“Infinity Optics” refers to the concept of a beam path with parallel rays between the objective and the tube lens of a microscope. Flat optical components can be brought into this “Infinity Space” without influencing image formation, which is critical for the utilization of contrast methods such as DIC
or fluorescence. Modern microscopy techniques require the addition of multiple optical instruments, such as light sources or laser devices, into the infinite light path. Different approaches to fulfill this need have emerged and are described here.