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High Pulse Energy, Narrow Linewidth 6.45 μm from an Optical Parametric Oscillator in BaGa4Se7 Crystal. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12136689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This paper presents a high pulse energy, narrow linewidth, mid-infrared (MIR) laser at 6.45 μm, based on a BaGa4Se7 (BGSe) crystal optical parametric oscillator (OPO) pumped by 1.064 μm laser. The maximum pulse energy at 6.45 μm was up to 1.23 mJ, with a pulse width of 24.3 ns and repetition rate of 10 Hz, corresponding to an optical–optical conversion efficiency of 2.1%, from pump light 1.064 μm to idler light 6.45 μm. The idler light linewidth was about 6.8 nm. Meanwhile, we accurately calculated the OPO phase-matching condition at BGSe crystal pumped by 1.064 μm laser, and a numerical simulation system was performed to analyze the input–output characteristics at 6.45 μm, as well as the effect of crystal length on the conversion efficiency. Good agreement was found between measurement and simulation. To the best of our knowledge, this is the highest pulse energy at 6.45 μm, with the narrowest linewidth for any all-solid-state MIR ns laser in BGSe-OPO pumped by simple 1.064 μm oscillator. This simple and compact 6.45 μm OPO system, with high pulse energy and narrow linewidth, can meet the requirements for tissue cutting and improve tissue ablation accuracy.
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Kim B, Kim DY. Enhanced Tissue Ablation Efficiency with a Mid-Infrared Nonlinear Frequency Conversion Laser System and Tissue Interaction Monitoring Using Optical Coherence Tomography. SENSORS (BASEL, SWITZERLAND) 2016; 16:E598. [PMID: 27128916 PMCID: PMC4883289 DOI: 10.3390/s16050598] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 04/08/2016] [Accepted: 04/21/2016] [Indexed: 12/21/2022]
Abstract
We report development of optical parametric oscillator (OPO)-based mid-infrared laser system that utilizes a periodically poled nonlinear crystal pumped by a near-infrared (NIR) laser. We obtained a mid-infrared average output of 8 W at an injection current of 20 A from a quasi-phase-matched OPO using an external cavity configuration. Laser tissue ablation efficiency is substantially affected by several parameters, including an optical fluence rate, wavelength of the laser source, and the optical properties of target tissue. Dimensions of wavelength and radiant exposure dependent tissue ablation are quantified using Fourier domain optical coherence tomography and the ablation efficiency was compared to a non-converted NIR laser system.
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Affiliation(s)
- Bongkyun Kim
- Beckman Laser Institute Korea, Dankook University, 119, Dandae-ro, Dongnam-gu, Cheonan-si, Chungnam 31116, Korea.
| | - Dae Yu Kim
- Beckman Laser Institute Korea, Dankook University, 119, Dandae-ro, Dongnam-gu, Cheonan-si, Chungnam 31116, Korea.
- Biomedical Engineering, College of Medicine, Dankook University, 119, Dandae-ro, Dongnam-gu, Cheonan-si, Chungnam 31116, Korea.
