OSEMs are preliminarily tested with a new OSEM test bench in a non-clean environment. The OSEM's LED and PD are operated by a test circuit (not an actual satellite box, but I and Okutomi-kun have just copied requred parts...)
The conbinations under test are:
- New LED holder with TSTS7100 and new PD holder
- Old LED holder with OP232 and new PD holder (NOTE!)
- Old LED holder with OP232 and old PD holder (NOTE)
NOTE: the "old" LED holder cannot hold a lens with the same manner as the ones used in TAMA300 SAS prototype now, as it is revealed that the adhesive of lens to the "lens holder" inside the LED holder cannot be usable in vacuum. I just make the lens holded somehow....... so the distance from the LED and the lens are changed. However, from the rough measurement of beam profile of light of the ones, I got impression that such a change of positions doesn't have effects on the performance... (preliminary)
What to be confirmed is the linear range. I'd like to compare the range with the one used in TAMA300 SAS prototype.
So far the linear range are almost all the same.
Obviously when the linear range is such, we don't need to use such a large area photodiode; it is too large and hard to fit new and old designed PD holder. A small aperture PD would have smaller capacitance, and that makes the cricuit easliy stabilized.
... and 4. Plot of data by Sekiguchi-kun for TAMA-OSEMs; the data's range differs from our setup so I just lineary scaled the vertical axis. It appears that the linear range would not change.
