An apparatus for providing temperature-dependent movement of an optical element, the apparatus comprising: a moveable mount for the optical element; a guide configured to guide a movement of the moveable mount and a mount moving component having a first end attached to the moveable mount at a first attachment position on the moveable mount, and a second end attached to the guide at a second attachment position on the guide, wherein the apparatus is configured such that a difference in thermal contraction or thermal expansion between the mount moving component and the guide in response to a change in temperature of the apparatus causes the mount moving component to move the moveable mount relative to the guide, wherein the mount moving component is attached to the moveable mount such that a change in distance between the optical element when mounted on the movable mount and the second attachment position on the guide in response to the change in temperature of the apparatus is independent of the thermal contraction or thermal expansion of the guide in response to the change in temperature of the apparatus, wherein the moveable mount forms a first portion of a flexure mount and the guide forms a second portion of the flexure mount, wherein the apparatus is configured such that the difference in thermal contraction or thermal expansion between the mount moving component and the guide in response to a change in temperature of the apparatus causes the mount moving component to move the first portion of the flexure mount relative to the second portion of the flexure mount, wherein the mount moving component comprises a first rod (184-1a; 184-1b), and wherein a first end of at least a portion of the first rod (184-1a; 184-1b) is connected to the first portion of the flexure mount and a second end of the at least a portion of the first rod (184-1a; 184-1b) is connected to the second portion of the flexure mount such that a thermal expansion of the first rod (184-1a; 184-1b) causes the first portion of the flexure mount and the second portion of the flexure mount to move away from or towards each other. a moveable mount for the optical element; a guide configured to guide a movement of the moveable mount and a mount moving component having a first end attached to the moveable mount at a first attachment position on the moveable mount, and a second end attached to the guide at a second attachment position on the guide, wherein the apparatus is configured such that a difference in thermal contraction or thermal expansion between the mount moving component and the guide in response to a change in temperature of the apparatus causes the mount moving component to move the moveable mount relative to the guide, wherein the mount moving component is attached to the moveable mount such that a change in distance between the optical element when mounted on the movable mount and the second attachment position on the guide in response to the change in temperature of the apparatus is independent of the thermal contraction or thermal expansion of the guide in response to the change in temperature of the apparatus, wherein the moveable mount forms a first portion of a flexure mount and the guide forms a second portion of the flexure mount, wherein the apparatus is configured such that the difference in thermal contraction or thermal expansion between the mount moving component and the guide in response to a change in temperature of the apparatus causes the mount moving component to move the first portion of the flexure mount relative to the second portion of the flexure mount, wherein the mount moving component comprises a first rod (184-1a; 184-1b), and wherein a first end of at least a portion of the first rod (184-1a; 184-1b) is connected to the first portion of the flexure mount and a second end of the at least a portion of the first rod (184-1a; 184-1b) is connected to the second portion of the flexure mount such that a thermal expansion of the first rod (184-1a; 184-1b) causes the first portion of the flexure mount and the second portion of the flexure mount to move away from or towards each other.