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Filter control

General infos

The filter control panel can be used to move in filters AND to calculate the transmission of the fundamental wavelength of the FEL and its 3rd harmonic.

The moving procedure is supervised by a protection system. First of all the fast shutter is closed before moving the filter wheel (to protect the filters during moving) and blocked till the movement is over. Then the fast shutter has to be opened again with the Fast shutter control button. It does not open automatically! 

In addition the pulse energy and the number of bunches in the FEL is monitored. IF the radiation dose exceeds a certain limit the filters can not be moved into the beam. Then the beam has to be attenuated using the gas attenuator to a range where the filters can be used again. More info: JdddFilterProtection

Current limits are:    :


Calculation of the transmission

The shown transmission values for the filters are based on the CXRO webpage AND on measurements performed at the PTB (data see below).

The measured transmissions may differ from calculated ones in certain wavelength ranges significantly. Since we do not have measured values for all filters / thicknesses there may be situations where the shown transmission may be e.g. smaller for a thinner filter of the same material (since it was measured) in comparison to a thicker (not measured) one ...


The transmission is given for the fundamental Wavelength and in addition for the third harmonic of the FEL ( which is typically 1% of the fundamental). The bars below the shown transmission are just a guide to the eye to distinguish between large and weak transmission easier. The values are calculated for the current wavelength set in the FEL. 


Since for certain combinations of filters the transmission of the third harmonic can be significantly higher than for the fundamental it may happen that more third harmonic as fundamental passes ... thus there is a warning indicating that this may be a problem ...

By pressing on the transmission values of a certain filter one can open the window showing the transmission as function of the photon energy / Wavelength:



To help finding the right filter setting one can also have an overview of all filters available and look on the transmission for a certain wavelength / photon energy independent of the actual FEL wavelength. Using the tab "transmission" one can type in a photon energy or wavelength → press "calculate transmission" and then see transmission of the fundamental and the 3rd harmonic for this wavelength ... (this is a separate transmission calculator and playing with it does not alter anything on the filter wheels or in the FEL / undulator settings!)


More (special) info

Mounted filters, replacement in N2 box

Filter transmission - expert info

  • The transmission data for the transmission calculation in jddd uses combined data from CXRO and the measures transmission from BESSY. This is also the reason that for some values there is a deviation from expected scaling (e.g. same material but different thickness) or tabulated values. The calculated data for extrapolating the experimental values  was scaled to fit the experimental values at the crossover.  
  • The transmission data can be found at e.g. (depending on the filter wheel) /export/doocs/server/blfilters2_server/data/ as files generated from CXRO. We use the WL range 0.5 nm to 60 nm 
  • Transmission of filters calculated from CXRO  as pdf for FLASH1 and FLASH2 filter wheels
  • AllFiltersPTB.pdf: Transmission of filters as measured by PTB as pdf (and here are the actual data of the measurements)
  • Transmission_PTB_CXRO.pdf : Transmission of Nb, Zr, Al, Si Luxel filters measured between 2.5nm and 25nm by the PTB in comparison with CXRO data
  • Experimental measurements for the transmission: Laurents transmissiont measurements for "Rohringer" Beamtime - shows deviations for Si !


Documentation of the filter protection in jddd


Data collection of FEL parameters and Filter damage


Filter materialThickness[nm]Wavelength [nm]pulse energy [µJ]# of BunchesApertures?Integral dose (mJ)Filter unitsurvived?dateComments











Al1001330013mm~3BL wheel 2hoursSept 2014Adrians beamtime
Al198131.84013mm~0.7BL wheel 2~10 minutesAugust 2014only in combination with Nb 385nm on wheel 1, Attenuator with Xe at 5% transmission (0.15mbar), Industry beamtime
Nb385131.84013mm~0.7BL wheel 1~10 minutesAugust 2014only in combination with Al 198nm on wheel 2, Attenuator with Xe at 5% transmission (0.15mbar), Industry beamtime
Nb197132.54013mm~1BL wheel 2~10 minutesAugust 2014only in combination with Al 423 nm on wheel 1, Attenuator with Xe at 5% transmission (0.15mbar), Industry beamtime
Al423132.54013mm~1BL wheel 2~15 minutesAugust 2014only in combination with Al 423nm on wheel 1, Attenuator with Xe at 5% transmission (0.15mbar), Industry beamtime
Al101132.54013mm~1BL wheel 2~15 minutesAugust 2014only in combination with Al 423nm on wheel 1, Attenuator with Xe at 5% transmission (0.15mbar), Industry beamtime
Al298132.54013mm~1BL wheel 2~15 minutesAugust 2014only in combination with Al 423nm on wheel 1, Attenuator with Xe at 5% transmission (0.15mbar), Industry beamtime
C Al C500132.54013mm~1BL wheel 2~15 minutesAugust 2014only in combination with Al 423nm on wheel 1, Attenuator with Xe at 5% transmission (0.15mbar), Industry beamtime
Al423132.54013mm~1BL wheel 1~1 hAugust 2014Industry beamtime, Attenuator with Xe at 5% transmission (0.15mbar)
Al423137013mm0.07BL wheel 1~1 hAugust 2014Industry beamtime
Al193135213mm0.05BL wheel 1~1 hAugust 2014Industry beamtime
Al1931350-8013mm, 5mm, 10mm~0.1BL wheel 1~30minAugust 2014Industry beamtime
Si4191915-20873mm1.3BL wheel 136hJune 2014
Al4001915-20873mm1.3BL wheel 1many hJune 2014
Zr200192-3771mm0.2BL wheel 1few hJune 2014
Al100136-8151mm !~ 0.1BLshort ? - then BROKENJan 2014
Al20041801none, but 2-3 mm beam in the hall~ 0.2BLyes, minutesDec 2013
Al40041801none, but 2-3 mm beam in the hall~ 0.2BLyes, minutesDec 2013
Si3N43504.31801none, but 2-3 mm beam in the hall~ 0.2BLyes, minutesDec 2013
Al1004.31801none, but 2-3 mm beam in the hall~ 0.2BLBROKENDec 2013
Si2204.31801none, but 2-3 mm beam in the hall~ 0.2BLBROKENDec 2013
Zr2204.31801none, but 2-3 mm beam in the hall~ 0.2BLBROKENDec 2013
Al1006.880303mm2.4BLBROKENMar 2011






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