Abstract: The present invention discloses an improved apparatus for performing safe and reliable built-in testing (BIT) of a laser initiated ordnance device. The system transmits light energy from a laser through optical fibers to achieve initiation of pyrotechnic or explosive charges and other ordnance. In the preferred embodiment, a separate BIT return fiber is included in the system in addition to the energy transmission fiber. The invention also incorporates a "telescope" comprising a pair of gradient-index (GRIN) rod lenses in series to first collimate and then reconcentrate light emitted by the energy transmitting fiber, while reflecting part of the light to an image at the face of the BIT fiber. Alternatively, an arrangement using a pair of aspheric silica lenses can be substituted for the GRIN lenses. The fraction of the light reflected to the BIT fiber can be controlled by specifying the reflectance at one of the lens end surfaces.