam through the ablation plume at various times after the beginning of the laser pulse. The temporal evolution of the transmission through the ablation plume was probed using a second free running Er:YAG laser beam directed parallel to the sample's surface. The ablation dynamics was found to consist of a vaporization phase followed by material ejection. The observation of droplet ejection during water ablation provided evidence that a phase explosion is the driving mechanism for material ejection. The laser light transmission was only slightly reduced by the vapor plume, but decreased by 25%-50% when the ejected material passed the probe beam. At radiant exposures approximately 10 times above the ablation threshold, the laser energy deposited into the sample amounted to only 61% of the incident energy for gelatin samples with 90% water content and to 86% for skin samples. For free-running Er:YAG laser pulses shielding must therefore be considered in modeling the ablation dynamics and determining the dosage for clinical applications.
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Affiliation(s)
- Kester Nahen
- Medical Laser Center Lübeck, Peter-Monnik-Weg 4, D-23562 Lübeck, Germany
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Belau L, Ben-Eliahu Y, Hecht I, Kop G, Haas Y, Welner S. Laser-Induced Dissociation of an Energetic Polymer: A Spectroscopic Study of the Gaseous Products. J Phys Chem B 2000. [DOI: 10.1021/jp001095u] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- L. Belau
- Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, and Armament Development Authority, POB 2250, Haifa, Israel
| | - Y. Ben-Eliahu
- Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, and Armament Development Authority, POB 2250, Haifa, Israel
| | - I. Hecht
- Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, and Armament Development Authority, POB 2250, Haifa, Israel
| | - G. Kop
- Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, and Armament Development Authority, POB 2250, Haifa, Israel
| | - Y. Haas
- Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, and Armament Development Authority, POB 2250, Haifa, Israel
| | - S. Welner
- Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, and Armament Development Authority, POB 2250, Haifa, Israel
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Haas Y, Ben-Eliahu Y, Welner S. Pulsed Laser Induced Decomposition of Energetic Polymers: Comparison of ultraviolet (355 nm) and infrared (9.3 ?m) initiation. PROPELLANTS EXPLOSIVES PYROTECHNICS 1996. [DOI: 10.1002/prep.19960210509] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Xiang Zhang, Grigoropoulos C, Krajnovich D, Tam A. Excimer laser projection micromachining of polyimide thin films annealed at different temperatures. ACTA ACUST UNITED AC 1996. [DOI: 10.1109/3476.558873] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Kapur R, Spargo BJ, Chen MS, Calvert JM, Rudolph AS. Fabrication and selective surface modification of 3-dimensionally textured biomedical polymers from etched silicon substrates. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 1996; 33:205-16. [PMID: 8953387 DOI: 10.1002/(sici)1097-4636(199624)33:4<205::aid-jbm1>3.0.co;2-t] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A new method is described for producing biomedically relevant polymers with precisely defined micron scale surface texture in the x, y, and z planes. Patterned Si templates were fabricated using photolithography to create a relief pattern in photoresist with lateral dimensions as small as 1 micron. Electroless Ni was selectively deposited in the trenches of the patterned substrate. The Ni served as a resilient mask for transferring the patterns onto the Si substrate to depths of up to 8.5 microns by anisotropic reactive ion etching with a fluorine-based plasma. The 3-dimensional (3-D) textured silicon substrates were used as robust, reusable molds for pattern transfer onto poly (dimethyl siloxane), low density poly (ethylene), poly (L-lactide), and poly (glycolide) by either casting or injection molding. The fidelity of the pattern transfer from the silicon substrates to the polymers was 90 to 95% in all three planes for all polymers for more than 60 transfers from a single wafer, as determined by scanning electron microscopy and atomic force microscopy. Further, the 3-D textured polymers were selectively modified to coat proteins either in the trenches or on the mesas by capillary modification or selective coating techniques. These selectively patterned 3-D polymer substrates may be useful for a variety of biomaterial applications.
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Affiliation(s)
- R Kapur
- Department of Biochemistry, Georgetown University, Washington, District of Columbia, USA.
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Nakayama Y, Matsuda T. Surface microarchitectural design in biomedical applications: preparation of microporous polymer surfaces by an excimer laser ablation technique. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 1995; 29:1295-301. [PMID: 8557732 DOI: 10.1002/jbm.820291017] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In this report we demonstrate a microprocessing method to prepare microporous polymer films by an excimer laser ablation technique, which may enable the fabrication of functional biomedical devices such as advanced artificial organs. The irradiation of a KrF excimer laser pulses (wave-length 248 nm; fluence 1 J/cm2 pulse) onto several polymer films was achieved by passing a laser pulse through an optical microscope, resulting in the formation of an etched pit on the irradiated surface due to ablative photodecomposition. The number of pulses and the micropositioning of the irradiation were precisely controlled by a computer-aided control unit. Minimal ablation was observed for polyethylene with very small absorption coefficient (alpha) at 248 nm. For polymers which absorbed the laser photons, the etch depth increased linearly with number of pulses. The etch depth per pulse decreased with an increase in alpha values. An excellent structural quality, with micron-order precision of an etched pit, was found for those polymers with larger alpha values, such as polyimide, segmented polyurethane, and polycarbonate.
