Automatic annular laser trapping: a system for high-throughput sperm analysis and sorting.

An automatic microscope system is designed to study the response of sperm motility to an annular laser trap. A continuous annular laser trap provides a parallel way to analyze and sort sperm based on their motility and to study the effects of laser radiation, optical force and external obstacles. In the described automatic microscope system, the phase contrast images of swimming sperm are digitized to the computer at video rates. The microscope stage is controlled in real-time to relocate the sperm of interest to the annular trap with a normal or tangential entering angle. The sperm is continuously tracked and the swimming behavior is identified. Using this system, parallel sorting on human and gorilla sperm are achieved and threshold power levels separating the "fast" group and the "slow" group are compared for those two species.