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Kozub J, Shen JH, Joos KM, Prasad R, Hutson MS. Optic nerve sheath fenestration using a Raman-shifted alexandrite laser. Lasers Surg Med 2016; 48:270-80. [PMID: 27020001 DOI: 10.1002/lsm.22456] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/19/2015] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND OBJECTIVE Optic nerve sheath fenestration is an established procedure for relief of potentially damaging overpressure on the optic nerve resulting from idiopathic intracranial hypertension. Prior work showed that a mid-IR free-electron laser could be delivered endoscopically and used to produce an effective fenestration. This study evaluates the efficacy of fenestration using a table-top mid-IR source based on a Raman-shifted alexandrite (RSA) laser. STUDY DESIGN/MATERIALS AND METHODS Porcine optic nerves were ablated using light from an RSA laser at wavelengths of 6.09, 6.27, and 6.43 μm and pulse energies up to 3 mJ using both free-space and endoscopic beam delivery through 250-μm I.D. hollow-glass waveguides. Waveguide transmission was characterized, ablation thresholds and etch rates were measured, and the efficacy of endoscopic fenestration was evaluated for ex vivo exposures using both optical coherence tomography and histological analysis. RESULTS Using endoscopic delivery, the RSA laser can effectively fenestrate porcine optic nerves. Performance was optimized at a wavelength of 6.09 μm and delivered pulse energies of 0.5-0.8 mJ (requiring 1.5-2.5 mJ to be incident on the waveguide). Under these conditions, the ablation threshold fluence was 0.8 ± 0.2 J/cm(2) , the ablation rate was 1-4 μm/pulse, and the margins of ablation craters showed little evidence of thermal or mechanical damage. Nonetheless, nominally identical exposures yielded highly variable ablation rates. This led to fenestrations that ranged from too deep to too shallow-either damaging the underlying optic nerve or requiring additional exposure to cut fully through the sheath. Of 48 excised nerves subjected to fenestration at 6.09 μm, 16 ex vivo fenestrations were judged as good, 23 as too deep, and 9 as too shallow. CONCLUSIONS Mid-IR pulses from the RSA laser, propagated through a flexible hollow waveguide, are capable of cutting through porcine optic nerve sheaths in surgically relevant times with reasonable accuracy and low collateral damage. This can be accomplished at wavelengths of 6.09 or 6.27 μm, with 6.09 μm slightly preferred. The depth of ex vivo fenestrations was difficult to control, but excised nerves lack a sufficient layer of cerebrospinal fluid that would provide an additional margin of safety in actual patients.
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Affiliation(s)
- John Kozub
- Department of Physics & Astronomy, Vanderbilt University, Nashville, 37235, Tennessee
| | - Jin H Shen
- Vanderbilt Eye Institute, Vanderbilt University, Nashville, 37232, Tennessee.,Vanderbilt Institute in Surgery and Engineering, Vanderbilt University, Nashville, 37235, Tennessee
| | - Karen M Joos
- Vanderbilt Eye Institute, Vanderbilt University, Nashville, 37232, Tennessee.,Vanderbilt Institute in Surgery and Engineering, Vanderbilt University, Nashville, 37235, Tennessee.,Vanderbilt Biophotonics Center, Vanderbilt University, Nashville, 37235, Tennessee
| | - Ratna Prasad
- Vanderbilt Eye Institute, Vanderbilt University, Nashville, 37232, Tennessee
| | - M Shane Hutson
- Department of Physics & Astronomy, Vanderbilt University, Nashville, 37235, Tennessee.,Vanderbilt Biophotonics Center, Vanderbilt University, Nashville, 37235, Tennessee.,Vanderbilt Institute for Integrative Biosystem Research & Education, Vanderbilt University, Nashville, 37235, Tennessee
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Kozub JA, Shen JH, Joos KM, Prasad R, Shane Hutson M. Efficacy and predictability of soft tissue ablation using a prototype Raman-shifted alexandrite laser. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:105004. [PMID: 26456553 PMCID: PMC4963468 DOI: 10.1117/1.jbo.20.10.105004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 08/28/2015] [Indexed: 06/05/2023]
Abstract
Previous research showed that mid-infrared free-electron lasers could reproducibly ablate soft tissue with little collateral damage. The potential for surgical applications motivated searches for alternative tabletop lasers providing thermally confined pulses in the 6- to-7-µm wavelength range with sufficient pulse energy, stability, and reliability. Here, we evaluate a prototype Raman-shifted alexandrite laser. We measure ablation thresholds, etch rates, and collateral damage in gelatin and cornea as a function of laser wavelength (6.09, 6.27, or 6.43 µm), pulse energy (up to 3 mJ/pulse), and spot diameter (100 to 600 µm). We find modest wavelength dependence for ablation thresholds and collateral damage, with the lowest thresholds and least damage for 6.09 µm. We find a strong spot-size dependence for all metrics. When the beam is tightly focused (~100-µm diameter), ablation requires more energy, is highly variable and less efficient, and can yield large zones of mechanical damage (for pulse energies>1 mJ). When the beam is softly focused (~300-µm diameter), ablation proceeded at surgically relevant etch rates, with reasonable reproducibility (5% to 12% within a single sample), and little collateral damage. With improvements in pulse-energy stability, this prototype laser may have significant potential for soft-tissue surgical applications.
