A photo-detector device may include a substrate having a bottom surface. The photo-detector device may further include a photocell secured to the bottom surface of the substrate. The photo-detector device may further include a metallic block having a top portion secured to a bottom surface of the substrate to enclose the photocell, wherein an opening is formed within the metallic block that extends from the top portion of the metallic block to a bottom portion of the metallic block to form an aperture for light to travel through the metallic block to the photocell. The photo-detector device may further include a member insertable into the metallic block to vary an open area of the aperture.