Abstract: A light barrel configured to filter out stray light of a test light includes a casing and a number of light shield plates arranged within the casing. The light shield plates are parallel to each other and arranged within the casing along a direction in which the light source emits the test light. Each of the light shield plates defines a through hole for light from the test light to pass through. The through holes of the light shield plates are a same size and aligned. The light shield plates sequentially filter out stray light that does not pass through the through holes.

Abstract: A light barrel configured to filter out stray light of a test light includes a casing and a number of light shield plates arranged within the casing. The light shield plates are parallel to each other and arranged within the casing along a direction in which the light source emits the test light. Each of the light shield plates defines a through hole for light from the test light to pass through. The through holes of the light shield plates are a same size and aligned. The light shield plates sequentially filter out stray light that does not pass through the through holes.

Abstract: A surface light source device and system for monitoring uniformity of brightness of the device are disclosed, the device includes a light source unit; a light guide plate, and at least one light uniformity plate. The light guide plate includes a light incident surface and a light emitting surface, the light incident surface is disposed in a light emitting direction of the light source unit; and the light incident surface is disposed in a light emitting direction of the light source unit. The at least one light uniformity plate comprises a light receiving surface facing the light emitting surface, the light receiving surface is defined with a plurality of zones, and each zone is provided with a photosensitive element which senses and measures the brightness of light. A method of operating the monitoring system is also disclosed.