Laser system with short pulse characteristics and its methods of use

• US 20060187978A1
• Filed: 02/24/2005
• Published: 08/24/2006
• Est. Priority Date: 02/24/2005
• Status: Active Grant

• Current Assignee: Iridex Corporation
• Original Assignee: Iridex Corporation
• Inventors: Buzawa, David M., Telfair, William, Mohr, Stuart, Avisa, Ronald
• Granted Patent: US 7,771,417 B2
• Time in Patent Office: Days
• US Class Current: 372/25
• CPC Class Codes: A61B 2018/00636 Sensing and controlling the application of energy
• CPC Class Codes: A61F 2009/00844 Feedback systems
• CPC Class Codes: A61F 2009/00863 Retina
• CPC Class Codes: A61F 9/008 using laser
• CPC Class Codes: A61F 9/00821 for coagulation
• CPC Class Codes: H01S 3/094076 Pulsed or modulated pumping H01S3/1024 takes precedence
• CPC Class Codes: H01S 3/0941 of a laser diode
• CPC Class Codes: H01S 3/1022 by controlling the optical pumping
• CPC Class Codes: H01S 3/109 Frequency multiplication, e.g. harmonic generation
• CPC Class Codes: H01S 3/1305 Feedback control systems
• CPC Class Codes: H01S 3/1306 Stabilisation of the amplitude
• CPC Class Codes: H01S 3/1312 by controlling the optical pumping

Abstract

A laser system that includes a diode pump source. A frequency doubled solid state visible laser is pumped by the diode pump source and produces a pulsed laser output with a train of pulses. Resources provide instructions for the creation of the pulsed output, with on and off times that provide for substantial confinement of thermal effects at a target site. This laser system results in tissue specific photoactivation (or TSP) without photocoagulation damage to any of the adjacent tissues and without causing full thickness retinal damage and the associated vision loss.

Claims

1. A laser system, comprising:

a diode pump source; and

a frequency doubled solid state visible laser pumped by the diode pump source, the frequency double solid state visible laser producing an pulsed laser output; and

resources that provide instructions for the creation of the pulsed output that has a train of pulses with on and off times that provide for substantial confinement of thermal effects at a target site.

2. The system of claim 1, wherein the train of pulses have a thermal relaxation time less than a thermal relaxation time of the target site.

3. The system of claim 1, wherein the train of pulses have a pulse width that is less than 10 milliseconds.

4. The system of claim 1, wherein the train of pulses has pulses greater than 25 microseconds.

5. The system of claim 1, wherein the resources include a feedback control system.

6. The system of claim 5, wherein the feedback control monitors the laser light delivered to the target site.

7. The system of claim 6, wherein the pulsed output is modified in response to the monitoring.

8. The system of claim 5, wherein the feedback control system includes a controller that produces a control signal.

9. The system of claim 8, wherein the control signal is used to adjust the pulsed output.

10. The system of claim 1, wherein the train of pulses are optimized to confine the thermal effects of a target tissue in a medical treatment.

11. The system of claim 1, wherein the train of pulses are optimized to confine the thermal effect to the RPE without affecting the neurosensory retina of an eye.

12. The system of claim 1, wherein an off time of the train of pulses is of sufficient duration to provide that the target site has sufficient time to cool down from the delivery of a previous pulse before a next pulse is delivered to the target site.

13. The system of claim 1, wherein the resources provide the correct parameters and a trigger to the diode pump source to provide for the pulsed output having the train of pulses with on times that are optimized for confinement of thermal effects.

14. The system of claim 1, wherein the instructions include the following steps:

set a starting current for the diode, set a target power from the laser, and trigger the diode to start.

15. The system of claim 1, wherein the pulsed output has a wavelength in the visible range suitable for a diode pumped solid state laser.

16. The system of claim 1, wherein the pulsed output has a pulse on time of 25 microseconds to 10,000 microseconds.

17. The system of claim 1, wherein the pulsed output has a pulse off time of 75 to 100,000 microseconds.

18. The system of claim 1, wherein the resources is configured to provide repetitive pulses at one target site.

19. The system of claim 1, wherein the solid state laser has a gain medium selected from Nd:

YAG, Nd;

YVO4, Nd;

YLF, Ho;

YAG, Er;

YAG, Yb;

YAG, and Yb;

YVO4.

20. A method of treatment, comprising:

providing a diode pumped, frequency doubled solid state laser system with a pulsed output that has a train of pulses with on times optimized for confinement of thermal effects; and

directing a plurality of pulses to a target site, wherein a temperature rise at the target site is non-additive from pulse to pulse.

21. The method of claim 20, wherein the target site is selected from RPE, capullochoris and choroids of the eye.

22. The method of claim 20, wherein the target site has an area of about 50 microns to 3 mm.

23. The method of claim 20, wherein the pulsed output has a wavelength range in the visible.

24. The method of claim 20, wherein the pulsed output has a wavelength range of 520 to 615 nm.

25. The method of claim 20, wherein the pulsed output has a pulse on time of 25 microseconds to 10,000 microseconds.

26. The method of claim 20, wherein the pulsed output has a pulse off time of 750 to 10,000 microseconds.

27. A method of treating biological tissue by laser surgery, comprising:

providing a frequency doubled solid state visible laser system with a frequency doubler;

providing instructions to the laser system to create a pulsed output that has a train of pulses with on and off times that substantially confine thermal effects;

producing the pulsed output; and

directing the pulsed output to a target site.

28. The method of claim 27, wherein the target site is selected from RPE, capullochoris and choroids of the eye.

29. The method of claim 27, wherein a temperature rise at the target site is non-additive from pulse to pulse.

30. The method of claim 27, further comprising:

utilizing the pulsed output to provide a non-ablative effect at the target site.

31. The method of claim 27, wherein the pulsed output is delivered to the target site until an integral of time and energy reaches an endpoint.

32. The method of claim 27, wherein the train of pulses have a pulse width that is less than 10 milliseconds.

33. The method of claim 27, wherein the train of pulses has pulses greater than 25 microseconds.

34. The method of claim 27, wherein the target site is selected from RPE, capullochoris and choroids of the eye.

35. A laser treatment system, comprising:

a diode pump source coupled to a frequency doubled solid state visible laser pumped by the diode pump source, the frequency double solid state visible laser producing an pulsed output; and

a controller system responsive to a photodetector that provides instructions to the visible laser to create a pulsed output that has a train of pulses with on and off times that substantially confine thermal effects.

36. The system of claim 35, wherein the controller includes a processor that compares the photodetector signal to the target power and uses this comparison to determine the on and off times.

37. The system of claim 35, wherein the controller includes a high speed circuit that compares the photodetector signal to the target power and uses this comparison to determine the on and off time of each pulse.

38. The system of claim 35, wherein the controller includes a high speed circuit and a processor that compares the photodetector signal to the target power and uses this comparison to determine the on and off times.