Electronics overview

This document describes the control system of the STXM V microscope, and also of CryoSTXM II. We will build a total of three systems: one for STXM inboard, one for STXM outboard, and one for Cryo.

While it might be nice to equip cryo with a laser interferometer system in the fullness of time, for the moment we do not have the money (or a clear idea for a workable scheme) for a third laser interferometer. In the cryo system, we will use piezos with closed loop positioning provided in analog fashion by the PI electronics based on the capacitance micrometers as is done in the room temperature STXMs now. We will still use a Delta Tau board to provide the analog position info to the cryo piezos, but it will operate in open loop fashion with no interferometer feedback. (We could use a simple analog output board, but the Delta Tau board preserves symmetry among the three systems and gives us the path to equip cryo with a laser interferometer in the future).

We begin by summarizing the devices that each microscope employs in Table 1.1. These subsystems are driven by control systems as shown in the diagram of Fig. 1.1. The control system is hosted on a PC running Windows, using a server program that receives instructions and returns scan data using TCP/IP socket communications with a client computer (see Chapter 2). We anticipate that the client program will be written in IDL.

Table 1.1: STXM V and Cryo II microscope devices.

Name	Description	STXM V	Cryo II
XPZT	X sample piezo	Digital feedback from Agilent interferometer to Delta Tau controller (PI analog servo loop off)	Analog feedback from capacitance micrometer to PI piezo controller (PI analog servo loop on)
YPZT	Y sample piezo	Digital feedback from Agilent interferometer to Delta Tau controller (PI analog servo loop off)	Analog feedback from capacitance micrometer to PI piezo controller (PI analog servo loop on)
XSTG	X sample stepper stage	Driven by Newport MM-3000 via GPIB	Same as STXM V
YSTG	Y sample stepper stage	Driven by Newport MM-3000 via GPIB	Same as STXM V
ZSTG	Z sample stepper stage	Digital feedback from Agilent interferometer plus ZSTG encoder to Delta Tau controller and ACS stepper driver	ZSTG encoder to Delta Tau controller and ACS stepper driver
XDET	X detector stepper stage	Driven by Newport MM-3000 via GPIB	Same as STXM V
YDET	Y detector stepper stage	Driven by Newport MM-3000 via GPIB	Same as STXM V
ZDET	Z detector stepper stage	Driven by Newport MM-3000 via GPIB	Same as STXM V
ZOSA	Z order sorting aperture stage	Driven by Newport MM-3000 via GPIB	Does not exist