Adaptive lens
The invention relates to a tunable lens where the optical power can be adjusted. The lens consists of a deformable, non-fluid lens body sandwiched between a thin, flexible membrane and transparent back window, and an actuator system serving to change the overall shape of the membrane and lens body. The membrane is pre-shaped to have a Sag or Sagittal of at least 10 μm so that the lens has a non-zero optical power when the actuator system is not activated. In order to achieve a large optical power range for the lens, the membrane should preferably be made of a material having a Young's modulus in the range 2-1.000 MPa.
1. An optical lens assembly comprising:
a transparent and flexible membrane, wherein said transparent and flexible membrane is formed in a material having a Young's modulus in the range between 2 MPa and 1,000 MPa;
a transparent back window;
a transparent, deformable, lens body sandwiched between said transparent back window and said transparent, flexible membrane to form a lens with an optical axis being normal to a surface part of said transparent back window, wherein said lens body comprises a polymer network of cross-linked or partly cross-linked polymers, and, wherein said lens body further comprises a miscible oil or combination of oils;
said transparent and flexible membrane being pre-shaped to impress a first overall shape to said transparent and flexible membrane and said non-fluid lens body, wherein with said first overall shape said lens has a substantial, non-zero first optical power;
a rigid frame configured to support a circumference of the membrane; and
an actuator system configured to apply a force to change the overall shape of the membrane and said lens body from the first overall shape to a second overall shape with which the lens has a different optical property;
wherein said actuator system comprises piezoelectric actuators on a surface of said transparent and flexible membrane,
wherein said back window has a planar surface facing the lens body, wherein said lens has a Sag of at least 10 μm when said actuator system is not activated, and
wherein said flexible membrane has a Sag between 10 and 500 μm and an aperture diameter between 1 and 60 mm.
2. The optical lens assembly according to claim 1 , wherein said flexible membrane has a thickness 5-30 μm.
3. The optical lens assembly according to claim 1 , wherein said non-fluid lens body has an elastic modulus larger than 300 Pa.
4. The optical lens assembly according to claim 1 , wherein the lens with the first overall shape has a Sag of at least 15 μm.
5. The optical lens assembly according to claim 1 , wherein a central section of the pre-shaped membrane has a substantially spherical shape and a circumference of this central section defines an aperture of the lens assembly.
6. The optical lens assembly according to claim 1 , wherein the Sag of at least 10 μm for the first overall shape corresponds to a first optical power of at least 5 diopters.
7. The optical lens assembly according to claim 1 , where the different optical property is Sag and/or optical power and/or optical aberration.
8. The optical lens assembly according to claim 5 , wherein the different optical property includes optical power, wherein the lens has a second optical power with the second overall shape and, wherein a difference between the first and the second optical power, an optical power range, is at least 2 diopters.
9. The optical lens assembly according to claim 1 , wherein the lens body has an upper surface part shaped to correspond to the shape of the pre-shaped membrane.
10. The optical lens assembly according to claim 1 , wherein the lens with the first overall shape has a Sag of at least 20 μm.