The present invention provides a chemiluminescence detector (100), which comprises an image capture device (110) sensitive to chemiluminescence located within a container (120). The container has an array of apertures (130) located in a field of view of the image capture device, and each aperture is defined by a through-bore in a wall of the container. The exterior of the container is engagable with a plurality of sample holders (200), each sample holder being in alignment with a respective aperture when engaged with the exterior of the container. The passage of light into the container through each aperture is restrictable by a closure device (140), passage of light into the container through the apertures is thereby controllable.
