A set of wedge plates required for setting up lateral shearing interferometer for laser beam collimation testing of various apertures has been suggested in order 10 obtain maximllm sensitivity in the detection of laser beam decollimation. The wedge angle of the plate may vary from an angle of 2.5 arc-sec to 60 arc-sec whereas the suitable thickness of the wedge plate may vary from 3 mm to 66 mm depending on the size of the laser beam wider test. As set of ten wedge plales is suggested for checking the laser beam decollimation of apertures varying from 3 mm to 100 mm.