When light interacts with a scattering sample, the incident light is reduced - an effect referred to as light extinction. This renders some experimental problems. The example to the left shows three identical voxels containing a number of particles. However, despite being identical, the first voxel scatter more light than the last one because of light extinction.

Dual-SLIPI aims to quantify the sample based on how much it extincts light and not how well it scatters light which is the "normal" approach. This is done by viewing the sample at two positions and from two opposite sides simultaneously. By extracting the ratio between the images, the local extinction of light can be extracted.

The example to the left shows the difference between a conventional laser sheet-, SLIPI- and a dual-SLIPI measurement of a homogeneous sample. Only the dual-SLIPI case shows the homogeneity.