Fingerprint scanner and method having an acoustic detector

1. A fingerprint scanner comprising:

an ultrasonic wave emitter;

a platen capable of supporting a finger and allowing ultrasonic waves to pass through the platen;

an acoustic splitter positioned to reflect ultrasonic waves from the emitter toward the platen, and positioned to allow passage of ultrasonic waves reflected from a finger on the platen;

an acoustic lens positioned between the emitter and the splitter and configured to cause ultrasonic energy passing through the lens from the emitter toward the splitter to diverge and thereby acoustically illuminate a larger surface area; and

an acoustic detector positioned to receive ultrasonic waves that passed through the splitter.

2. The scanner of claim 1 , further comprising a movable carriage supporting the emitter, the splitter and the detector.

3. The scanner of claim 2 , wherein the detector is linearly distributed substantially perpendicular to a direction in which the carriage is movable.

4. The scanner of claim 1 , further comprising an acoustic lens positioned between the splitter and the detector.

5. The scanner of claim 1 , wherein the detector comprises:

a piezoelectric layer capable of producing electric charge at locations which receive an ultrasonic signal;

a charge coupled device in communication with the piezoelectric layer and capable of producing an electric current corresponding the electric charge produced by the piezoelectric layer;

an electric circuit in communication with the charge coupled device and capable of communicating to a receiver the electric currents produced by the charge coupled device.

6. The scanner of claim 1 , wherein the detector is a piezoelectric charge coupled device.

7. The scanner of claim 1 , herein the piezoelectric charge coupled device is linearly distributed.

8. The scanner of claim 1 , further comprising a fluidic ultrasound transmission media between the emitter and the splitter.

9. The scanner of claim 1 , further comprising a fluidic ultrasound transmission media between the splitter and the platen.

10. The scanner of claim 1 , further comprising a fluidic ultrasound transmission media between the splitter and the detector.

11. A method of analyzing a finger, comprising:

providing ultrasonic energy;

directing the ultrasonic energy through an acoustic lens to provide refracted energy, the lens being configured to cause ultrasonic energy passing through the lens towards an acoustic splitter to diverge;

reflecting the refracted energy with the acoustic splitter to provide first reflected energy;

reflecting the first reflected energy from a finger to provide second reflected energy;

receiving the second reflected energy at the acoustic splitter;

allowing the second reflected energy to pass through the acoustic splitter; and

receiving the second reflected energy at an acoustic detector.

12. The method of claim 11 , further comprising moving the splitter and the detector while receiving the second reflected energy.

13. The method of claim 11 , further comprising focusing the second reflected energy on the detector.

14. The method of claim 11 , further comprising focusing the ultrasonic energy on the splitter.

15. The method of claim 11 , wherein receiving the second reflected energy at an acoustic detector includes receiving the second reflected energy on a piezoelectric element, and producing a charge from the element.

16. The method of claim 15 , further comprising detecting the charge and communicating a signal corresponding to the charge.