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Affiliation(s)
- John A. Kozub
- Vanderbilt University, Department of Physics and Astronomy, 6301 Stevenson Center, Nashville, Tennessee 37235, United States
| | - Jin-H. Shen
- Vanderbilt University Medical Center, Department of Ophthalmology and Vanderbilt Eye Institute, 2311 Pierce Avenue, Nashville, Tennessee 37232, United States
| | - Karen M. Joos
- Vanderbilt University Medical Center, Department of Ophthalmology and Vanderbilt Eye Institute, 2311 Pierce Avenue, Nashville, Tennessee 37232, United States
| | - Ratna Prasad
- Vanderbilt University Medical Center, Department of Ophthalmology and Vanderbilt Eye Institute, 2311 Pierce Avenue, Nashville, Tennessee 37232, United States
| | - M. Shane Hutson
- Vanderbilt University, Department of Physics and Astronomy, 6301 Stevenson Center, Nashville, Tennessee 37235, United States
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Marcus GA, Schwettman HA. Rapid thermal equilibration of differentially heated protein and water in bovine corneal stroma. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:041913. [PMID: 22181181 DOI: 10.1103/physreve.84.041913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 08/09/2011] [Indexed: 05/31/2023]
Abstract
We measure and simulate the thermal response of bovine corneal stroma to a picosecond IR heating pulse. A thermal diffusion model is developed for this tissue based on the spatial distribution and properties of protein and water constituents in the stroma. In this idealized model, differentially heated protein and water constituents thermally equilibrate with a thermalization time of 515 ps. Using transient absorption spectroscopy for picosecond protein thermometry, a significantly faster thermalization time of 165 ps is measured. The implications of this faster than expected thermalization for the energy-partition model of short-pulse mid-IR tissue ablation are discussed.
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Affiliation(s)
- George Alexander Marcus
- Department of Physics and Astronomy, 1 College Circle, SUNY Geneseo, Geneseo, New York 14425, USA.
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Kozub J, Ivanov B, Jayasinghe A, Prasad R, Shen J, Klosner M, Heller D, Mendenhall M, Piston DW, Joos K, Hutson MS. Raman-shifted alexandrite laser for soft tissue ablation in the 6- to 7-µm wavelength range. BIOMEDICAL OPTICS EXPRESS 2011; 2:1275-81. [PMID: 21559139 PMCID: PMC3087584 DOI: 10.1364/boe.2.001275] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Revised: 04/10/2011] [Accepted: 04/14/2011] [Indexed: 05/16/2023]
Abstract
Prior work with free-electron lasers (FELs) showed that wavelengths in the 6- to 7-µm range could ablate soft tissues efficiently with little collateral damage; however, FELs proved too costly and too complex for widespread surgical use. Several alternative 6- to 7-µm laser systems have demonstrated the ability to cut soft tissues cleanly, but at rates that were much too low for surgical applications. Here, we present initial results with a Raman-shifted, pulsed alexandrite laser that is tunable from 6 to 7 µm and cuts soft tissues cleanly-approximately 15 µm of thermal damage surrounding ablation craters in cornea-and does so with volumetric ablation rates of 2-5 × 10(-3) mm(3)/s. These rates are comparable to those attained in prior successful surgical trials using the FEL for optic nerve sheath fenestration.
