62NG and 62SG Optical Encoders Grayhill 62NG and 62SG Optical Encoders satisfy the most common requirements for human interface encoders. The encoders are competitively priced and provide superior reliability and performance. The optically-coupled switching allows for the encoders to surpass one million rotational cycles offering superior durability over corresponding mechanical encoders. The 62NG and 62SG series encoders are an effective and competitive user interface solution.