Rifle mounted optical unit

A warning unit for attachment to a handheld firearm, the warning unit comprising:

• attachment means for attachment to a firearm,
• a light source,
• expansion optics for expanding a beam of light emitted by the light source,
• divergence optics for controlling an amount of divergence of the beam emitted by the light source,
• a controller for controlling the extent to which the expansion optics expand the beam of light and for controlling the extent to which the divergence optics impose a divergence on the beam of light,
• input means actuatable by a user's hand to enable selection of a mode of operation of the warning unit, the warning unit being capable of being operated in at least a narrow divergence mode, and a wide divergence mode,
• wherein,
• in the narrow divergence mode, the controller is operable to cause the expansion optics to reduce the extent to which the beam is expanded and to cause the divergence optics to reduce the extent to which the beam of light diverges, to thereby cause the warning unit to emit a beam of light of a lower divergence than in the wide divergence mode.