Shutter Inspection and Testing for new Teflon coated blades

Objective: To create a shutter timing profile for new double sided Teflon coated shutters under conditions similar to those seen at MRC’s OTF. To compare the profile from the new shutters to the old, AlMgF2 coated shutters.

Set up: The final setup of the test used the following: –1050 peak LED from Epitex Inc. (L ) –Two (2) double sided Teflon coated Uni-Blitz shutters (VS25S2T1) –One (1) AlMgF2 coated Uni-Blitz shutter (VS25S2ZM0) –Uni-Blitz shutter driver (T132) –Stanford Delay Generator (DG 535) –Fast Focusing Lens –Electro-Optics Technology InGaAs p-i-n photodetector (ET-3040) –Data read by Tektronix TDS 3054 oscilloscope.

Individual Component Info: LED: –Incoherent source –Emits at 1050 nm peak (from ) –Powered by a standard C 1.5 V battery in line with a 28.7 ohm resistor Provided 1.64 V of power with 57 mA of current –Spec sheet lists radiated power at 2.5 mW typical under these conditions.

Individual Component Info: Double Sided Teflon (and AlMgF2 coated) Shutters: –Mounted on a three axis translation mount –Power signal came directly from Uni-Blitz T132 –Entire mount was removed for shutter exchange, was then replaced and realigned to lens

Individual Component Info: Manufacturer’s standard shutter profile for V25 series taken from Uni-Blitz’s online website

Individual Component Info: Shutter Driver (T132) –Triggered externally –Received a triggering pulse from the Stanford (DG535) connected to the Trig port on the back –Sent a triggering profile to the oscilloscope from the Pulse Out connection on back. –Set to have a shutter exposure time of 8 ms.

Individual Component Info: Stanford Delay Generator (DG 535) –Pulse A was set to fire on T –Pulse B was set to fire at A s (92 ms ) –Resulted in a 10 Hz frequency with an 8 ms exposure time –Output signal was in the form of A_ | --- | _B –Reverse signal was sent to oscilloscope

Individual Component Info: EOT Photodetector (ET-3040) –Standard InGaAs p-i-n detector –Active area of 1 mm –Has ~.65 A/W absolute responsivity at 1050 nm –Biased voltage of 6 V –Ran in linear mode –Output run directly to the oscilloscope

Individual Component Info: Tektronix Oscilloscope (TDS 3045) –Capable of 5 GS/s –Used three of four channels CH1: output from shutter trigger –50ohm impedance –Scale of 500mV CH2: output from delay generator (A --- |_| --- B) –50ohm impedance –Scale of 100mV CH3: output direct from detector –1 Mega ohm impedance –Scale of 5V All were DC coupled –Data could be analyzed directly on the scope or exported as comma separated value files to be plotted with a computer.

Initial Problems Hiccups in the shutters opening and closing could be heard at various times Most commonly seen at the beginning shortly after shutter initialized. Would usually subside and were rarely heard after a prolonged period. Using the scope it appeared to be caused by a mis-hap in the Stanford DG 535 No data collected during these events was used in profiling the shutter

Shutter Hiccup (output from shutter driver) Hiccup Normal Pulse

Hiccup Normal Pulse Blue- Shutter Driver Magenta- External Trigger Shutter Hiccup (Delay generator and shutter driver)

Initial Problems Finding a detector that would meet all needs was difficult First detector used: –Newport 818-IR photo detector Would not respond fast enough Best rated frequency was 10 Hz Had large rise time Did not recharge quickly

Newport 818-IR Detector

Initial Problems Second detector used: –Electro-Optics Technology ET-3020 InGaAs p-i-n detector Good responsivity Rated to a frequency of 2.5 MHz Had no bias across it –Would respond in photovoltaic mode with a sharp spike upon change in incident light. –Quick sharp pulse up and down both upon open and close of shutter

ET-3020 Detector

Data Collection Data collection began once a suitable detector was found –Used EOT’s ET-3040 –Data was collected using the self triggering mechanism on the scope –Taken in 40 ms segments (4 ms /division) –Scale was taken to smaller divisions for more precise measurements –Voltage readings from the sensor were reduced by a factor of 20

Results 344 us 11.6 ms 2.12 ms 7.12 ms 2.44 ms 1.40ms1.84ms 1.64 ms

Results 336us344us 1.88 ms 1.6 ms 7.16 ms 1.36 ms 2.2 ms 11.7 ms 2.44ms

Results 336us344us 3.44ms 4.32ms 7.44ms 1.74ms 2.68ms 2.48 ms 14.2ms

Comparing to Manufacturer’s Data The timing image from the manufacturer’s website was used as a base for comparison The comparison is presented on the following slide.

Time FrameSn Sn Sn Manufacturer O-A1.64 ms1.88 ms2.48 ms3 ms A-C2.44 ms 4.32 ms3 ms O-C4.08 ms4.32 ms6.8 ms6 ms C-E7.12 ms^7.16 ms^7.44 ms^2 ms* E-G2.12 ms2.2 ms2.68 ms5 ms A-G11.6 ms11.7 ms14.2 ms10 ms ^ denotes time spent at max exposer * denotes min dwell time with min input pulse Dashed line indicates time for a typical 8 ms exposure pulse G E^

Analysis It appears that the manufacturer’s data is a compilation of all types of shutters in the VS25 series. The Teflon coated shutters had slightly shorter time from start of open to full open the manufacturer’s specs while the AlMgF2 shutters had a slightly longer time. The delay from signal to start of open was shorter for all three shutters tested. The total close time for all shutters appears to be much faster than the manufacturer given data. –For Teflon coated blades is was less than half The total window time for the Teflon blades was around 12 ms while for the AlMgF2 it was 14 ms.