The last item currently we are missing for HAM6 is a QPD sled (see 8633) from the ISC point of view. But the preparation of the sled is not going well.

ModeMaster is not functioning:

Yesterday, I was going to start preparing the sled which requires the use of a ModeMaster for the precision lens adjustment. However it seems that the germanium detector of our ModeMaster is not functioning for some reason. It worked fine with a different silicon detector, but didn't work with the germanium one. I looked at the output from the detectors with an oscilloscope. The silicone showed a square-looking, 20 Hz-modulated output and the amplitude seems depending on the amount of laser power, which makes sense to me. However, once I switched the detector to the germanium one, it showed a similar square-looking wave, but the amplitude didn't depend on the laser power. Moreover, the signal seems just railing -- it swung from -5 to 13 V in every square wave. I incline to conclude that the germanium detector became broken.

Trying to get a replacement:

I already sent an email to Adam and Valera in Livingston to see if they can lend us their ModeMaster. At the same time, I will get some technical support from the company and hopefully get some replacements.