PNS MANUAL: operation / grating

Tuning the grating

Tuning the grating should not normally be necessary as the degree of "walk-off" is quite small, only about 1.2 pixels per angstrom. If you need to do it you should consult Nigel Douglas, John Hart or Gabe Bloxham.

Exchanging the grating

Currently we only have the 600g/mm gratings. Here are the instructions for accessing them, starting with a view of the end plate.

The outer screws mount the grating unit to the camera body. The inner screws hold the grating unit together (and should NOT normally be removed). Getting the grating unit out is awkward because there is nothing to grip it by. If you ever decide you want to do this frequently, it would pay to mount a handle. There are also two dowel pins that locate the grating unit, and these are awkward to disengage. If you do want to remove the grating unit, it would be wise to leave the two screws adjacent the dowels loosely in place until the dowels are disengaged. This will prevent the grating unit from suddenly collapsing onto the camera body when it comes free.

On 26-02-2003, the grating unit was removed, and the tension increased in the springs that apply pressure to the grating in the dispersion direction. This was accomplished by adding a second spring, and inserting plastic spacers into the spring-rod holes. The purpose of this was to keep the gratings from shifting about (hypothetical origin of the "clunk"). It's not yet known if this has succeeded, but there seem to be no ill effects.


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