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Affiliation(s)
- John Kozub
- Department of Physics & Astronomy, Vanderbilt University, Nashville, TN 37235, USA
| | - Borislav Ivanov
- Department of Physics & Astronomy, Vanderbilt University, Nashville, TN 37235, USA
| | - Aroshan Jayasinghe
- Department of Physics & Astronomy, Vanderbilt University, Nashville, TN 37235, USA
| | - Ratna Prasad
- Vanderbilt Eye Institute, Vanderbilt University, Nashville, TN 37232, USA
| | - Jin Shen
- Vanderbilt Eye Institute, Vanderbilt University, Nashville, TN 37232, USA
| | - Marc Klosner
- Light Age, Inc., 500 Apgar Drive, Somerset, NJ 08873, USA
| | - Donald Heller
- Light Age, Inc., 500 Apgar Drive, Somerset, NJ 08873, USA
| | - Marcus Mendenhall
- Department of Physics & Astronomy, Vanderbilt University, Nashville, TN 37235, USA
| | - David W. Piston
- Department of Physics & Astronomy, Vanderbilt University, Nashville, TN 37235, USA
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, TN 37232, USA
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - Karen Joos
- Vanderbilt Eye Institute, Vanderbilt University, Nashville, TN 37232, USA
| | - M. Shane Hutson
- Department of Physics & Astronomy, Vanderbilt University, Nashville, TN 37235, USA
- Vanderbilt Institute for Integrative Biosystem Research & Education, Nashville, TN 37235, USA
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Hutson MS, Ivanov B, Jayasinghe A, Adunas G, Xiao Y, Guo M, Kozub J. Interplay of wavelength, fluence and spot-size in free-electron laser ablation of cornea. OPTICS EXPRESS 2009; 17:9840-9850. [PMID: 19506634 DOI: 10.1364/oe.17.009840] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Infrared free-electron lasers ablate tissue with high efficiency and low collateral damage when tuned to the 6-microm range. This wavelength-dependence has been hypothesized to arise from a multi-step process following differential absorption by tissue water and proteins. Here, we test this hypothesis at wavelengths for which cornea has matching overall absorption, but drastically different differential absorption. We measure etch depth, collateral damage and plume images and find that the hypothesis is not confirmed. We do find larger etch depths for larger spot sizes--an effect that can lead to an apparent wavelength dependence. Plume imaging at several wavelengths and spot sizes suggests that this effect is due to increased post-pulse ablation at larger spots.
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Affiliation(s)
- M Shane Hutson
- Department of Physics & Astronomy, Vanderbilt University, Nashville, TN 37235, USA.
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Wilmink GJ, Opalenik SR, Beckham JT, Mackanos MA, Nanney LB, Contag CH, Davidson JM, Jansen ED. In-vivo optical imaging of hsp70 expression to assess collateral tissue damage associated with infrared laser ablation of skin. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:054066. [PMID: 19021444 PMCID: PMC3840494 DOI: 10.1117/1.2992594] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Laser surgical ablation is achieved by selecting laser parameters that remove confined volumes of target tissue and cause minimal collateral damage. Previous studies have measured the effects of wavelength on ablation, but neglected to measure the cellular impact of ablation on cells outside the lethal zone. In this study, we use optical imaging in addition to conventional assessment techniques to evaluate lethal and sublethal collateral damage after ablative surgery with a free-electron laser (FEL). Heat shock protein (HSP) expression is used as a sensitive quantitative marker of sublethal damage in a transgenic mouse strain, with the hsp70 promoter driving luciferase and green fluorescent protein (GFP) expression (hsp70A1-L2G). To examine the wavelength dependence in the mid-IR, laser surgery is conducted on the hsp70A1-L2G mouse using wavelengths targeting water (OH stretch mode, 2.94 microm), protein (amide-II band, 6.45 microm), and both water and protein (amide-I band, 6.10 microm). For all wavelengths tested, the magnitude of hsp70 expression is dose-dependent and maximal 5 to 12 h after surgery. Tissues treated at 6.45 microm have approximately 4x higher hsp70 expression than 6.10 microm. Histology shows that under comparable fluences, tissue injury at the 2.94-microm wavelength was 2x and 3x deeper than 6.45 and 6.10 microm, respectively. The 6.10-microm wavelength generates the least amount of epidermal hyperplasia. Taken together, this data suggests that the 6.10-microm wavelength is a superior wavelength for laser ablation of skin.
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Affiliation(s)
- Gerald J Wilmink
- Vanderbilt University, Department of Biomedical Engineering, Nashville, Tennessee 37235, USA
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