M77781A
MS257
™ USB/RS232
MONOCHROMATOR AND SPECTROGRAPH
51
Motor Driven Slit Assembly
The 77722 Motor Driven Slit Assembly has continuously adjustable width from 4
µ
m to 2000
µ
m.
The slit height is 15 mm. The motor drive uses a micro-stepping motor and each step
corresponds to a 2
μm change in slit width. The slits are controlled directly by MS257. Each slit’s
width can be individually set or they can all be placed under the automatic control of MS257 in
order to maintain a constant bandpass at all wavelengths. The required bandpass can be
specified using the utility program, hand controller or terminal program.
Note that it is normal for some noise to come from the solenoid, even when the slit width is not
changing. The noise level will vary from between motorized slits. The solenoid will get slightly
warm when powered on.
When using the hand controller, the following needs to be kept in mind. Commanding the slit to
be a width which is an odd number will result in the width being adjusted to the next lower even
width. For example, a slit width entered as 7 um will result in the slit to be set to 6 um wide.
Commanding the slit to be 2 um wide (which is too narrow) will result in the slit width being set to
4 um. Commanding the slit to be 3000 um (which is too wide) will cause error message E0002 to
appear on the hand controller display.
Automatic control works well for a bandpass significantly larger than resolution. If accurate
bandpass value is of critical importance, one may want to experimentally determine proper slit
settings when working at bandpass values close to the instrument resolution.
Figure 18: Motorized Slit
