US Patent 10488156 Optical system accessory with cant indication

An electronic indicator accessory may be coupled to a standard scope, which is in turn coupled to a shooting device, to indicate whether the scope is canted. The indicator may be visual, haptic, or aural. If visual, the visual indicator may include one or more LEDs positioned on the periphery of the field of view, on an accessory body attached to the scope. The accessory body may be coupled near either the ocular or objective lens of the scope. The LEDs are coupled to a microprocessor which is, in turn, coupled to a solid-state electronic inclinometer that is incorporated into the internal structure of the optical system. The microprocessor is configured to selectively illuminate one or more of the visual indicators based on the output of the inclinometer, thereby indicating how the reticle is canted, if at all.