Linear moving carriage

A rotary system for constraining to a rectilinear movement a movement of an element such as a moving mirror of a Michelson interferometer, comprising:

• a support;
• first, second, third and fourth primary sides;
• pivot means interconnecting said primary sides to form a first parallelogram with said first and second primary sides parallel and said third and fourth primary sides parallel and rotatable in-plane with respect to said second primary side;
• means fixing said first primary side to said support;
• first, second, third and fourth secondary sides;
• pivot means interconnecting said secondary sides to form a second parallelogram with said first and second secondary sides parallel and said third and fourth secondary sides parallel and rotatable in-plane with respect to said secondary side;
• and said second secondary side fixed to said second primary side so as to maintain a fixed relative orientation therebetween;
• a flexible constraining member having a first end connected to said first parallelogram and a second end connected to said second parallelogram, said flexible constraining member adapted to produce one sense of said in-plane rotation of said third and fourth secondary sides in response to an opposite sense of said in-plane rotation of said third and fourth primary sides;
• and
• drive means for producing said in-plane rotation of said third and fourth legs.