scholarly journals Femtosecond lasers for eye surgery applications: historical overview and modern low pulse energy concepts

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Thomas Asshauer ◽  
Catharina Latz ◽  
Alireza Mirshahi ◽  
Christian Rathjen
Keyword(s):  
Pulse Energy ◽  
Femtosecond Lasers ◽  
Laser System ◽  
Numerical Aperture ◽  
Optical Breakdown ◽  
Pulse Frequency ◽  
High Pulse Frequency ◽  
Fs Laser ◽  
High Pulse ◽  
Lens Surgery

Abstract This review provides an overview of the historical development and modern applications of femtosecond (fs) lasers in ophthalmology, with a focus on the optical concepts involved. fs-Laser technology is unique because it allows very precise cutting inside the eye through optically transparent tissue, without a need for any mechanical openings. fs-Lasers were historically first used for refractive cornea surgery, later also for therapeutic cornea procedures and lens surgery. Further new areas of ophthalmic application are under development. The latest laser system concept is low pulse energy and high pulse frequency: by using larger numerical aperture focusing optics, the pulse energy required for optical breakdown decreases, and athermal tissue cutting with minimal side effects is enabled.

scholarly journals Femtosecond-Laser Assisted Surgery of the Eye: Overview and Impact of the Low-Energy Concept

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 122
Author(s):  
Catharina Latz ◽  
Thomas Asshauer ◽  
Christian Rathjen ◽  
Alireza Mirshahi
Keyword(s):  
Surgical Techniques ◽  
Numerical Aperture ◽  
Optical Breakdown ◽  
Pulse Frequency ◽  
Low Energy ◽  
Human Cornea ◽  
Energy Concept ◽  
High Pulse Frequency ◽  
Fs Laser ◽  
High Pulse

This article provides an overview of both established and innovative applications of femtosecond (fs)-laser-assisted surgical techniques in ophthalmology. Fs-laser technology is unique because it allows cutting tissue at very high precision inside the eye. Fs lasers are mainly used for surgery of the human cornea and lens. New areas of application in ophthalmology are on the horizon. The latest improvement is the high pulse frequency, low-energy concept; by enlarging the numerical aperture of the focusing optics, the pulse energy threshold for optical breakdown decreases, and cutting with practically no side effects is enabled.

High-average-power and high-pulse-energy CEP-stable few-cycle pulses: Status of the ELI-ALPS HR2 laser system

2021 ◽  
Author(s):  
Steffen Hadrich ◽  
Evgeny Shestaev ◽  
Nico Walther ◽  
Tamas Nagy ◽  
Peter Simon ◽  
...  
Keyword(s):  
Pulse Energy ◽  
Laser System ◽  
Average Power ◽  
High Pulse Energy ◽  
High Average Power ◽  
High Pulse

scholarly journals A New Filter Concept for High Pulse-Frequency 3-Phase AFE Motor Drives

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2814
Author(s):  
Stefan Hoffmann ◽  
Matthias Bock ◽  
Eckart Hoene
Keyword(s):  
Pulse Frequency ◽  
Motor Drives ◽  
Common Mode ◽  
The Public ◽  
Electrical Potentials ◽  
Common Mode Voltage ◽  
High Pulse Frequency ◽  
Power Modules ◽  
High Pulse ◽  
The Difference

The size of back-to-back converters with active front end is significantly determined by the size of the passive filter components. This paper presents a new complete EMC filter concept for this type of converter system that is effective on the input and the output. This involves filtering the main common mode interferences from the grid and motor sides with a single CM choke. Since only the difference of the generated common mode voltage-time areas of both converters is absorbed by this component, the size of the required filter can be greatly reduced compared to conventional filter concepts. The concept is validated on a grid feeding inverter that can be connected to the public distribution network with an output power of 63 kW. The size reduction is demonstrated by means of a design example on a system with the same power and electrical requirements. It is elaborated why, applying the new filter concept, the impedance of the DC link potentials to ground and other electrical potentials should be as high as possible and therefore associated parasitic capacitances should be minimized. From this requirement, rules for the design of the power modules of PFC and motor converters for the application of this filter concept are derived.

