In current virtual environment systems, the stereoscopic images presented in a head-mounted display are far from optimal. The aim is to achieve orthostereoscopy, which roughly means images should `behave as in real life.' A theoretical model of stereoscopic optics was used to implement a test and optimization system. Tests were devised to analyze the importance of many stereoscopy related parameters. The system's capability to independently set these parameters allows an optimization of the stereoscopic images, given the limitations of the display device used.