Variable Attenuators for High Power Lasers
Diffractive attenuators control the power of laser radiation using diffraction
gratings. Since phase diffraction gratings do not absorb light they can be used for
high-power laser radiation (cw, pulsed). Variation of grating parameters along the
substrate results in variable transmission at a given wavelength.
Diffractive attenuators can be designed for wavelength from deep UV till IR for laser
powers up to 250W/cm2 in CW and 1000mJ/cm2 in 10ns pulses.
Principle of operation
Light beam passing through a diffractive grating is partially deflected into several diffractive orders, which get subsequently blocked by diaphragm. Thus the zero order beam (does not change the direction of propagation) is attenuated. The intensity of output radiation Ioutput depends on the grating design and wavelength of input beam. By changing the grating parameters one can control the power of output radiation1. The transmission coefficient of such an attenuator is h = Ioutput/Iinput..
Key features
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High power attenuator: Diffractive attenuators can control high power laser radiation, either pulsed or continuous (cw) laser beams due to non-absorbing phase gratings. |
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Flexible design of transmission function: The dependence h(j) of the attenuator transmission on rotation angle j can be designed by computer according to the customer's requirements. |
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Low cost mass-fabrication: Laser lithographic methods allow one to produce attenuators by binary optics technology with significant price decrease for larger quantities. |
Applications
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Beam-modulators for high power lasers (Nd:YAG-, Argon-, Excimer-...) for material processing (e.g. marking, ), scanner systems, etc. |
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Beam-splitters with adjustable splitting coefficient and attenuation. |
Attenuator design
Specifications
| Substrate material - surface flatness - wedge - outside-, inside diameter - thickness - clear aperture Design wavelength Transmission range Transmission function Deviation from linearity of transmission Polarization Coating S1, S2 Damage threshold Cleaning |
UV grade fused silica l/4 @ 532nm over clear aperture <20 arcsec 60 mm, 8mm 4 mm 10 mm 532nm, 1064nm (others wavelengths on request) T = 0.01 (0.025) – 0.95 ± 5% over 340o linear (approximated by stair case with 20 steps) <5% Transmission not dependent on polarization Broadband antireflection coating, R532/1064<0.3% 250 W/cm2 -CW, 1000 mJ/cm2 with 10ns pulses Non-abrasive method, acetone or isopropyl alcohol |
Diffractive attenuator with mount
Related Products:
Near-IR Viewers
Narrow-Band Holographic Filters (Notch Filters)
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