High speed piezoelectric optical system with tunable focal length

An optical system with tunable focal length, the optical system comprising:

• A. a substrate;
• B. a deformable optical element deposited on said substrate, said optical element being characterized by a built-in curvature and a focal length;
• C. a thin film deposited on at least a portion of said deformable optical element, said thin film comprising piezoelectric material and having a first electrode disposed on one end thereof and a second electrode disposed on another end thereof;
• wherein upon application of an electric voltage between said first electrode and said second electrode, a lateral strain is induced in said thin film, thereby modifying said nominal curvature and said focal length of said optical element.

An optical switch, comprising:

• A. an input fiber for transmitting incoming optical radiation therethrough;
• B. a first output fiber and a second output fiber;
• C. a varifocal optical lens having a tunable focal length, the tunable range of said optical lens including at least a first focal length and a second focal length;
• and
• D. means for directing said incoming optical radiation onto said first output fiber when said optical lens is tuned to said first focal length, and for directing said incoming optical radiation onto said second fiber when said optical lens is tuned to said second focal length;
• wherein said varifocal optical lens includes a deformable membrane having a nominal curvature, and a PZT thin film deposited thereon;
• and
• wherein application of an electric voltage between a first and a second electrode disposed on said thin film induces a strain on said thin film, thereby modifying the focal length of said optical lens.

A varifocal lens, comprising:

• A. a volume of refractive liquid, said liquid being characterized by a focal length;
• B. at least one membrane forming a boundary of said volume of refractive liquid, said membrane being characterized by a curvature;
• C. a PZT thin film deposited on said membrane, said PZT film including a first and second electrode;
• wherein application of an electric voltage between said first electrode and said second electrode alters the dimensions of said film, thereby modifying the curvature of said membrane so as to modify said focal length of said refractive liquid.

A varifocal lens, comprising:

• A. a volume of refractive liquid, said liquid being characterized by a focal length;
• B. a first membrane and a second membrane forming the upper and lower boundaries, respectively, of said volume of refractive liquid, each membrane being characterized by a curvature;
• C. a first and a second PZT thin film deposited on a respective one of said first and second membranes, each PZT film including first and second electrodes;
• wherein application of an electric voltage between said first electrode and said second electrode of each PZT thin film alters the dimensions of each film, thereby deforming each respective membrane so as to alter the curvature of each membrane and modify the focal length of said refractive liquid.

A varifocal optical lens for sample height variation compensation in a scanning confocal microscope of the type including a beamsplitter, an objective lens for focusing light transmitted by said beamsplitter onto a spot in its focal plane, and a pinhole aperture disposed adjacent to a detector for preventing light from out-of-focus portions of said sample from reaching said detector, said varifocal optical lens comprising:

• A. a substantially circular membrane deposited on a substrate and having a focal length;
• B. a ring-shaped PZT thin film deposited on an outer portion of said membrane and extending between a first electrode and a second electrode;
• wherein application of an electric voltage between said first electrode and said second electrode alters the dimensions of said thin film so as to deform said membrane, thereby altering the focal length of said optical lens;
• and
• wherein said varifocal optical lens is disposed between said dichroic beamsplitter and said pinhole aperture so as to focus light originating from said sample and transmitted through said beamsplitter onto said aperture, said varifocal optical lens being operable to tune its focal length in order to <compensate for sample height variation.

A method for tuning the focal length of an optical element, said method comprising:

• A. etching a substrate to fabricate a membrane in a buckled state, said membrane being characterized by a nominal curvature and a focal length;
• B. depositing a PZT thin film upon at least a portion of said membrane layer;
• C. providing a first electrode at an outer end of said thin film, and a second electrode at an inner end thereof;
• and
• D. applying an electric voltage between said first electrode and said second electrode, thereby inducing a lateral strain in said PZT thin film;
• wherein said lateral strain alters said nominal curvature and said focal length of membrane.