In this article we show that a single transparent wedge or a plate with a wedge part can be used bostik universal primer pro as a very simple and useful interferometer with numerous applications.This interferometer permits to modulate phase distribution on interference fringes to evaluate quantitatively the parallelism of a light beam and aberration of a wavefront, to quadruple topical ointment for dogs specify the spectral line shape in a wide range, to measure the light wavelength and refractive indices of solids and liquids.In addition, it provides suitable beams for holographic study of phase objects and fabrication of diffraction gratings.