Previous tests on fighter plane-style cockpit canopies were problematic in that: a) debris impacting the canopy can rebound high into the air, presenting a safety risk to other cars and spectators, and b) accessing an injured driver in the event of an accident could prove highly difficult.
Next month the FIA will test some alternative solutions designed to improve protection from flying debris whilst also providing easy cockpit access. Among them is this concept, the result of a Mercedes study.
As the video shows, the halo-shaped hoop could stop certain types of debris from reaching the driver, whilst the hinged locking mechanism means it can quickly be removed for easy access. The proximity of the single, central strut to the driver is such that it should have minimal effect on visibility.