40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  TCS elog  Not logged in ELOG logo
Entry  Fri Jul 23 10:33:08 2010, Aidan, Computing, Hartmann sensor, Dalsa camera ADC 8th digitizer error  histogram_of_dalsa_intensity.pdf
    Reply  Fri Jul 23 19:52:49 2010, Aidan, Computing, Hartmann sensor, Dalsa camera ADC 8th digitizer error  image-location-of-excess_pixel_count_pixels.jpg
Message ID: 73     Entry time: Fri Jul 23 19:52:49 2010     In reply to: 70
Author: Aidan 
Type: Computing 
Category: Hartmann sensor 
Subject: Dalsa camera ADC 8th digitizer error  

I've attached an image that shows the locations of those pixels that record a number of counts = (2*n-1)*128. 

The image is the sum of 200 binary images where pixels are given values of 1 if their number of counts = (2*n-1)*128 and 0 otherwise.

The excess of counts is clearly coming from the left hand tap. This is good news because the two taps have independent ADCs and it suggests that it is only a malfunctioning ADC on the LHS that is giving us this problem.

Quote:

I plotted a histogram of the total intensity of the Hartmann sensor when illuminated and found that the 128 count problem extends all the way up through the distribution. This isn't unreasonable since that digitizer is going to be called on mutliple times.

First things first, the value of 128 equals a 1 in the 8th digitizer, so for a 16-bit number in binary, it looks like this: 0000 0000 1000 0000 and in hex-code 080

The values of the peaks in the attached distribution are as follows:

 

Number of counts Hex Code

128

 080
384  180
640  280
896  380
1152  480
1408  580
1664  680
1920  780
2176  880
2432  980
2688  A80
2944  B80
3200  C80

 

 

Attachment 1: image-location-of-excess_pixel_count_pixels.jpg  62 kB  | Hide | Hide all
image-location-of-excess_pixel_count_pixels.jpg
ELOG V3.1.3-