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I measured the optical power at the output of the objective on my EXFO
fed TE2000E inverted scope. The absolute numbers are not that important,
but just for general info -- they were around 0.5-1.0mW though
a 40x/NA=0.95 air objective, for wavelengths of 405nm-575nm (405, 470,
546 and 575nm center wavelength of excitation filters)
My question to this list concerns the ratio of intensities in the 12,
25, 50, and 100 percent output positions of the EXFO source.
I found the following ratios:
power(100)/power(50) was 13-15. (Four measurements at 405nm, 470nm,
546nm, 575nm)
power(50)/power(25) was 4.1-4.6 (Four measurements, as above)
power(25)/power(12) was 2.1-2.4 (Four measurements, as above)
There was a slight but reproducible increase in output when the 25 was
approached from 12, versus switching 50-->25, and similarly for 25-->50
versus 100-->50.
I understand that the EXFO changes its light output by inserting an
aperture between the source and the input to the liquid light guide.
These apertures are on a wheel which rotates. The last observation may
indicate that the wheel sits slightly differently depending on the
direction of rotation. This different was relatively small (under 5%).
However, the massive difference in going from 100 to 50 surprised me. I
thought that these numbers were roughly the percentage of total output
power.
BTW, since my TE2000E has two ND filters (1/8 and 1/4) which are
positioned between the light guide input and the filter cubes, I used
then to confirm that my power meter and detector were behaving as
expected. That is, inserting the 1/8 or 1/4 ND filters (or both)
produced the expected result.
Is this the normal behavior, and is it seen by other EXFO users?
Have any EXFO users done this test?
There are a number of similar metal-halide light sources around. Do
other sources behave this way?
--aryeh
--
Aryeh Weiss
School of Engineering
Bar Ilan University
Ramat Gan 52900 Israel
Ph: 972-3-5317638
FAX: 972-3-7384051
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