On the use of electronic tilt sensors as angle encoders for synchrotron applications

We have tested several electrolytic tilt sensors produced by Applied Geomechanics, Inc. A pair of sensors were tested by mounting them on the Chi circle of a Huber 4 circle diffractometer. The angles were scanned in 1° intervals over a range of ±35°. In these tests the resolution was about ±5 μrad but the repeatability depended on angle and varied from 70 μrad (one standard deviation) at large angles to 7 μrad at small angles. This type of tilt sensor may be too slow (2–10 s settling time) as a primary angle encoder for a monochromator or diffractometer, but for a system run by stepping motors, they would prove quite useful as secondary angle encoders. Other models which have a narrower angular range would be useful in setting and tuning focusing mirrors.