Optical frame for checking distances rapidly, useful for sporting activities such as controlling football penalties and free kicks

摘要

Two rods (1,2) have collars (11,14,21,24) at their ends which enable light sources such as optical pens (3,4) to be aligned such that their beams (5,6) cross at a predetermined distance. The design may be varied to allow adjustment of the distance by a screw (13) working with an elastic element in the collar (11). Light switches (7,8) are included