Ocean Optics ElliCalc - Manual (Page 21)

Ocean Optics Germany GmbH Thin Film Metrology
20
You may check the value of integration time at any time without entering the menu OPTIONS: Put your
mouse cursor over the button MEASURE and wait for about 2 seconds: a small window will pop up to in-
form you about integration time, samples to average and boxcar width.
These values correspond to the channel A ("master spectrometer") if you use a double spectrometer.
7.2.1.2 Boxcar width
physical meaning:
The OceanOptics spectrometer is able to average over some pixels to increase signal/noise-ratio.
A boxcar width of 1 pixel means no averaging at all (which is an ideal situation and would correspond to a
very narrow fiber). This has to be used if you want to measure very thick layers (like 50 micrometers of re-
sist)
A boxcar width of 5 pixels means an averaging over 2 pixels on the left side and 2 pixels on the right side
(= 5 pixels altogether). This averaging routine is shifted from the left side of the simulated spectrum to the
right side with a step size of 1 pixel only. Values of 5-9 are recommended if you want to measure films in
the range of 1 micrometer or less as you get a better signal-to-noise ratio.
hint:
You may check boxcar width at any instance without entering the menu OPTIONS: Put your mouse cursor
over the button REFERENCE or MEASURE and wait for about 2 seconds: a small window will pop up to
inform you about integration time, samples to average and boxcar width.
These values correspond to the channel A spectrometer if you use a double spectrometer.
7.2.1.3 Samples to average
Whenever you change this value, it is written to disk (in file “Thinfilm.ini”) and will be used as a startup
value.
physical meaning:
The Ocean Optics /spectrometer is able to average over some runs to increase signal/noise-ratio.
Tips:
Try to use small values for Samples To Average while keeping the lamp intensity as high as possible (to
get short measuring times). This is especially important in mapping mode.
You may check Samples To Average at any instance without entering the menu OPTIONS: Put your
mouse cursor over the button MEASURE and wait for about 2 seconds: a small window will pop up to
inform you about integration time, samples to average and boxcar width.
7.2.1.4 Internal correct for dark
If you choose this option, dark current is corrected automatically (see button “measure”).
The Ocean Optics Spectrometer is able to measure the dynamic dark current internally within a couple of
pixels that are NOT irradiated by external light, and is correcting dynamically.
7.2.1.5 Dark button