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Message ID: 1189     Entry time: Thu Dec 2 17:11:36 2010
Author: Frank 
Type: Computing 
Category: Pulser 
Subject: hardware & software updates 

made the following changes to optimize the quantity and quality of data taken:

  • reduced camera image size to region of interest by using a special camera function where you only read a defined area of the camera chip. Image size is now 640x480 showing only the photodiode.
  • added white LED to get some slight illumination in order to see where the chip actually is on the picture. White LED can be turned on/off via individual hardware channel (dev1/port1/line3)
  • had some timing issues showing part of the pulse in some of the pictures. changed code to avoid that.
  • added cylindrical lens to compensate for angle of red laser beam hitting the target
  • added control for pixel clock, exposure time, hardware gain, area of interest etc.
  • changed JPEG compression level to minimum compression (value 1000)
  • reduced resolution for dark noise spectrum to reduce measurement time. Now total cycle time is about 15min for 200 pulses and all data taken. Pictures are taken after every single pulse.
  • increased step size for i/v-curve to 20mV. Taking now 1005 points from 100mV (forward bias) to -20V (reverse bias).
  • Taking independent measurements at -10mV and 10mV to calculate shunt impedance.


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