Ocean Optics NanoCalc - Manual (Page 24)

Ocean Optics Germany GmbH Thin Film Metrology
23
7.2 Main menu “Screen”
7.2.1 Spectrometer data
The 4 spectrometer coefficients are displayed for
information purposes. They are automatically set by
the Thinfilm.ini file which is specific for each single
system.
Changing these values will screw up the system and
is therefore password protected and only accessible
for technical service.
For calibration purposes you may change these
values (with a password and only within several
percent deviation from your original values).
physical meaning:
These 4 numbers are the coefficients in a formula that shows the dependence between wavelength (in
nanometers) and pixel number of your spectrometer according to the following formula:
3
3
2
2 1
P C P C P C I ⋅ + ⋅ + ⋅ + = λ
with:
I
= intercept
C
1
= first coefficient
C
2
= second coefficient
C
3
= third coefficient
P = pixel number
Hint: Ask your hardware supplier if you have the impression that it might be necessary to recalibrate the
spectrometer (a red HeNe-laser should show 632.8 nm)
7.2.1.1 Integration time
Whenever you change this value, it is written to disk (in file “Thinfilm.ini”) and will be used as a startup value.
How to change integration time:
1. method:
To check integration time rapidly, use continuous mode button. You may change the value of integration time
by +1 msec or +10 msec or -1 msec or -10 msec within a mouse click. Try to achieve a maximum signal of
20 - 90 % of total range. This value will depend very much on the reflectivities of your reference materials,
your substrate material and your layer material.