Dr. Thomas Asshauer Profile

Dr. Thomas Asshauer

Head of Application Engineering

Area of Expertise:

Optical Engineering , Opthalmology , R&D Management , Medical Lasers , Physics

Websites:

Company Website

Publications (10)

Proceedings Article | 14 January 1998 Paper

Imaging of strain in a tissue phantom during pulsed holmium laser ablation

Didier Beghuin, Joseph Walsh, Guy Delacretaz, Thomas Asshauer

Proceedings Volume 3195, (1998) https://doi.org/10.1117/12.297898

KEYWORDS: Birefringence, Laser tissue interaction, Tissues, Pulsed laser operation, Holmium, Laser ablation, Tissue optics, Natural surfaces, Nd:YAG lasers, Polarimetry

Read Abstract +

Proceedings Article | 7 May 1996 Paper

Photothermal denaturation of egg white by pulsed holmium laser

Thomas Asshauer, Guy Delacretaz, Sohi Rastegar

Proceedings Volume 2681, (1996) https://doi.org/10.1117/12.239563

KEYWORDS: Pulsed laser operation, Holmium, Fiber lasers, Laser scattering, Light scattering, Thermal modeling, Tissues, Scattering, Laser processing, Picosecond phenomena

Read Abstract +

Proceedings Article | 10 January 1996 Paper

Holmium laser ablation of cartilage: effects of delivery fiber angle of incidence

Thomas Asshauer, Thorsten Oberthur, Thomas Jansen, Bruno Gerber, Guy Delacretaz

Proceedings Volume 2624, (1996) https://doi.org/10.1117/12.229537

KEYWORDS: Cartilage, Laser ablation, Pulsed laser operation, Tissues, Holmium, Fiber lasers, Laser tissue interaction, Natural surfaces, Liquids, Laser energy

Read Abstract +

Proceedings Article | 22 May 1995 Paper

Effect of Young's modulus on bubble formation and pressure waves during pulsed holmium ablation of tissue phantoms

E. Duco Jansen, Thomas Asshauer, Martin Frenz, Guy Delacretaz, Massoud Motamedi, Ashley Welch

Proceedings Volume 2391, (1995) https://doi.org/10.1117/12.209906

KEYWORDS: Pulsed laser operation, Tissues, Laser ablation, Q switched lasers, Q switching, Fiber lasers, Laser tissue interaction, Holmium, Photography, Tissue optics

Read Abstract +

Proceedings Article | 22 May 1995 Paper

Holmium laser ablation of cartilage: effects of cavitation bubbles

Thomas Asshauer, Thomas Jansen, Thorsten Oberthur, Guy Delacretaz, Bruno Gerber

Proceedings Volume 2391, (1995) https://doi.org/10.1117/12.209905

KEYWORDS: Cartilage, Laser ablation, Holmium, Fiber lasers, Cavitation, Pulsed laser operation, Laser energy, Laser tissue interaction, Tissues, Acoustics

Read Abstract +

Proceedings Article | 12 May 1995 Paper

Effect of pulse duration on photomechanical response of soft tissue during Ho:YAG laser ablation

E. Duco Jansen, Massoud Motamedi, T. Joshua Pfefer, Thomas Asshauer, Martin Frenz, Guy Delacretaz, George Abela, Ashley Welch

Proceedings Volume 2395, (1995) https://doi.org/10.1117/12.209071

KEYWORDS: Pulsed laser operation, Laser tissue interaction, Laser ablation, Tissues, Fiber lasers, Q switched lasers, Holmium, Q switching, Photography, Picosecond phenomena

