Abstract: A chemiluminescence analyzer determines the level of chemiluminescence of a specimen. The chemiluminescence analyzer includes a light detection chamber for containing the specimen to be analyzed. The light detection chamber includes a chamber access device, for allowing the positioning of the specimen within the light detection chamber, and a shutter device. The shutter device and the chamber access device are configured to each have an open position and a closed position. A light detector is positioned behind the shutter device. When the shutter device is in the open position, the light detector detects light within the light detection chamber. An interlock assembly is interfaced with the shutter device and the chamber access device, such that the interlock assembly prevents the shutter device and the chamber access device from being simultaneously opened.