We examine and optimize the image quality of a laser recorder based on a multi-beam acousto-optical modulator producing a vertical fan of beams and a light deflector for scanning the beams horizontally. Besides the first-order scattered image-forming raster beams, some ‘parasitic’ beams due to threephonon scattering are also generated in the modulator. These beams interfere with the raster beams in the image plane of the recorder and give rise to spatial fluctuations of the exposure recorded along a line. We show that the horizontal distributionẼ(x) of the total energy incident on a vertical line is given by a sum over differences of the optical frequencies of the different beams, where each term is the product of the number of intermodulations at the given frequency, a cosinusoidal factor and a ‘noise transfer function’ depending only on the system parameters and the spatial frequency. We introduce a SNR defined as reciprocal of the relative RMS variation ofẼ(x) and evaluate its dependence on the system parameters and the acoustic carrier frequencies. We minimize the effect of intermodulations by finding sets of carrier frequencies that maximize the RMS and the minimum of the intermodulation frequencies respectively, and we calculate numerically the SNR for different distributions of acoustic frequencies.