Tunable acoustic gradient index of refraction lens and system
A tunable acoustic gradient index of refraction (TAG) lens and system are provided that permit, in one aspect, dynamic selection of the lens output, including dynamic focusing and imaging. The system may include a TAG lens and at least one of a source and a detector of electromagnetic radiation. A controller may be provided in electrical communication with the lens and at least one of the source and detector and may be configured to provide a driving signal to control the index of refraction and to provide a synchronizing signal to time at least one of the source and the detector relative to the driving signal. Thus, the controller is able to specify that the source irradiates the lens (or detector detects the lens output) when a desired refractive index distribution is present within the lens, e.g. when a desired lens output is present.
1. A method for controlling the output of a tunable acoustic gradient index of refraction optical lens, comprising: providing a tunable acoustic gradient index of refraction lens having a refractive index that varies in response to an applied electrical driving signal; irradiating the optical input of the lens with a source of electromagnetic radiation; driving the lens with a driving signal to control the index of refraction within the lens; detecting the electromagnetic radiation output from the driven lens with a detector; and providing a synchronizing signal to the detector to select a time to detect the electromagnetic radiation output from the driven lens when a desired refractive index distribution is present within the lens.
2. The method according to claim 1 , wherein the step of driving the lens comprises driving the lens with a driving signal that causes the optical output of the lens to vary with time to produce an output that comprises a phase mask.
3. The method according to claim 1 , wherein the step of driving the lens comprises driving the lens with a driving signal that creates a substantially parabolic refractive index distribution in the lens, where the refractive index in the lens varies as the square of the radius of the lens.
4. The method according to claim 1 , wherein the driving signal comprises the sum of at least two sinusoidal driving signals of differing frequency and/or phase.
5. The method according to claim 1 , wherein the step of driving the lens comprises driving the lens with a driving signal that creates a plurality of substantially parabolic refractive index distributions within the lens.
6. The method according to claim 1 , wherein the driving signal comprises a waveform other than a single frequency sinusoid.
7. The method according to claim 1 , wherein the step of driving the lens comprises driving the lens with a driving signal that causes the lens to operate to produce an output that comprises a spot at one instance in time and an annular ring at another instance in time.
8. The method according to claim 7 , wherein the step of providing a synchronizing signal comprises timing the detection of electromagnetic radiation to coincide with either the spot or the annular ring output from the lens.
9. The method according to claim 1 , wherein the step of driving the lens comprises driving the lens with a driving signal that causes the focal length of the lens to vary with time to produce a lens with a plurality of focal lengths.
10. The method according to claim 9 , wherein the step of providing a synchronizing signal comprises timing the detection of electromagnetic radiation to coincide with a specific focal length of the lens.
11. The method according to claim 10 , wherein the step of driving the lens comprises driving the lens with a driving signal that causes the lens to operate as at least one of a converging lens and a diverging lens.