A ray detector substrate includes: photodetectors including first photodetectors and second photodetectors; and dimming portions including, at a side of each first photodetector away from a substrate, a respective first dimming portion, and, at a side of each second photodetector away from the substrate, a respective second dimming portion. A second scintillator layer is configured to convert part of rays into a first radiation fluorescence. A first scintillator layer is configured to convert another part of the rays into a second radiation fluorescence. The first dimming portion is configured to reflect the second radiation fluorescence, and to enable the first radiation fluorescence to pass through the first dimming portion to be detected by the first photodetector. The second dimming portion is configured to reflect the first radiation fluorescence, and to enable the second radiation fluorescence to pass through the second dimming portion to be detected by the second photodetector.