1|8J.V. van Heijningen Cables finished! Assemble/ Disassemble Type B Payload LED selection measurements NAOJ GW Meeting, May 8 th, 2014

2|8J.V. van Heijningen Cables finished! Assemble/ Disassemble Type B Payload LED selection measurements 10 cables from bottom filters to OSEMs

3|8J.V. van Heijningen Cables finished! Assemble/ Disassemble Type B Payload LED selection measurements Wire lengths and masses are wrong!

4|8J.V. van Heijningen Cables finished! Assemble/ Disassemble Type B Payload LED selection measurements Measurement set-up intensity noise Determined with the first (!) fully assembled OSEM what current to run the LED, now with collimator, to have -12V on U TIA output: R s,LED = 300  U LED = 8V I LED ≈ 25mA For fast comparative measurement, LED is run in a simple set-up at 25 mA and ASD on the U TIA signal is taken First, a dependence of intensity noise on the LED intensity magnitude is investigated

5|8J.V. van Heijningen Cables finished! Assemble/ Disassemble Type B Payload LED selection measurements Intensity noise first batch of LEDs RMS determined by f df from 1-40 Hz

6|8J.V. van Heijningen Cables finished! Assemble/ Disassemble Type B Payload LED selection measurements Measurement set-up angular distribution OSEM optics LED Lens (f = 8mm) CCD Camera 1 DoF TrSt with end-stop

7|8J.V. van Heijningen Cables finished! Assemble/ Disassemble Type B Payload LED selection measurements Determining the optimal lens position Image analysis code: Determine maximum and a radius in which every value is 95% or higher of this value Middle of this circle is the defined as the middle of the blob Square with edges equal to the radius (half the diameter) to determine the fall of intensity with respect to the ‘0mm’ image When lens is at optimal position, radius shouldn’t change and power shouldn’t fall (as)much

8|8J.V. van Heijningen Assemble/ Disassemble Type B Payload LED selection measurementsNext weeks’ plan In my last weeks here, I’d like to… I’ll be at NAOJ until May 23, so 2 weeks to go… Select the 10 LEDs that will provide low(est) noise, most linear read-out for the OSEMs in their ‘new’ set-up (with collimator lens) Calibrate 10 OSEMs using the calibration stage (last part received last week!) Attach OSEMs to full type B payload prototype in their individual regions of highest sensitivity and linearity Use these 10 OSEMs in a feedback loop to damp the resonant modes of the Test Mass stage (3 DoFs) and Intermediate Mass stage (6 DoFs)