A document validator comprising a light pipe assembly comprising: a first light input port (234a, 234b, 1234) at a first end of the light pipe assembly; a light emitting surface (242, 402, 702) that extends substantially from the first end to a second end of the light pipe assembly; a plurality of surface features (402, 404a-404c, 704a-704g) in the light emitting surface (242, 402, 702), wherein each surface feature (402, 404a-404c, 704a-704g) defines a first internally reflective boundary (650a-c, 654a-c) at a far end of the surface feature (402, 404a-404c, 704a-704g) relative to the first light input port (234a, 234b, 1234), wherein light that enters the first input port (234a, 234b, 1234) is directed to the first internally reflective boundaries (650a-c, 654a-c); one or more reflective surfaces arranged to reflect light from the first internally reflective boundaries (650a-c, 654a-c) through the light emitting surface (242, 402, 702), wherein the first internally reflective boundaries (650a-c, 654a-c) vary in size across the light emitting surface (242, 402, 702); and a second light input port (234a, 234b, 1234) at the second end of the light pipe assembly, wherein each surface feature (402, 404a-404c, 704a-704g) in the light emitting surface (242, 402, 702) defines a second internally reflective boundary (650a-c, 654a-c) at a far end of the surface feature (402, 404a-404c, 704a-704g) relative to the second light input port (234a, 234b, 1234), wherein light that enters the second light input port (234a, 234b, 1234) is directed to the second internally reflective boundaries (650a-c, 654a-c), wherein the one or more reflective surfaces reflect light from the second internally reflective boundaries (650a-c, 654a-c) through the light emitting surface (242, 402, 702), and wherein the second internally reflective boundaries (650a-c, 654a-c) vary in size across the light emitting surface (242, 402, 702). a first light input port (234a, 234b, 1234) at a first end of the light pipe assembly; a light emitting surface (242, 402, 702) that extends substantially from the first end to a second end of the light pipe assembly; a plurality of surface features (402, 404a-404c, 704a-704g) in the light emitting surface (242, 402, 702), wherein each surface feature (402, 404a-404c, 704a-704g) defines a first internally reflective boundary (650a-c, 654a-c) at a far end of the surface feature (402, 404a-404c, 704a-704g) relative to the first light input port (234a, 234b, 1234), wherein light that enters the first input port (234a, 234b, 1234) is directed to the first internally reflective boundaries (650a-c, 654a-c); one or more reflective surfaces arranged to reflect light from the first internally reflective boundaries (650a-c, 654a-c) through the light emitting surface (242, 402, 702), wherein the first internally reflective boundaries (650a-c, 654a-c) vary in size across the light emitting surface (242, 402, 702); and a second light input port (234a, 234b, 1234) at the second end of the light pipe assembly, wherein each surface feature (402, 404a-404c, 704a-704g) in the light emitting surface (242, 402, 702) defines a second internally reflective boundary (650a-c, 654a-c) at a far end of the surface feature (402, 404a-404c, 704a-704g) relative to the second light input port (234a, 234b, 1234), wherein light that enters the second light input port (234a, 234b, 1234) is directed to the second internally reflective boundaries (650a-c, 654a-c), wherein the one or more reflective surfaces reflect light from the second internally reflective boundaries (650a-c, 654a-c) through the light emitting surface (242, 402, 702), and wherein the second internally reflective boundaries (650a-c, 654a-c) vary in size across the light emitting surface (242, 402, 702).