Single Photon LSCM in the NIR Range

Abstract: In this thesis a near-infrared laser scanning confocal microscope (NIR-LSCM) is built to operate with optimal performance at 1550nm in combination with simultaneous LED light imaging at 970nm. For detection, a camera equipped with a complementary metal oxide semiconductor (CMOS) sensor and a superconducting nanowire single photon detector (SNSPD) are used for the LED part and the LSCM part, respectively. By using an SNSPD developed for operation in the NIR with a timing jitter of 19ps and a quantum efficiency (QE) of 85$\%$ instead of, for example, a photo-multiplier tube (PMT) or a single photon avalanche photo diode (SPAD), it has been demonstrated that limitations of existing systems can be reduced.  This thesis also demonstrates that it is possible to build a LSCM with commercially available optical components. It is also proved how important it is to consider the features of each optical component chosen as well as how all components work together as a system. Especially how important it is to consider lens coatings and splitting ratios for beamsplitters to realize a system with optimal performance for operation in the NIR. Thorough research in combination with a trial-and-error process was used to arrive at the final NIR-LSCM system setup presented in this thesis. As a final note, this thesis sheds light on some possible NIR-probes which are suitable for operation in combination with our system.