The spatial resolution of an OTR monitor, widely used for electron beam profile diagnostics, is determined by the resolution of the optical system and by the Point Spread Function (PSF) representing the single electron image. In the image plane, the PSF has a typical lobe-shape distribution with an inter-peak distance depending on wavelength and lens aperture ratio . For a beam with a transverse rms size smaller than the distance, the reconstruction of the beam profile has several difficulties [2, 3]. We propose to reduce the PSF contribution and to improve the spatial resolution of an OTR monitor simply by rotating the lens optical axis with respect to the specular reflection direction. If the difference between the rotational angle and the lens aperture is much larger than the inverse Lorentz factor, the PSF has a Gaussian-like distribution which matches practically with the Airy distribution. Thus the resolution depends on wavelength and lens aperture. In principle, for lens apertures in the order of 0.1 rad such an approach should allow to measure beam sizes comparable to the wavelength of observation, using a simple deconvolution procedure for the measured image and the PSF.