Read Abstract +

Mechanical injury during pulsed holmium laser ablation of tissue is caused by rapid bubble expansion and collapse or by laser-induced pressure waves. In this study the effect of pulse duration on the photomechanical response of soft tissue during holmium:YAG laser ablation has been investigated. The dynamics of laser-induced bubble formation was documented in water and in transparent polyacrylamide tissue phantoms with a water concentration of 84%. Holmium:YAG laser radiation ((lambda) equals 2.12 micrometers ) was delivered in water or tissue phantoms via an optical fiber (200 or 400 micrometers ). The laser was operated in either the Q- switched mode ((tau) _p equals 500 ns, Q_p equals 14 +/- 1 mJ, 200 micrometers fiber, H_o equals 446 mJ/mm²) or the free-running mode ((tau) _p equals 100 - 1100 microsecond(s) , Q_p equals 200 +/- 5 mJ, 400 micrometers fiber, H_o equals 1592 mJ/mm²). Bubble formation was documented using a fast flash photography setup while simultaneously a PVDP needle hydrophone (40 ns risetime), recorded pressures. The effect of the pulse duration on the photomechanical response of soft biological tissue was evaluated by delivering 5 pulses of 800 mJ to the intimal side of porcine aorta in vitro, followed by histologic evaluation. It was observed that, as the pulse duration was increased the bubble shape changed from almost spherical for Q-switched pulses to a more elongated, cylindrical shape for the longer pulse durations. The bubble expansion velocity was larger for shorter pulse durations. A thermo- elastic expansion wave was measured only during Q-switched pulse delivery. All pulses that induced bubble formation generated pressure waves upon collapse of the bubble in water as well as in the gel. The amplitude of the pressure wave depended strongly on the size and geometry of the laser-induced bubble. The important findings of this study were (1) the magnitude of collapse pressure wave decreased as laser pulse duration increased, and (2) mechanical tissue damage is reduced significantly by using longer pulse durations (> 460 microsecond(s) , for the pulse energy used).

Proceedings Article | 18 January 1995 Paper

Acoustic transients in pulsed holmium laser ablation: effects of pulse duration

Thomas Asshauer, Guy Delacretaz, E. Duco Jansen, Ashley Welch, Martin Frenz

Proceedings Volume 2323, (1995) https://doi.org/10.1117/12.199189

KEYWORDS: Pulsed laser operation, Acoustics, Holmium, Cavitation, Tissues, Q switched lasers, Q switching, Picosecond phenomena, Laser ablation, Fiber lasers

Read Abstract +

Proceedings Article | 18 January 1995 Paper

Influence of pulse duration on erbium and holmium laser ablation under water

Michael Ith, Martin Frenz, Hans Pratisto, Heinz Weber, Hans Altermatt, Hans Staeubli, Thomas Asshauer, Guy Delacretaz, Rene-Paul Salathe, Bruno Gerber

Proceedings Volume 2323, (1995) https://doi.org/10.1117/12.199190

KEYWORDS: Pulsed laser operation, Holmium, Erbium lasers, Laser tissue interaction, Laser ablation, Laser cutting, Tissues, Erbium, Diodes, Fiber lasers

Read Abstract +

Proceedings Article | 17 August 1994 Paper

Acoustic transient generation in pulsed holmium laser ablation under water

Thomas Asshauer, Klaus Rink, Guy Delacretaz, Rene-Paul Salathe, Bruno Gerber, Martin Frenz, Hans Pratisto, Michael Ith, Valerio Romano, Heinz Weber

Proceedings Volume 2134, (1994) https://doi.org/10.1117/12.182961

KEYWORDS: Acoustics, Holmium, Laser ablation, Natural surfaces, Cavitation, Fiber lasers, Photography, Lamps, Nd:YAG lasers, Ferroelectric polymers

Read Abstract +

Proceedings Article | 17 August 1994 Paper

Transient photoacoustic effects induced in liquids by pulsed erbium lasers

Martin Frenz, Hans Pratisto, Michael Ith, Thomas Asshauer, Klaus Rink, Guy Delacretaz, Valerio Romano, Rene-Paul Salathe, Heinz Weber

Proceedings Volume 2134, (1994) https://doi.org/10.1117/12.182959

KEYWORDS: Erbium lasers, Liquids, Pulsed laser operation, Photoacoustic spectroscopy, Laser ablation, Medicine, Laser tissue interaction, Absorption, Explosives, Laser damage threshold

Read Abstract +

Showing 5 of 10 publications

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years