OPTICAL ELEMENT AND METHOD FOR OPERATING AN OPTICAL ELEMENT

1 . Optical element ( 1 ) comprising a first window ( 21 ) and a second window ( 22 ), wherein the first window ( 21 ) is connected to the second window ( 22 ) by an elastic membrane ( 41 ) such that the first window ( 21 ), the second window ( 22 ) and the membrane ( 41 ) enclose a deformable, sealed volume ( 42 ), which is filled with a fluid, wherein at least one first actuator ( 51 ) is arranged to tilt the first window ( 21 ) with respect to the second window ( 22 ) around a first tilting axis ( 81 ) in a first direction, wherein the first actuator ( 51 ) comprises a Shape Memory Alloy and has the shape of a wire.

2 . Optical element ( 1 ) according to claim 1 , wherein at least one first resetting element ( 61 ) comprises the Shape Memory Alloy and has the shape of a wire, wherein the first resetting element ( 61 ) is arranged to tilt the first window ( 21 ) in a first counter direction, wherein the first counter direction is opposed to the first direction.

3 . Optical element ( 1 ) according to claim 1 , wherein the first tilting axis ( 81 ) extends parallel to a main extension plane of the first window ( 21 ) and either along a first geometric axis ( 91 ) of the sealed volume ( 42 ) as seen in a top view along an optical axis of the optical element ( 1 ), or through a first attachment point ( 33 ) of the first actuator ( 51 ) to a top shaper ( 31 ), wherein the top shaper ( 31 ) is connected to the first window ( 21 ).

4 . Optical element ( 1 ) according to claim 1 , wherein at least one second actuator ( 52 ) is arranged to tilt the second window ( 22 ) with respect to the first window ( 21 ) around a second tilting axis ( 82 ) in a second direction, wherein a second actuator ( 52 ) comprises the Shape Memory Alloy and has the shape of a wire.

5 . Optical element ( 1 ) according to claim 4 , wherein at least one second resetting element ( 62 ) comprises the Shape Memory Alloy and has the shape of a wire, wherein the second resetting element ( 62 ) is arranged to tilt the second window ( 22 ) in a second counter direction, wherein the second counter direction is opposed to the second direction.

6 . Optical element ( 1 ) according to claim 4 , wherein the second tilting axis ( 82 ) extends obliquely with respect to the first tilting axis ( 81 ) and along a main extension plane of the second window ( 22 ) and either along a geometric axis ( 91 ) of the sealed volume ( 42 ) as seen in a top view along an optical axis of the optical element ( 1 ) or through a second attachment point ( 34 ) of the second actuator ( 52 ) to a bottom shaper ( 32 ), wherein the bottom shaper ( 32 ) is connected to the second window ( 22 ).

7 . Optical element ( 1 ) according to claim 1 , wherein a third resetting element ( 63 ) is arranged to tilt the first window ( 21 ) in a third counter direction, wherein the third counter direction is opposed to the first direction and/or is arranged to tilt the second window ( 22 ) in a fourth counter direction, wherein the fourth counter direction is opposed to the second direction, wherein the third resetting element ( 63 ) comprises at least one of the following:

the elastic membrane ( 41 ),

at least one resetting spring ( 65 ),

at least one resetting magnet ( 64 ).

8 . Optical element ( 1 ) according to claim 3 , wherein a mount ( 7 ) provides at least one first bearing for the top shaper ( 31 ) to define the first tilting axis ( 81 ), and/or provides at least one second bearing for the bottom shaper ( 32 ) to define the second tilting axis ( 82 ).

9 . Optical element ( 1 ) according to claim 6 , wherein the top shaper ( 31 ) and the bottom shaper ( 32 ) are connected by the first actuator ( 51 ) or by the second actuator ( 52 ).

10 . Method for operating an optical element ( 1 ) according to claim 1 , wherein

a Shape Memory Alloy of at least one first actuator ( 51 ) is heated up by supplying current,

once a transition temperature is reached, the first actuator ( 51 ) contracts, and

the contraction tilts the first window ( 21 ) with respect to the second window ( 22 ) around a first tilting axis ( 81 ) in a first direction.

11 . Method according to claim 10 , wherein

a Shape Memory Alloy of at least one second actuator ( 52 ) is heated up by supplying current,

once a transition temperature is reached, the second actuator ( 52 ) contracts, and

the contraction tilts the second window ( 22 ) with respect to the first window ( 21 ) around a second tilting axis ( 82 ) in a second direction.

12 . Method according to claim 10 , wherein the transition temperature of the first actuator ( 51 ) is 80° C., preferably 90° C., wherein the first actuator ( 51 ) contracts along its main extension direction by at least 2%, preferably by at least 3%, and/or wherein the transition temperature of the second actuator ( 52 ) is 80° C., preferably 90° C., wherein the second actuator ( 52 ) contracts along its main extension direction by at least 2%, preferably by at least 3%.

13 . Method according to claim 10 , wherein

the first actuator ( 51 ) cools down deceeding the transition temperature, and

a third resetting element ( 63 ) tilts the first window ( 21 ) in a third counter direction with the third counter direction being opposed to the first direction, and/or

the second actuator ( 52 ) cools down deceeding the transition temperature,

the third resetting element ( 63 ) tilts the second window ( 22 ) in a fourth counter direction with the fourth counter direction being opposed to the second direction.

14 . Method according to claim 10 , wherein

the first actuator ( 51 ) cools down deceeding the transition temperature,

a Shape Memory Alloy of a first resetting element ( 61 ) is heated up by supplying current,

once a transition temperature is reached, the first resetting element ( 61 ) contracts, and

the first resetting element ( 61 ) tilts the first window ( 21 ) in a first counter direction with the first counter direction being opposed to the first direction, and/or

the second actuator ( 52 ) cools down deceeding the transition temperature,

a Shape Memory Alloy of a second resetting element ( 62 ) is heated up by supplying current,

once a transition temperature is reached, the second resetting element ( 62 ) contracts, and

the second resetting element ( 62 ) tilts the second window ( 22 ) in a second counter direction with the second counter direction being opposed to the second direction.