Tilting the specimen

When recording a tilt series in the cryo STXM, you need a strip aperture as an OSA. Our strip apertures are made by Fullam. They have a width of 0.5 mm, and aperture sizes of $70~\mu$m and $37.5\mu$m, respectively. The strip apertures are mounted on an OSA holder with blade-shaped tip. The small width of the OSA and OSA holder allow rotation of the specimen around the OSA and OSA holder.

To tilt the specimen, the specimen holder is rotated with the rotary stage on the airlock. A worm drive is used to rotate the whole airlock with the specimen holder in it. A scale shows the tilting angle in $1^{\circ}$ steps.

Tilting should be done with care since some of the holders we use -- particularly the LBL cryo holder -- have a rather fragile tip. Therefore, the specimen holder should be lifted slightly off the socket on the scanning stage before rotating, particularly when tilting by large angles. To prevent the specimen holder to touch the OSA, it is recommended to turn on the light in the vacuum chamber and observe the relative position of specimen holder and OSA with the telescope on top of the chamber.