Suggested beads for widefield PSF acquisitionRecording beads is a necessary first step to distill an experimental PSF. For Widefield microscopes, the following fluorescent beads were used with good results.
TetraSpeck 0.2 µm beads (fluorescent blue/green/orange/red, cat. ref. T-7280) from Life Technologies - Molecular Probes can be used, for example.
Tetraspeck microspheres are stained throughout with four different fluorescent dyes, yielding beads that each display four well-separated excitation/emission peaks: 365/430 nm (blue), 505/515 nm (green), 560/580 nm (orange) and 660/680 nm (dark red).
This kind of multicolor beads are very useful to calibrate also the Color Shift.