Scanner (galvanometer) position detector

[SpaceQuester]

I have find CamTech 6215 scanner datasheet, here is it: https://physics.ucsd.edu/neurophysics/Manuals/Cambridge/Cambridge%20Technology%20Model%206200%20Opti...
http://www.edmundoptics.com/lasers/laser-mechanics/dual-axis-galvanometer-optical-scanners/86809/
If I get voltage +/-3V on "+motor" and "-motor", I able to see the movement of mirror. It is good.
But what these abbreveatures are meaning: https://monosnap.com/file/S9sA9YMyPjp5q2NK2Yglc7kOKeIp6m ?
How can I detect current position of mirror?

[Buechsenschuetz]

I do not know this sensor in detail. The pin description uses some terms commonly used in electronics but I do not know about their special meaning or functionality in this case.

AGC = automatic gain control, so "AGC input" would be an input to the AGC and "AGC return" some current return path of the AGC

Diode common = common terminal of diodes

Shield = cable shield

Anyhow, as this is quite a costly product, the manufacturer should provide some technical documents and/or customer support. You should contact them for any detailed information. What you find with your link is rather some sales information and basic specs, but not a datasheet or manual a technician could use. As far as I dealt with Edmund Optics in Germany (not too much), they were competent people and able to support you for your application. 

[Henrik_Volkers]

Newer seen this device, but if you only have the raw galvanometer, the output for a position feedback seems to need a supply (AGC?) and the Ia / Ib is an position proportional current to diode common. Seems that there is a dual position diode build in and the AGC is the LED ... 

I would try to contact Edmund or Cambridge  and ask 🙂