Hello All,
I have a question, what is a material of a (final) aperture were using in UV laser?
Mentioning related articles also will be great.
Best,
Mainly high power and solid state lasers we use ceramic material to generate a laser beam
For gas UV lasers such as eximer lasers of laser based on molecular nytrogen N2 the material of active media is gas ArF,XeCl of N2. The laser beams are Gauss shape distributed in space. As a rule for pulse laser on gas media the cavit contains one mirror from one side and window from anothe side. Because the apperture can be determined by width of Gauss beam of laser radiation. In case of solid state lasers such as YAG: Nd3+ laser it is often used the KDP and ADP crystals for harmonic of radiation generation such as 1064 nm, 532 nm, 355 nm, 265 nm. And we assume that the laser beam is also Gauss-shaped, too.
UV-grade fuzed silica is a common material for UV laser aperture as well as for lenses shaping the beam. Search for UV-grade silica and many manufacturers like Edmund Optics or Thorlabs provide technical specs with spectral transmission charts. If you need a material for extreme UV shorter then 200um (vacuum UV) then you need something special. If you need a limiting aperture, a metal or coated ceramic with good reflection in the UV should be used, and it is important to shape the aperture properly to guide the cut off part of the beam and to ensure good heat sink in order to make it durable.
Importance of Aperture in Laser Function Diaphragms are used for control laser beam intensity. An adjustable aperture is needed to either determine by trial and error the most appropriate opening size, or perhaps accommodate the need for differing focal points and diffusion rates. Use of iris diaphragms allow for such adjustments and even come with a choice of aperture material to manage of laser intensity. Baltic company EKSMA manufactores them several decades. Often, in laser beam optics the apperture is named the smallests size of Gauss beam of laser radiation and such value doesn't depends on any material. Now it is popular for UV laser lithography technique preparation, may be for radiation with wavelength 20 nm or even less. Usually, for UV radiation the quartz optics is used.
By this way, the diapragms can be performed of different materials such as metal but the main role of diapragm is cutting of tails of Gauss space distributed laser beam in plate perpendicular to the direction of laser beam propagation. You can surely manage the intensity of radiation by increasing or decreasing the radius of such diaphragm that would be control of parts of laser beam penetrating through the cavity of laser and out of it. The material of apperture is slightly strange because the apperture is technical parameter of laser beam with Gauss shape, only mathematical value of size of Gauss shaped radiation. Its material may be surely only the transparent for laser radiation and nothing more.
EKSMA reference is following: "Like all components of laser systems, optical aperture plays a big role in the function of the light beam used. By altering the size of the opening, a beam’s focus range, size, diffraction rate, and more are impacted. The customizable nature of a laser, particularly when an adjustable iris diaphragm is added, has allowed these tools to be useful across many disciplines and continues to encourage new and innovative applications."
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