A monolithic frame for optics used in interferometers where the material of the monolithic frame may have a substantially different coefficient of thermal expansion from the beamsplitter and compensator without warping, bending or distorting the optics. This is accomplished through providing a securing apparatus holding the optics in place while isolating the expansion thereof from the expansion of the frame. Stability in optical alignment is therefore achieved without requiring a single material or materials of essentially identical coefficients of thermal expansion. The present invention provides stability in situations where it is not possible to utilize a single material for every component of the interferometer.