Gaussian Fit

The new camview has features of Gaussian and super-Gaussian fit, showing FWHM and 1/e2 width.

In "Show/hide", select "projection" then box 1, box 2, vertical, and horizonal lineout will appear. 

  • box 1:
    • The users choose the crosshairs' position (2 in this case) to show lineouts
    • ROI Avg: this will show integral average over both directions
    • Auto range: this will automatically adjust the intensity range
    • Gaussian: Gaussian fit, I = I0*exp{-2(x/w)^p}, in which p =2, FWHM = 1.177w and 1/e2 width = 2w.
    • Super Gaussian ( p=4): This is 4 order super Gaussian fit. p=4, FWHM= 1.5345w; 1/e2 width = 2w. 
    • Super Gaussian (p=6): This is 6 order super Gaussian fit. p=6, FWHM = 1.6762w. 1/e2 width = 2w. 
  • box 2:
    • Spatial calibration is a user-set value, otherwise, it will be 1 as default. The unit is mm/pixel.
    • The FWHM and 1/e2 width (and sigma) will be multiplied by the spatial calibration value. FWHM (mm) = FWHM (pixel) * spatial cal(mm/pixel).
    • For Gaussian, FWHM = sigma * 2sqrt(2ln2) = sigma*2.355. And, 1/e2 width = 1.699 FWHM.
    • The super Gaussian is commonly useful for the laser beam with a "flat top" profile. When p=4, FWHM= 1.5345w and 1/e2 width = 2w. When p=6, FWHM = 1.6762w. 1/e2 width = 2w. 

 

Camera Trigger

  • box 3
    • Camera Mode: choose trigger or free run. "Sync In 1" is the trigger. 
    • switch between 10Hz and single shot: in MEC Home> EVR > New MEC LAS EVR > Front Panel B change to 182 (single shot) from 43 (10Hz)
    • Gain: gain is an electronic amplification of the video signal. It adds more voltage to the pixels on your imager (CCD or CMOS) causing them to amplify their intensity and therefore brighten your image.  This voltage increase is measured in decibels (dB) and is calculated using this equation: Gain (in dB) = 20 x log(Voltage Out / Voltage In). We usually choose 0 for linear intensity. For small signal you can use higher number. 
    • Aquisition time: 0.001 sec is good. You might not catch the laser pulse when set <0.001sec.
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