DLSSWU stands for Directional Light Sheet of Selected Wavelength Unit, which is the core of a TU Wien PCT patent (WO2022129596A1- Optical Device for controlling a light beam). DLSSWU can reshape a symmetrical small laser beam into super-thin parfocal carpets of light of selected wavelengths (light sheets) with limited diffraction. Using DLSSWU, we aim at the development and implementation of a new high-resolution imaging technique that can be used directly in diagnostics in human pathology. The technique provides 3D images of large pieces of biological samples such as the brain, spinal cords, and tumors with cellular resolution. Current methods in tissue diagnostics are restricted to the analysis of a small number of representative two-dimensional tissue slices. Therefore, since most biological tissues form complex three-dimensional structures, the relevant pathologies for three-dimensional deep examination with high resolution of tissue structure in accurate diagnostic or forensic, are sometimes missed. Therefore, a fast reliable imaging method for samples such as tumors in their complete spatial 3D context would be an invaluable asset. Our preliminary results from the much-simplified system published in 2020 (Nature series/Scientific Reports: 3D histopathology of human tumors by fast clearing and ultramicroscopy) confirmed the possibility of 3D imaging of fully intact human tumors using light sheet imaging technology setups utilizing Meso-aspheric optical elements. In comparison with standard histology, we have proved that our Meso-aspheric light sheet approach is capable of providing image malignancies in 3D from large tissue blocks with cellular resolution. The specific structures of novel optical elements designed for DLSSWU presented in WO2022129596A1 are expected to improve the light sheet optical characteristics that control directly the image quality substantially. Our simulation has already confirmed this prediction. Meanwhile, we have developed the required software for a computer-controlling system as well as deconvolution software for further improvement of images’ quality. We now plan to develop the prototype for this high-resolution imaging technique. This approach ultimately will lead to a faster, safer, and more informative visualization method of large biological samples such as human tumors and – ultimately - histologies of diseases in general. We are convinced that by developing our prototype and adjusting it to the needs of diagnostic pathology in the future true 3D routine histopathology might become an exciting reality.