A line of goniometers from Opto-Sigma Corp. offers rotation of an object or sample on a point in space without obscuring the incident beam. They simplify adjustment without the need for bulky mounts within the area of the element itself. One or two axes of rotation near the same point are available, and by stacking two axes together, the points of rotation coincide. Travel ranges from 20 to 40° with a scale indicating the angle from horizontal. Inch and metric hole mountings are available in 65- and 40-mm sizes. A locking mechanism is available to hold the unit in position.