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Affiliation(s)
- Y Nakayama
- Department of Bioengineering, National Cardiovascular Center Research Institute, Osaka, Japan
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Abstract
This article reviews the principle uses of ophthalmic lasers, providing historical background with an emphasis on new applications and areas of investigation. Ophthalmic photocoagulation was the first medical laser application and has restored or maintained vision in millions of people. More recently, photodisruption and, increasingly, ablation have gained prominence for treating a wide range of ocular pathology. The unique properties of lasers have also been harnessed for diagnostic purposes, with optical coherence tomography representing a significant improvement over existing imaging methods. Many ophthalmic applications of lasers have been developed, but the field is a dynamic one which continues to evolve along with laser technology itself.
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Affiliation(s)
- J M Krauss
- New England Eye Center, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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Takacs G, Vukanovic V, Tracy D, Chen J, Egitto F, Matienzo L, Emmi F. Photoetching and modification of organic polymer surfaces with vacuum UV radiation. Polym Degrad Stab 1993. [DOI: 10.1016/0141-3910(93)90193-m] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Vernon CF, Klauber C, van Saarloos PP, Chirila TV. Interaction between Poly(2- hydroxyethyl methacrylate) and High Energy Excimer Laser Radiation. POLYM INT 1992. [DOI: 10.1002/pi.4990270308] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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D'couto GC, Babu SV, Egitto FD, Davis CR. A Comparative Study of the Photoablation of Polyimide-Doped Poly(Tetrafluoroethylene) at 308 NM and 248 NM. ACTA ACUST UNITED AC 1992. [DOI: 10.1557/proc-285-157] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTExperimental data on the 248 nm and 308 nm wavelength excimer laser ablation of poly(tetrafluoroethylene) (PTFE) doped with polyimide (PI) are reported for a range of fluences and dopant concentrations. Threshold fluences were determined and correlated with the dopant concentrations. The threshold fluences and the limiting etch rates measured at high fluences decreased with increasing dopant concentration and there is a minimum absorption coefficient below which there is no ablation at both the wavelengths. The etch rates have been modeled using a two parameter Arrhenius thermal model to describe the etching process.
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Van Saarloos PP, Constable IJ. Bovine Corneal Stroma Ablation Rate With 193-nm Excimer Laser Radiation: Quantitative Measurement. J Refract Surg 1990. [DOI: 10.3928/1081-597x-19901101-08] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Otis CE. Detection of neutral products formed during excimer laser ablation of polyimide by UV and VUV laser photoionization/mass spectrometry. ACTA ACUST UNITED AC 1989. [DOI: 10.1007/bf00325349] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Creasy WR, Brenna J. Large carbon cluster ion formation by laser ablation of polyimide and graphite. Chem Phys 1988. [DOI: 10.1016/0301-0104(88)85053-5] [Citation(s) in RCA: 95] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Clarke RH, Nakagawa K, Isner JM. Comparison of free radicals produced by laser and ultrasound ablation of cardiovascular tissue. Photochem Photobiol 1988; 48:205-8. [PMID: 2851843 DOI: 10.1111/j.1751-1097.1988.tb02808.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Clarke RH, Isner JM, Gauthier T, Nakagawa K, Cerio F, Hanlon E, Gaffney E, Rouse E, DeJesus S. Spectroscopic characterization of cardiovascular tissue. Lasers Surg Med Suppl 1988; 8:45-59. [PMID: 3280930 DOI: 10.1002/lsm.1900080110] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We present results of a series of laser spectroscopic measurements on in vitro samples of cardiovascular tissue. These include laser Raman scattering, Fourier transform infrared, plasma emission and fluorescence, and electron paramagnetic resonance spectroscopy. The results of these spectroscopic measurements are discussed in terms of their implications for the field of laser angioplasty.
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Affiliation(s)
- R H Clarke
- Department of Chemistry, Boston University, MA 02215
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Clarke RH, Nakagawa K, Isner JM. The production of short-lived free radicals accompanying laser photoablation of cardiovascular tissue. Free Radic Biol Med 1988; 4:209-13. [PMID: 2834272 DOI: 10.1016/0891-5849(88)90041-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Using the method of spin trapping and electron paramagnetic resonance, free radicals have been detected accompanying laser ablation of cardiovascular tissue. Radicals were detected using both visible and ultraviolet laser energy from argon-ion and excimer laser sources. The results are discussed in terms of the relative efficiency of the laser wavelengths to produce free radicals and a comparison of the types of radicals produced by the action of pulsed versus cw laser energy.
