Modeling of a monolithic twobeam interferometer with precise spatial fixation of a tunable interference grating

A monolithic (mirrorless) two-beam interferometer based on a beam-splitting cube equipped with a fixed photosensitive object is analytically investigated. The interferometer can perform broadband tuning of the spatial frequency of the being recorded interference grating. The initial light beam is fed into the cube by means of a movable mirror that simultaneously performs mutually conformed linear movement and angular movement, due to which the position of the initial beam on the input surface of the cube and the incidence angle on it also change in a conformed manner. As a result, the convergence angle of the partial beams formed in the beam-splitting cube changes together with the incidence angle, and the intersection point of their axes remains strictly immobile relative to the cube within the full range of tuning. The latter is achieved by a special design of the lever mechanism that controls the movement of the movable mirror. The tuning characteristics of the interferometer are calculated taking into account the diameter of the initial beam, and the profile of the inclined guide of the lever mechanism is found, which ensures spatial fixation of the interference grating. The intended purpose of the device is to quickly change the spatial frequency of the interference grating when recording diffraction gratings with different periods.