The LC-40-100 RN-DTC is currently in service with the Royal Navy. The sight is a unit power, solid glass, reflex collimator sight designed for the heavier direct fire small arms or cannons. It is designed for easy surveillance and target acquisition engagement. The solid glass optic means there is no need for maintenance and cannot mist up. This type of sight is an up to date replacement for traditional open or cartwheel sights. Because the graticule pattern is seen at infinity against the target the firers eye position is not constrained and can move sideways, up and down, fore and aft within wide enough limits to make tracking the target and shooting easy.
One advantage of the Ring Sight is its large aperture, 40 x 30 mm, making it the choice for pintle mounted gun where the firer wants the maximum eye freedom as he moves around the pintle. so the gunner does not have to position his eye precisely (up down, sideways and in and out) unlike conventional optical day and night sights which have limited eye freedom in all these directions.
The sight uses a reflex collimator with no magnification . It uses ambient light by day and for low light and in the dark the graticule is lit by an in-built LED array, always in place. The LED array is powered by two lithium thionyl chloride 1/2 AA batteries (giving an excellent temperature range) : the brightness is adjusted by the gunner to suit the conditions. This means that low ambient light can be enhanced when needed and that NVG can be used without affecting their control. The LC-40-100-NVG-RN-DTC is the latest design with improved piezoelectric switches to be used on 20 and 30 mm naval cannons.
The LC-40-100 can be fitted with interchangeable filters for use in bright sun, laser protection, etc.