Novel printing techniques for optical elements produce characteristics in these optical elements which can sometimes not be resolved with classic testing or imaging methods. As highly individualized components often have a significant cost associated with them, destructive methods are unwanted. For this work, Scanning Laser Optical Tomography (SLOT) is considered to overcome these challenges and provide knowledge and data which would otherwise not be accessible. SLOT is directly compared to µCT which is often the go-to imaging modality for small, printed optics. Advantages such as the possibility to measure fluorescence with volumetric resolution are presented in this work in the application of a functionalized silicone waveguide. Interactions between the excitation light and the sample are also measured in SLOT in form of absorption. The importance of absorption is highlighted with the example of a 3D printed glass block which has light refractive layers that are invisible in µCT measurements. SLOT should be considered as a quality control tool by scientists and manufactures of printed optical elements as it has many advantages over µCT.