System and method for tissue treatment

1. A system comprising:

an optical element configured to receive an electromagnetic radiation (EMR), and focus the EMR along an optical axis to a focal region in a target tissue;

a controller configured to direct the focal region along a treatment path in the target tissue;

a cooling element down-beam from the optical element and configured to be removably attached to the system via three or more datums and to receive the focusing EMR, the cooling element comprising:

a first window comprising a first proximal surface and a first distal surface;

a second window down-beam from the first window, the second window comprising a second proximal surface and a second distal surface, wherein the second window is configured to contact the target tissue or a tissue adjacent to the target tissue via the second distal surface, and wherein the treatment path is parallel to the second distal surface within 50 milliradians;

a coolant chamber located between the first distal surface of the first window and the second proximal surface of the second window and configured to receive a coolant.

2. The system of claim 1 , wherein the controller is configured to vary a first distance between the focal region and the second distal surface of the second window along the optical axis by varying a second distance between the optical element and the second distal surface of the second window along the optical axis.

3. The system of claim 2 , wherein the first distance varies between a first predetermined value and a second predetermined value as the focal region traverses along the treatment path in the target tissue.

4. The system of claim 3 , wherein a difference between the first predetermined value and the second predetermined value is less than 0.25 mm.

5. The system of claim 3 , wherein the first predetermined value is 0.001 mm and the second predetermined value is 10 mm.

6. The system of claim 1 , wherein the controller is configured to vary a first distance between the focal region and the second distal surface of the second window along the optical axis by varying a divergence associated with the EMR.

7. The system of claim 1 , further comprising a scanner, wherein the scanner is configured to receive a control signal from the controller and move the focal region along the treatment path based on the control signal.

8. The system of claim 1 , wherein the controller is configured to vary an intensity of the EMR.

9. The system of claim 1 , wherein the controller is configured to vary a flow rate of the coolant in the coolant chamber.

10. The system of claim 1 , wherein the optical element has a numerical aperture (NA) in the range of about 0.1 to about 1.0.

11. The system of claim 1 , wherein the EMR has an average power in the range of about 1 W to about 100 W.

12. The system of claim 1 , wherein the EMR includes a pulsed laser beam having a wavelength in a range of about 400 nm to about 4000 nm.

13. The system of claim 1 , wherein the EMR is configured to generate thermionic plasma in the focal region.

14. The system of claim 1 , further comprising a gas source configured to direct a gas at the first window, the gas configured to prevent condensation on the first window.

15. The system of claim 1 , wherein the first window has a first thermal effusivity and the second window has a second thermal effusivity that is greater than the first thermal effusivity.

16. The system of claim 1 , wherein the first window and the second window are sealed to a frame of the cooling element via a first seal and a second seal, respectively, wherein the first and the second seals include one or more of a weld, a braze and a solder.

17. The system of claim 1 , wherein the optical element is configured to change a location of the focal region along the optical axis by traveling along the optical axis.

18. A method comprising:

generating, by an optical element, a focusing electromagnetic radiation (EMR) configured to focus to a focal region in a target tissue;

transmitting the focusing EMR through a cooling element configured to be removably attached to the system via three or more datums, wherein the cooling element includes:

a first window comprising a first proximal surface and a first distal surface,

a second window down-beam from the first window, the second window comprising a second proximal surface and a second distal surface, wherein the second window is configured to contact a target tissue or a tissue adjacent to the target tissue via the second distal surface, and

a coolant chamber located between the first distal surface of the first window and the second proximal surface of the second window and configured to receive a coolant; and

directing the focal region along a treatment path in the target tissue, wherein the treatment path is parallel to the second distal surface within 50 milliradians.

19. The method of claim 18 , wherein generating the focusing EMR comprises placing the optical element along an optical axis of the EMR.

20. The method of claim 19 , further comprising varying a depth of the focal region in the target tissue by varying a location of the optical element along the optical axis.

21. The method of claim 20 , wherein the depth of the focal region ranges from about 0.001 mm to about 10 mm.

22. The method of claim 18 , further comprising scanning the focusing EMR along the treatment path in the target tissue.

23. The method of claim 18 , wherein the first window has a first thermal effusivity and the second window has a second thermal effusivity that is greater than the first thermal effusivity.

24. The method of claim 18 , further comprising directing a non-condensing gas at the first proximal surface.