Differences

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--- stm:march_16_revolution [2016/03/04 08:57] – galli
+++ stm:march_16_revolution [2016/03/04 09:31] (current) – galli
@@ Line 4: / Line 4: @@
 Issues in this category are such that they affect the essential functionality of the instrument.
-  * AFM is not working. RHK staff has maintained there is some issue with the optics, first the laser amplifier was not working and then it was the photodiode. The photodiode was troubleshoot in the end of February 2012 and was indeed disconnected in at least one quadrant. Bert has been notified about this and it should be rectified during the March revolution.
+  * AFM is not working. RHK staff has maintained there is some issue with the optics, first the laser amplifier was not working and then it was the photodiode. The photodiode was troubleshoot in the end of February 2016 and was indeed disconnected in at least one quadrant. Bert has been notified about this and it should be rectified during the March revolution.
     * Update [20160304]: There has been significant progress on this issue. The photo diode is fixed on both sides. On one side the cable had simply come off and on the other side the soldering from this autumn short-circuited the cable as it connected the shield with the core. The connector was changed to a new one and it was soldered on by ELD with UHV compatible solder (it is supposed to be crimped but the cable was too thin). The laser has also been tested and works fine. An attempt to test this with the system has been made with the laser aligned on the cantilever but the signal remained low. The signal directly from the photo diode however, is still in the range of 200-300 mV when the laser is on. When the preamplifier from RHK is connected it goes down to single millivolt range. RHK has been notified of this on 20160304. One last thing that can be tested is to tune a cantilever with the low signal to indicate if the piezo on the stage works properly. Additionally, the laser spot on the photo diode is very large, almost covering all quadrants. If it is a differential amplifier, this would give a low signal if the signal in all the quadrants are almost the same. Figuring out if this is normal behavior would be good.
   * LEED is not working. The manuals procedure for starting the LEED was followed and the current readout did not show any current. The filament was removed and seems OK, so other troubleshooting ideas have to be explored. VACGEN has been contacted for suggestions. The power supply will be given to the ELD in the first week of March 16.