Optical arrangement for generating a light sheet

The invention relates to an optical assembly comprising a light source for emitting a light beam and having optical elements for converting this light beam in the form of a light sheet (3), particularly suitable for illumination of individual layers of a three-dimensional sample (1) in the Selective plane illumination microscopy (SPIM). According to the invention means are provided for variation of the cross section of the light sheet (3) for varying the length of the light sheet (3) and / or for influencing the direction of the inside of the light sheet (3) extending individual radiation components to the sample with such an optical arrangement, directed. Thus, both the adjustment of the geometry of the light sheet (3) to the lighting requirements in the observation of the same sample plane is made possible with several different types of lenses as well as if necessary to achieve a reduction of shadows, which form within the observed specimen plane due to the lighting.