Three-dimensional laser-scanning confocal reflecting microscope for multicolor single-molecule imaging at 1.5 K

•3D laser-scanning confocal single-molecule fluorescence microscope was built.•Single-component objective of reflecting design enabled multi-color imaging at 1.5 K.•Size of the image of single quantum dots was <1.2 times of the diffraction limit.•3D co-localization precision was 3nm in x, y and 18nm in z directions.