8:13 AM 8/24/2018 A sawtooth pattern has developed in the spectrum. I'm not sure if it's due to the CCD binning not being aligned with the slit. With longer exposure times, there's a more urgent need to close the CCD shutter during readouts and work harder to block off stray light sources.
white light tests
50x lens
50x lens with reversed frame pixel order
Post head, pre raman:
Direct input to spectrograph
10x lens
Post head pre raman:
Direct into spectrograph:
after fiddling:
after adjusting spectrograph:
background in each frame looks the same:
same image after S-G processing
closeup stitching looks but
background looks identical, as if
the whole sensor is acting like one pixel.
Suggests electrical failure at the CCD
since the background noise is higher than
before.
Checking for wiring problems... Not finding wiring problems.
Shading the CCD seems to show all pixels responding.
I don't know why the spectrum is identical between frames...
Notch test. Notch is to the right of the laser line.
Cut on at 150 kaysers
Source: LED flashlight before Raman filt.
Alternating red and blue indicate separate CCD frames.
But still shows scalloping/sawtooth pattern.
Source: flashlight after Raman filt.
The Hamamatsu S7031 is an FFT type (Full-Frame Transfer) CCD which
does not have an internal storage register. This requires use of
and external shutter mechanism during readouts?
Conclusion: scalloping/sawtooth pattern is most likely
caused by a yaw and/or roll existing between
the slit and the linear CCD. A yaw would probably be
a less noticeable than a roll.
50x lens with reversed frame pixel order
Post head, pre raman:
Direct input to spectrograph
10x lens
Post head pre raman:
Direct into spectrograph:
after fiddling:
after adjusting spectrograph:
background in each frame looks the same:
same image after S-G processing
closeup stitching looks but
background looks identical, as if
the whole sensor is acting like one pixel.
Suggests electrical failure at the CCD
since the background noise is higher than
before.
Checking for wiring problems... Not finding wiring problems.
Shading the CCD seems to show all pixels responding.
I don't know why the spectrum is identical between frames...
Notch test. Notch is to the right of the laser line.
Cut on at 150 kaysers
Source: LED flashlight before Raman filt.
Alternating red and blue indicate separate CCD frames.
But still shows scalloping/sawtooth pattern.
Source: flashlight after Raman filt.
The Hamamatsu S7031 is an FFT type (Full-Frame Transfer) CCD which
does not have an internal storage register. This requires use of
and external shutter mechanism during readouts?
Conclusion: scalloping/sawtooth pattern is most likely
caused by a yaw and/or roll existing between
the slit and the linear CCD. A yaw would probably be
a less noticeable than a roll.