Thursday, August 22, 2013

Nanpositioning System Interface

There are multiple ways in which to communicate with a nanopositioning controller. A common way to command a stage is by using the standard BNC analog inputs of the controller.  Each channel is equipped with analog control and sensor monitor BNC connectors. A voltage range of -10V to 10V is calibrated so that the maximum travel distance is used. Stages can also be calibrated for other input ranges as well. nPoint controllers have 20 bit resolution allowing for sub-nanometer control within the analog input range. 

DAQ (data acquisition) cards are often used in conjunction with a PC to send analog signals to the controller.  There are a variety of these cards available from multiple vendors. National Instruments is a well known provider of DAQ cards.  They also have cards that can be used for a variety of digital system interfaces.

The system can also be interfaced via USB, Digital I/O, PFM, or high speed parallel port.  The nPoint USB interface uses FTDI drivers compatible with many programming languages.  The user can perform a variety of functions via the USB interface such as commanding position, reading the actual position, (sensor signal) and changing control parameters when required. Labview and DLL drivers facilitate integration with a variety of applications. The digital I/O can assign different triggering functions to the 9-pin interface through the front panel software facilitating inegration with other instruments and the customization of experiments. The PFM (pulse frequency modulation) interface is designed to receive position commands and output position data in real-time. The position command data is received as standard pulse/direction differential signals. The position monitor data is output as standard differential quadrature signals. The PFM interface facilitates the integration of the nPoint controller with industry-standard motion controllers. A high speed interface offers communication with the controller at full loop speed. This allows the user to set the position and read sensor data for up to six channels every 24 microseconds at 20 bit resolution. Providing the best overall digital signal capabilities to a nPoint system.

nPoint also provides AFM interface capabilities to allow for closed-loop scanner upgrades for existing Agilent, Ambios, and Veeco AFMs.  These come in a "plug and play" type kit where little changes for the user with the AFM software, but allows for longer travel ranges and closed-loop control of an nPoint nanopositioning system.

Custom interface options are available for nPoint controllers.  Please inquire with any specific questions or if interested in setting up a custom system interface project with nPoint.