The inner unit of Panasonic SF4B-*G Version 2 robust light curtain is fully protected with a thick metal case. Impact between the workpiece and the sensor is prevented by narrowing and deepening the exposed area of the sensing surface. The SF4B-G series light curtain is enclosed in a 5 mm (0.197 in) thick robust metal case, protecting the workpiece from various types of impact, such as collision or being stepped on. The robust light curtain can be used without an L-shape or U-shape guard, reducing installation and maintenance. The sensing surface is fully protected by narrowing and deepening the exposed area of the sensing surface. The seamless structure protects the sensor from being exposed to water. The cylindrical frame construction allows mechanical shock to dissipate upon impact, minimizing severe damage in the event of a collision. This unique design minimizes the possibility of beam axis misalignment and provides a safer workplace. The case is designed so that shock upon impact is dissipated alleviating potential damage to the workpiece in the event of a collision. The body has a alumite-treated case whereby paint does not stick to the workpiece in the event of a collision. The light curtain and the mounting bracket are firmly secured with just two bolts. The light curtain is situated in the center of the mounting bracket, preventing beam axis deviation. The dimple structure makes alignment easy to adjust.