The SL101.6BCH Gimbal Optical Mount is a true gimbal mount for high-resolution azimuth and elevation adjustment of 4 inch (101.6 mm) diameter mirrors and beamsplitters. The fixed rotational axes intersect at the front surface of the optic, allowing simple, non-coupled rotation without translation. The gimbal design also greatly reduces beam wander and optical path-length changes. These mounts are designed for maximum clear aperture of the transmitted beam at a 45° incident angle. SL Mounts are designed for a single nominal optical diameter for positive, made-to-fit three-point mounting inside the gimbal body. The base plate can be mounted in two places which allows you to convert between right-hand and left-hand operation. SL Series Mounts are configured with a base plate and riser (if required) for a nominal 50 or 75 mm optical axis height. Riser blocks of 25 mm and 50 mm may be placed in any combination beneath the base plate to achieve any optical axis height (>75) which is a multiple of 25 mm. For continuously variable height adjustment we recommend the ECN-80 elevator base. BHC Lockable Adjustment Screws lock the optic in position to prevent inadvertent misadjustment.