A polygon of a laser optical system is supported by a housing and requires precise alignment with respect to a base for proper operation of the optical system. A fixture has a base that is mounted for rotation about an axis. A plurality of adjustable pad assemblies are located between the base and the housing. Each pad assembly includes a mounting plate that is positioned on the base and a bushing that is secured to the housing. A compressible ring surrounds a surface on the plate that receives an adhesive. Pushers carried by the base engage the housing and urge the housing toward the base. The pushers are individually adjustable to control the position of the housing relative to the base about a plurality of axes. An optical instrument measures the angular position of the optical device on the housing and, when it is properly positioned, it is held until the adhesive cures to bond the mounting plate and bushing together.