A pixel unit, comprising: a base, the base being provided with an installation space; a photodiode, the photodiode being installed in the installation space, and the photodiode comprising a red photodiode, a green photodiode, and a blue photodiode that are spaced from each other; and an optical splitter, the optical splitter being installed on the base, at least part of the optical splitter being located in the installation space, the optical splitter having a light-in surface, a first light-out surface, a second light-out surface and a third light-out surface, and the optical splitter being configured to disperse light entering the light-in surface and then emit the light from the first light-out surface, the second light-out surface and the third light-out surface, wherein the first light-out surface faces the red photodiode, the second light-out surface faces the green photodiode, and the third light-out surface faces the blue photodiode, wherein the base comprises: a bottom plate, a first lateral panel, a second lateral panel, a third lateral panel and a fourth lateral panel, the first lateral panel, the second lateral panel, the third lateral panel and the fourth lateral panel being successively connected into a ring shape, and the first lateral panel, the second lateral panel, the third lateral panel and the fourth lateral panel being respectively connected to edges of the bottom plate, the installation space is formed among the bottom plate, the first lateral panel, the second lateral panel, the third lateral panel and the fourth lateral panel, and the photodiode and the optical splitter are both installed in the installation space, characterized in that, the bottom plate, the first lateral panel and the third lateral panel are respectively provided with one of the red photodiode, the green photodiode and the blue photodiode. a base, the base being provided with an installation space; a photodiode, the photodiode being installed in the installation space, and the photodiode comprising a red photodiode, a green photodiode, and a blue photodiode that are spaced from each other; and an optical splitter, the optical splitter being installed on the base, at least part of the optical splitter being located in the installation space, the optical splitter having a light-in surface, a first light-out surface, a second light-out surface and a third light-out surface, and the optical splitter being configured to disperse light entering the light-in surface and then emit the light from the first light-out surface, the second light-out surface and the third light-out surface, wherein the first light-out surface faces the red photodiode, the second light-out surface faces the green photodiode, and the third light-out surface faces the blue photodiode, wherein the base comprises: a bottom plate, a first lateral panel, a second lateral panel, a third lateral panel and a fourth lateral panel, the first lateral panel, the second lateral panel, the third lateral panel and the fourth lateral panel being successively connected into a ring shape, and the first lateral panel, the second lateral panel, the third lateral panel and the fourth lateral panel being respectively connected to edges of the bottom plate, the installation space is formed among the bottom plate, the first lateral panel, the second lateral panel, the third lateral panel and the fourth lateral panel, and the photodiode and the optical splitter are both installed in the installation space, characterized in that, the bottom plate, the first lateral panel and the third lateral panel are respectively provided with one of the red photodiode, the green photodiode and the blue photodiode. a bottom plate, a first lateral panel, a second lateral panel, a third lateral panel and a fourth lateral panel, the first lateral panel, the second lateral panel, the third lateral panel and the fourth lateral panel being successively connected into a ring shape, and the first lateral panel, the second lateral panel, the third lateral panel and the fourth lateral panel being respectively connected to edges of the bottom plate, the installation space is formed among the bottom plate, the first lateral panel, the second lateral panel, the third lateral panel and the fourth lateral panel, and the photodiode and the optical splitter are both installed in the installation space, characterized in that, the bottom plate, the first lateral panel and the third lateral panel are respectively provided with one of the red photodiode, the green photodiode and the blue photodiode.