Picosecond laser apparatus and methods for its operation and use
Apparatuses and methods are disclosed for applying laser energy having desired pulse characteristics, including a sufficiently short duration and/or a sufficiently high energy for the photomechanical treatment of skin pigmentations and pigmented lesions, both naturally-occurring (e.g., birthmarks), as well as artificial (e.g., tattoos). The laser energy may be generated with an apparatus having a resonator with the capability of switching between a modelocked pulse operating mode and an amplification operating mode. The operating modes are carried out through the application of a time-dependent bias voltage, having waveforms as described herein, to an electro-optical device (e.g., a Pockels cell) positioned along the optical axis of the resonator.
1. A method for treating a skin pigmentation comprising pigment particles using a photomechanical process, the method comprising exposing at least one pigment particle to pulsed laser energy having a wavelength between 660 nm and 1090 nm and with pulses having a duration that is a multiple of the acoustic transit time across said pigment particle to photomechanically disrupt the pigment particle.
2. The method of claim 1 wherein said pulses have an energy of at least 100 mj.
3. The method of claim 1 wherein said duration is less than 1 nanosecond.
4. The method of claim 1 wherein said duration is at most 500 ps.
5. The method of claim 1 wherein said pulses have a duration of between 100 ps and 300 ps.
6. The method of claim 1 wherein said pulses have a duration of between 100 ps and 500 ps.
7. The method of claim 1 comprising exposing said at least one pigment particle to pulsed laser energy with pulses having a duration below twice the acoustic transit time across said pigment particle.
8. The method of claim 7 wherein said duration is less than 1 nanosecond.
9. The method of claim 7 wherein said pulses have an energy of at least 100 mj.
10. The method of claim 1 comprising exposing said at least one pigment particle to pulsed laser energy with pulses having a duration below five times the acoustic transit time across said pigment particle.
11. The method of claim 10 wherein said duration is less than 1 nanosecond.
12. The method of claim 10 wherein said pulses have an energy of at least 100 mj.
13. The method of claim 1 wherein said pigment particle is in a tattoo.
14. The method of claim 1 wherein said pigment particle is in a birthmark.
15. The method of claim 1 wherein said pigment particle is in a pigmented lesion.
16. The method of claim 1 wherein said pigment particle is in a skin pigmentation.
17. The method of claim 1 wherein the duration is from two times to five times the acoustic transit time across the pigment particle.
18. The method of claim 1 wherein the at least one pigment particle has a diameter of from 1 micron to 10 microns.
19. The method of claim 1 wherein the pigment particle has a diameter from 1 micron to 10 microns.
20. The method of claim 1 wherein the wavelength is between 660 nm and 1060 nm.
21. The method of claim 1 wherein the wavelength is between 980 nm and 1090 nm.
22. The method of claim 1 wherein the wavelength is between 700 nm and 950 nm.
23. The method of claim 1 wherein the wavelength is 694 nm.
24. The method of claim 1 wherein the wavelength is 1064 nm.