Abstract: A light beam chopping or intercepting apparatus capable of repeatedly and sequentially intercepting and passing a light beam at a regular cycle by rotatively vibrating a disk-shaped vibrating body in a casing, wherein the disk-shaped vibrating body and the casing have transparent windows through which the light beam is passed. A detection coil and an excitation coil are mounted on the inner wall of the casing, in respective positions opposite to two magnets provided on the disk-shaped vibrating body. A transistor circuit having these coils on its base side and on its collector side, respectively, is operated as the vibration generating source. Coiled springs installed between the rotation center shaft and the casing provide the repeating vibration force. The number of vibrations can be arbitrarily changed, for example, by adjusting the spring constants of the coil springs.