scholarly journals A high-beam-quality, high-pulse-energy picosecond laser system for high precision ultra-remote laser ranging

2019 ◽  
Vol 64 (17) ◽  
pp. 1761-1762 ◽  
Author(s):  
Zhongwei Fan ◽  
Yutao Huang ◽  
Xiaochao Yan ◽  
Guangyan Guo ◽  
en Zh ◽  
...  
Keyword(s):  
High Precision ◽  
Pulse Energy ◽  
Beam Quality ◽  
Laser System ◽  
Picosecond Laser ◽  
Laser Ranging ◽  
High Pulse Energy ◽  
High Beam ◽  
High Pulse ◽  
High Beam Quality

scholarly journals High-pulse-energy passively Q-switched sub-nanosecond MOPA laser system operating at kHz level

2021 ◽  
Author(s):  
Yiping Zhou ◽  
XuDong Li ◽  
Haobo Xu ◽  
Renpeng Yan ◽  
Yugang Jiang ◽  
...  
Keyword(s):  
Pulse Energy ◽  
Laser System ◽  
High Pulse Energy ◽  
High Pulse ◽  
Mopa Laser ◽  
System Operating

All-Solid-State High Pulse Repetition Rate High Pulse Energy Single-Longitudinal-Mode MOPA Laser System with Solid-State Phase Conjugating Mirror

2010 ◽  
Vol 37 (12) ◽  
pp. 2949-2953
Author(s):  
赵智刚 Zhao Zhigang ◽  
崔玲玲 Cui Lingling ◽  
童立新 Tong Lixin ◽  
高清松 Gao Qingsong ◽  
唐淳 Tang Chun ◽  
...  
Keyword(s):  
Solid State ◽  
Pulse Energy ◽  
Repetition Rate ◽  
Pulse Repetition Rate ◽  
Laser System ◽  
Longitudinal Mode ◽  
High Pulse Energy ◽  
High Pulse Repetition Rate ◽  
High Pulse ◽  
Mopa Laser

Deletion of Gαq/11 or Gαs proteins in gonadotropes differentially affects gonadotropin production and secretion in mice

Endocrinology ◽  
2021 ◽  
Author(s):  
George A Stamatiades ◽  
Chirine Toufaily ◽  
Han Kyeol Kim ◽  
Xiang Zhou ◽  
Iain R Thompson ◽  
...  
Keyword(s):  
Hypogonadotropic Hypogonadism ◽  
Pulse Frequency ◽  
Conditional Knockout ◽  
High Pulse Frequency ◽  
High Pulse ◽  
Males And Females ◽  
G Protein Coupled ◽  
In Vitro Data

Abstract GnRH regulates gonadal function via its stimulatory effects on gonadotropin production by pituitary gonadotrope cells. GnRH is released from the hypothalamus in pulses and GnRH pulse frequency differentially regulates FSH and LH synthesis and secretion. The GnRH receptor (GnRHR) is a G protein-coupled receptor that canonically activates Gαq/11-dependent signaling upon ligand binding. However, the receptor can also couple to Gαs and in vitro data suggest that toggling between different G proteins may contribute to GnRH pulse frequency decoding. For example, as we show here, knockdown of Gαs impairs GnRH-stimulated FSH synthesis at low, but not high pulse frequency in a model gonadotrope-derived cell line. We next used a Cre-lox conditional knockout approach to interrogate the relative roles of Gαq/11 and Gαs proteins in gonadotrope function in mice. Gonadotrope-specific Gαq/11 knockouts exhibit hypogonadotropic hypogonadism and infertility, akin to the phenotypes seen in GnRH- or GnRHR-deficient mice. In contrast, under standard conditions, gonadotrope-specific Gαs knockouts produce gonadotropins at normal levels and are fertile. However, the LH surge amplitude is blunted in Gαs knockout females and post-gonadectomy increases in FSH and LH are reduced in both males and females. These data suggest that GnRH may signal principally via Gαq/11 to stimulate gonadotropin production, but that Gαs plays important roles in gonadotrope function in vivo when GnRH secretion is enhanced.

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