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Device Functions
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Using Pulsers
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Internals
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6.21 Light Chopper Functions

A module for a single computer controlled light chopper exists:

gg_chopper

Home-built light chopper(1), controlled by a data acquisition device, currently the National Instruments PCI-MIO-16E-1 DAQ card, group of G. Gescheidt, TU Graz

To use the module in an experiment put its name into the DEVICES section of the EDL script. Please note that the name of the module for the DAQ device (PCI-MIO-16E-1) must be listed before this module.

Unless a choppers frequency has already been set during the PREPARATIONS section the chopper will only start to rotate when a resonable rotation (sector) frequency is set by calling the function chopper_sector_frequency(). At the end of an experiment the chopper gets stopped automatically.

List of chopper functions:

`chopper_name()'

`chopper_sector_frequency()'

`chopper_create_trigger()'

Descriptions of chopper functions:

`chopper_name()'

Returns a string with the name of the chopper being used.

`chopper_sector_frequency()'

This function allows to either query or set the rotation speed of the chopper (or, to be exact, the inverse of the number of sectors of the chopper per second). When called without an argument the function returns the current frequency (0 Hz when the chopper is stopped). If called with an argument between 39.22 Hz and 200 Hz the chopper frequency gets set to this value (if it is not possible to set the frequency with an accuracy of at least 1% a warning is output, informing the user about the real sector frequency, which is also the value returned by the function). If the function is called with a zero or negative argument the chopper is stopped.

When called during the PREPARATIONS section of thr EDL script the choppers frequency is set to this value when the experiment is started.

`chopper_create_trigger()'

This function makes the electronics controlling the chopper create a TTL trigger pulse the next time the light path gets opened, e.g. to trigger an acquisition.

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This document was generated by Jens Thoms Toerring on September 6, 2017 using texi2html 1.82.