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TOPAG Lasertechnik GmbH
Nieder-Ramstädter Str. 247
64285 Darmstadt
Telefon: +49 6151 4259 78
Telefax: +49 6151 4259 88 
E- mail: info [at] 

Diff. Variable Attenuator

DVA - Diffractive Variable Beam Attenuator


Diffractive attenuators control the power of laser radiation using diffraction gratings. Since phase diffraction gratings do not absorb light they can be used to attenuate also high-power laser radiation (cw, pulsed). Variation of grating parameters along the attenuator results in variable transmission at a given wavelength. Diffractive attenuators can be designed for deep UV till IR.


Bezeichnungen der Tabs

  • Description
  • Specifications
  • Pictures/Scheme
Tab 1

Principle of operation

Light beam passing through a diffractive grating is partially deflected into several diffractive orders which are blocked by diaphragm. Subsequently zero order beam along optical axis is attenuated. The diffraction efficiency and thus the intensity of output radiation Iout depends on the grating parameters. With variation of the grating parameters along the attenuator the transmission changes from Tmax to Tmin by 340° rotation of attenuator wheel (with T= Iout/Iin). Although diffractive attenuators are optimized for its design wavelength λ0, they will operate over a larger spectral range (λ0 ±15%) with minor attenuation range decreasing. The functional dependence of transmission function -e.g. its linearity- remains the same. Notice that the attenuator works also at λ0/3 of design wavelength, but has nearly zero effect at λ0/2.

Design and Operation

Attenuator includes grating wheel mounted in a special encapsulated housing with entrance and exit tubes. Housing and tubes are intended for blocking parasitic diffractive orders and absorbing of laser radiation. Tubes are suitable for less than 20Watt average power dissipation. Special finned radiators are required for higher laser power.

Order information

Each attenuator set includes attenuator disc within encapsulated housing, 2 radiator tubes (for blocking of diffracted light at entrance-/exit beam ports)

Design wavelength λ0(also suitable for λ0/3) Cat.-No.
1064nm ( 355nm) DVA1064
800nm (266nm, 248nm) DVA0800
532nm DVA0532
355nm DVA0355
others wavelength on request 



Tab 2

Substrate material UV grade fused silica (UVFS)
Surface flatness, wedge λ/4 @ 532nm over clear aperture, ≤ 30arcsec
Diameter-/thickness quartz substr. 60mm, 3mm
Width grating area /clear aperture 15mm/14mm (12mm with tubes)
Front side 2-dimensional binary phase grating
Back side AR-coating, R(l0) < 0.3% (effective for design wavelength)
Transmission range Tlinear ≥ 2% – 96% over 340°(deviation from linearity ≤ 5%)
Damage threshold ≥ 500W/cm²-cw
≥ 3J/cm²with 10ns pulses
≥ 1J/cm²with 150fs pulses (800nm, 1kHz)

Tab 3

Tab 3 Inhalt

Tab 4

Tab 4 Inhalt

Tab 5
Bild 1
 DVA 2b
Beschreibung 1
 DVA and tubes in case
Bild 2
 DVA 4
Beschreibung 2
 DVA with mounted tubes
Bild 3
 DVA Gehaeuse Achse eng
Beschreibung 3
 Dimensions of DVA
Bild 4
 DVA Schema klein
Beschreibung 4
 Principle operation scheme
Bild 5
 DVA Transmission
Beschreibung 5
 Typ. transmission of DVA
Bild 6
Beschreibung 6
Bild 7
Beschreibung 7
Bild 8
Beschreibung 8
Bild 9
Beschreibung 9
Bild 10
Beschreibung 10
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