Monthly Update

1|8J.V. van Heijningen ([email protected])

Cables finished! Assemble/ Disassemble Type B Payload LED selection measurements

Monthly UpdateNAOJ GW Meeting, May 8th, 2014



10 cables from bottom filters to OSEMs



Wire lengths and masses are wrong!



Measurement set-up intensity noise

Determined with the first (!) fully assembledOSEM what current to run the LED, now with collimator, to have -12V on UTIA output:

Rs,LED = 300W ULED = 8VILED ≈ 25mA

For fast comparative measurement, LED is runin a simple set-up at 25 mA and ASD on theUTIA signal is taken

First, a dependence of intensity noise on theLED intensity magnitude is investigated



Intensity noise first batch of LEDs

RMS determinedby f df from 1-40 Hz



Measurement set-up angular distribution

OSEM optics

LED

Lens (f = 8mm)

CCD Camera

1 DoF TrSt

with end-st

op



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


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 theTest Mass stage (3 DoFs) and Intermediate Mass stage (6 DoFs)

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Monthly Update