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Affiliation(s)
- R H Clarke
- Department of Chemistry, Boston University, MA 02215
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Morelli J, Kibbi AG, Farinelli W, Boll J, Tan OT. Ultraviolet excimer laser ablation: the effect of wavelength and repetition rate on in vivo guinea pig skin. J Invest Dermatol 1987; 88:769-73. [PMID: 3585061 DOI: 10.1111/1523-1747.ep12470471] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Multiple dermatologic conditions that are currently treated with traditional cold-knife surgery are amenable to laser therapy. The ideal surgical treatment would be precise and total removal of abnormal tissue with maximal sparing of remaining structures. The ultraviolet (UV) excimer laser is capable of such precise tissue removal due to the penetration depth of 193 nm and 248 nm irradiation of 1 micron per pulse. This type of ablative tissue removal requires a high repetition rate for efficient lesional destruction. Excimer laser radiation at 193 nm is capable of high repetition rates, which are necessary while 248 nm radiation causes increasing nonspecific thermal injury as the laser repetition rate is increased.
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Clarke RH, Isner JM, Donaldson RF, Jones G. Gas chromatographic-light microscopic correlative analysis of excimer laser photoablation of cardiovascular tissues: evidence for a thermal mechanism. Circ Res 1987; 60:429-37. [PMID: 3581450 DOI: 10.1161/01.res.60.3.429] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The present series of experiments used gas chromatography to identify vapor-phase photoproducts liberated during excimer laser irradiation of cardiovascular tissues in air and blood. In air, laser beams produced from ArF (193 nm) and XeF (351 nm) excimer laser gas mixtures were delivered to samples of myocardium and atherosclerotic coronary arterial segments through the wall of a quartz cell, using 8-40 mJ/pulse. In blood, 351 nm were delivered via an optical fiber, using 14 mJ/pulse. When the experiments were performed using an air-tissue interface, the dominant photoproducts identified in order of elution from the gas chromatographic column were methane, acetylene, ethylene, ethane, propyne, allene, propylene, propane, and butene. When a fiberoptic was used to accomplish 351-nm excimer laser tissue ablation in a blood field, a similar gas chromatographic spectral distribution was observed. These vapor-phase photoproducts are indistinguishable from those observed following continuous wave laser irradiation or flame torching of cardiovascular tissues. Thus, despite the fact that excimer laser ablation of cardiovascular tissues is characterized by the absence of signs of thermal injury, the results of these experiments suggest that the predominant mechanism of excimer ablation is, like continuous-wave laser irradiation, a thermal process.
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Srinivasan R, Dyer PE, Braren B. Far-ultraviolet laser ablation of the cornea: photoacoustic studies. Lasers Surg Med 1987; 6:514-9. [PMID: 3573923 DOI: 10.1002/lsm.1900060606] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Wide bandwidth piezoelectric transducers made of thin (9 microns) polyvinylidene fluoride film have been used to make time-resolved measurements of the stress-wave generated by far-ultraviolet (193 nm) laser ablation in corneal tissue in vitro. At high fluence (approximately 250 mJ/cm2), ablation commences within 10 ns (+/- 5 ns) of the laser pulse and generates short acoustic impulses (approximately 30 ns). The time profile of the ablation, when coupled to the energy requirements for ablation from earlier work, allows the estimation of a temperature and a half-life for the thermal decomposition of the collagen in cornea. These values do not support a photothermal mechanism for the ablation under the experimental conditions.
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Abstract
When pulsed, ultraviolet laser radiation falls on the surface of an organic polymer or biological tissue, the material at the surface is spontaneously etched away to a depth of 0.1 to several micrometers. In the process, the depth of etching is controlled by the width of the pulse and the fluence of the laser, and there is no detectable thermal damage to the substrate. The material that is removed by etching consists of products ranging from atoms to small fragments of the polymer. They are ejected at supersonic velocities. This dry photoetching technique is useful in patterning polymer films. It is also under serious investigation in several areas in surgery.
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Abstract
Principles of laser-tissue interactions in the eye are reviewed. Corneal structure and function are summarized, with particular regard for features related to laser treatment. A summary of argon and carbon dioxide laser techniques in the cornea is presented, followed by a review of studies on corneal response to ultraviolet radiation. A detailed description is then given of the characteristics of excimer laser tissue ablation. Potential applications of this process in corneal and keratorefractive surgery are reviewed.
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