Patent ID: 7616309

Claim:
A device for the positioning of optical elements with retractable stop enabling accurate positioning of an optical element selected among a plurality of optical elements, including: a stand ( 1 ); a turret ( 2 ) fitted with an element holder ( 3 ) carrying said plurality of optical elements, and with a disc ( 4 ) integral with the element holder ( 3 ), said disc ( 4 ) being a ratchet wheel having a peripheral surface ( 5 ) fitted with a plurality of blocking means ( 6 ), each blocking means ( 6 ) corresponding to an optical element, a motor ( 7 ) capable of driving said disc ( 4 ) in rotation relative to said stand ( 1 ) around a first axis in a so-called forward direction and in a reverse direction; and, a crash stop ( 9 ) bearing against the peripheral surface of the disc ( 5 ) and capable of retracting by moving around a second axis when actuating said motor ( 7 ) for driving the disc ( 4 ) in the forward direction, said crash stop ( 9 ) being capable of engaging with a blocking means ( 6 ) so as to block said disc ( 4 ) in position when actuating the motor ( 7 ) for driving the disc ( 4 ) in the opposite direction, characterised in that the crash stop ( 9 ) contains an anti-friction element ( 13 ) in contact with the peripheral surface ( 5 ) of the ratchet wheel so that the retractable stop ( 9 ) moves according to the contour of the peripheral surface ( 5 ) of the ratchet wheel without any friction.