Method and a device for positioning an element in an optical system
View Patent ↗The disclosure generally relates to methods, devices, systems and components configured to position an element in a lens assembly, such as a lens assembly for microlithography, in which the element to be positioned is moved from an actual position to a target position via at least one actuator, and in which at least the positioning movement of the actuator is superimposed with an oscillating movement.
1. A method, comprising:
using an actuator to move an element from a first position to a target position by a positioning movement;
using a control unit to generate an oscillation; and
superimposing the positioning movement with an oscillating movement generated by the oscillation,
wherein:
the element configured to be used in an optical device for microlithography; and
the oscillating movement is changed during the positioning movement, after the positioning movement, or both.
2. A method according to claim 1 , wherein the element is moved incrementally or continuously.
3. A method according to claim 2 , wherein the element is moved with different movement patterns that are performed in sequence.
4. A method according to claim 1 , wherein the amplitude of the oscillating movement is changed.
5. A method according to claim 4 , wherein the amplitude of the oscillating movement is reduced when approaching the target position, and the amplitude is approximately equal to zero or less at the target position.
6. A method according to claim 1 , wherein the frequency of the oscillating movement is changed.
7. A method according to claim 6 , wherein the frequency is adjusted during the progressing approach to the target position.
8. A method according to claim 1 , wherein the form of the oscillating movement is changed.
9. A method according to claim 1 , wherein the form of the oscillating movement is selected from the group consisting of sine-shaped oscillating movements, triangle-shaped oscillating movements, saw tooth-shaped oscillating movements and rectangular-shaped oscillating movements oscillations.
10. A method according to claim 1 , wherein the movement of the actuator indirectly leads to the movement of the element.
11. A method according to claim 1 , wherein the actuator is selected from the group consisting of pressure controllers, valves, electric motors, electric magnets, piezoelectric components, and combinations thereof.
12. A method according to claim 1 , wherein the control signal for the actuator is superimposed with an oscillation.
13. A method according to claim 1 , wherein the elements, which can be positioned, are selected from a group comprising optical lenses, mirrors, prism, apertures, structured plates, and generally replaceable elements.