scholarly journals YAG Laser Rod 3D Corrective Process Optimization through Tool Influent Function Shape Inspection

2020 ◽  
Vol 10 (22) ◽  
pp. 8194
Author(s):  
Frantisek Prochaska ◽  
Karel Nejezchleb ◽  
Jiri Benes ◽  
Ondrej Matousek ◽  
David Tomka
Keyword(s):  
Influence Function ◽  
Yttrium Aluminum Garnet ◽  
Solid State Laser ◽  
Polished Surface ◽  
Elastic Membrane ◽  
Tool Influence Function ◽  
Yttrium Aluminum ◽  
Optical Production ◽  
Shape Inspection

Due to the increasing demands on the quality of solid-state laser active media production based on yttrium aluminum garnet Y3Al5O12 in the form of rods with precisely machined faces, the possibilities of applying subaperture 3D corrective polishing in this segment of optical production were studied. For the considered laser rod diameters of up to 10 mm, the corrective process had to be optimized to achieve a stable, suitably shaped tool influence function at the full width at half maximum of approximately 1.5 mm, enabling 3D shape corrections with sufficient lateral resolution. For this purpose, a number of experiments were performed using both tools based on a flexible elastic membrane inflated by compressed air and tools with a viscoelastic head, and the effect of the tool-polished surface interaction was studied and analyzed.

Yag Single Crystals for Scintillators of Stem

1990 ◽  
Vol 48 (1) ◽  
pp. 166-167
Author(s):  
M. Hibino ◽  
K. Irie ◽  
R. Autrata ◽  
P. schauer
Keyword(s):  
Single Crystals ◽  
Yttrium Aluminum Garnet ◽  
Light Guide ◽  
Detection System ◽  
Polished Surface ◽  
Detective Quantum Efficiency ◽  
Backscattered Electrons ◽  
Electron Detection ◽  
Yttrium Aluminum ◽  
Phosphor Screens

Although powdered phosphor screens are usually used for scintillators of STEM, it has been found that the phosphor screen of appropriate thickness should be used depending on the accelerating voltage, in order to keep high detective quantum efficiency. 1 It has been also found that the variation in sensitivity, due to granularity of phosphor screens, makes the measurement of fine electron probe difficult and that the sensitivity reduces with electron irradiation specially at high voltages.In order to find out a preferable scintillator for STEM, single crystals of YAG (yttrium aluminum garnet), which are used for detecting secondary and backscattered electrons in SEM were investigated and compared with powdered phosphor screens, at the accelerating voltages of 100kV and 1 MV. A conventional electron detection system, consisting of scintillator, light guide and PMT (Hamamatsu Photonics R268) was used for measurements. Scintillators used are YAG single crystals of 1.0 to 3.2mm thicknesses (with surfaces matted for good interface to the light guide) and of 0.8mm thickness (with polished surface), and powdered P-46 phosphor screens of 0.07mm and 1.0mm thicknesses for 100kV and 1MV, respectively. Surfaces on electron-incidence side of all scintillators are coated with reflecting layers.

First-Surface Scintillator for Low Accelerating Voltage Scanning Electron Microscopy (SEM) Imaging

2018 ◽  
Vol 24 (5) ◽  
pp. 488-496
Author(s):  
Marian B. Tzolov ◽  
Nicholas C. Barbi ◽  
Christopher T. Bowser ◽  
Owen Healy
Keyword(s):  
Indium Tin Oxide ◽  
Yttrium Aluminum Garnet ◽  
Detection System ◽  
Conducting Layer ◽  
Backscattered Electrons ◽  
Electron Detection ◽  
Yttrium Aluminum ◽  
Low Energy Electrons ◽  
Spectrally Resolved

AbstractHighly luminescent thin films of zinc tungstate (ZT) have been deposited on top of conventional scintillators (Yttrium Aluminum Perovskite, Yttrium Aluminum Garnet) for electron detection in order to replace the need for a top conducting layer, such as indium tin oxide (ITO) or aluminum, which is non-scintillating and electron absorbing. Such conventional conducting layers serve the single purpose of eliminating electrical charge build-up on the scintillator. The ZT film also eliminates charging, which has been verified by measuring the Duane–Hunt limit and electron emission versus accelerating voltage. The luminescent nature of the ZT film ensures effective detection of low energy electrons from the very top surface of the structure ZT/scintillator, which we call “first-surfacescintillator”. The cathodoluminescence has been measured directly with a photodetector and spectrally resolved at different accelerating voltages. All results demonstrate the extended range of operation of the first-surface scintillator, while the conventional scintillators with a top ITO layer decline below 5 kV and have practically no output below 2 kV. Scintillators of different types were integrated in a detection system for backscattered electrons (BSE). The quality of the image at high accelerating voltages is comparable with the conventional scintillator and commercial BSE detector, while the image quality at 1 kV from the first-surface scintillator is superior.

The Pattern Scanning Laser (PASCAL®) Photocoagulator for Diabetic Retinopathy

2011 ◽  
Vol 04 (01) ◽  
pp. 94
Author(s):  
Szilárd Kiss ◽  
Joan W Miller ◽  
◽  
Keyword(s):  
Diabetic Retinopathy ◽  
Gold Standard ◽  
Laser Photocoagulation ◽  
Yttrium Aluminum Garnet ◽  
Solid State Laser ◽  
Scanning Laser ◽  
Fda Approval ◽  
Delivery Technique ◽  
Yttrium Aluminum ◽  
Operator Fatigue

For 40 years, laser photocoagulation has been the gold standard for the treatment of diabetic retinopathy (DR). Since receiving Food and Drug Administration (FDA) approval in 2005, the pattern scanning laser (PASCAL®) photocoagulator is emerging as a superior method of such treatment. PASCAL is a 532nm frequency-doubled neodymium-doped yttrium aluminum garnet (Nd:YAG) solid state laser that can be used for pan-retinal, focal, and macular grid photocoagulation in the setting of proliferative and non-proliferative DR. A more precise and predictable pre-determined pattern array may be delivered with more controlled spot spacing and predictable burn characteristics resulting in enhanced uniformity of laser treatment. Multiple spot delivery technique allows physicians to treat in a much shorter time, with less discomfort to the patient and diminished operator fatigue.

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