A biological sample such as a tissue section is stained with one or more quantum dots and possibly other fluorophores. A foot link includes a rearward portion that is constrained to move in an orbital path approximately parallel to the longitudinal axis and a forward portion that reciprocally engages the guide track. Since the microstrip-type BALUN is realized by a microstrip line which is a distributed constant line, the microstrip-type BALUN has an excellent performance even for high-frequency signals.