Fractional handpiece with a passively Q-switched laser assembly

1. A fractional handpiece for skin treatment comprising:

a handpiece body comprising:

a passively Q-switched laser assembly within in the handpiece body operatively connected to a pump laser source to receive a pump laser beam having a first wavelength, the passively Q-switched laser assembly comprising one or more pump lenses and a laser cavity comprising one or more external mirrors; and

a beam splitting assembly operable to split a solid beam emitted by the passively Q-switched laser assembly and form an array of micro-beams across a segment of skin, the beam splitting assembly comprising a 1-D beam splitter, a focusing lens, and one or more rollers operable to allow manual movement of the handpiece along a direction perpendicular to a 1-D fractionated micro-dot line to form a 2-D micro-spot pattern,

wherein the passively Q-switched laser assembly generates a high power sub-nanosecond pulsed laser beam having a second wavelength.

2. The fractional handpiece of claim 1 , wherein the laser cavity comprises a high reflector cavity mirror, an output coupler cavity mirror, a gain medium, and a saturable absorber.

3. The fractional handpiece of claim 1 , wherein the laser cavity comprises a high reflector cavity mirror, an output coupler cavity mirror, and a gain medium bonded with a saturable absorber and sandwiched with a high reflective coating at the first wavelength and anti-reflective coating at the second wavelength.

4. The fractional handpiece of claim 3 , wherein the high reflector cavity mirror comprises a coating highly transmissive at the first wavelength and highly reflective at the second wavelength.

5. The fractional handpiece of claim 3 , wherein the output coupler cavity mirror comprises a partially reflective coating at the second wavelength.

6. The fractional handpiece of claim 3 , wherein the gain medium comprises Nd:YAG (neodymium-doped yttrium aluminum garnet), Nd:YAP (Neodymium doped yttrium aluminum perovskite), or Nd:YLF (neodymium-doped yttrium lithium fluoride).

7. The fractional handpiece of claim 3 , wherein the saturable absorber comprises a Cr4+:YAG crystal or ceramic Cr4:YAG.

8. The fractional handpiece of claim 1 , wherein the laser cavity comprises a high reflector cavity mirror, a gain medium, and a saturable absorber, whose output end comprises partially reflective coating at the second wavelength to act as an output coupler.

9. The fractional handpiece of claim 1 , wherein the laser cavity comprises a gain medium with an input end coated with a high transmissive coating at the first wavelength and a high reflective coating at the second wavelength to act as high reflector, a saturable absorber, and an output coupler.

10. The fractional handpiece of claim 1 , wherein the laser cavity comprises a high reflector cavity mirror and a gain medium bonded with a saturable absorber and sandwiched with a high reflective coating at the first wavelength and anti-reflective coating at the second wavelength.

11. The fractional handpiece of claim 10 , wherein the high reflector cavity mirror comprises a coating highly transmissive at the first wavelength and highly reflective at the second wavelength.

12. The fractional handpiece of claim 10 , wherein an input end of the bonded gain medium is coated with anti-reflective coating at both the first wavelength and second wavelength while an output end of the bonded saturable absorber has a partially-reflective coating at the second wavelength to act as an output coupler.

13. The fractional handpiece of claim 1 , wherein the laser cavity comprises an output coupler cavity mirror and a gain medium bonded with a saturable absorber and sandwiched with a high reflective coating at the first wavelength and anti-reflective coating at the second wavelength.

14. The fractional handpiece of claim 13 , wherein the output coupler cavity mirror comprises a partially reflective coating at the second wavelength.

15. The fractional handpiece of claim 13 , wherein an input end of the bonded gain medium is coated with a highly reflective coating at the second wavelength and a highly transmissive coating at the first wavelength to act as a high reflector while an output end of the bonded saturable absorber has an anti-reflective coating at the second wavelength.

16. The fractional handpiece of claim 1 , wherein the beam splitting assembly further comprises a fixed mirror, and a rotational mirror operable to scan a 1-D fractionated micro-dot line to form a 2-D micro-spot pattern.

17. The fractional handpiece of claim 1 , wherein the beam splitting assembly further comprises an axicon diffractive optic to generate donut beam pattern.

18. The fractional handpiece of claim 1 , wherein the handpiece body further comprises a second harmonic generator to generate an additional laser light wavelength.

19. A fractional handpiece for skin treatment comprising:

a handpiece body comprising:

a passively Q-switched laser assembly within in the handpiece body operatively connected to a pump laser source to receive a pump laser beam having a first wavelength, the passively Q-switched laser assembly comprising one or more pump lenses and a laser cavity comprising one or more external mirrors, wherein the passively Q-switched laser assembly generates a high power sub-nanosecond pulsed laser beam having a second wavelength; and

a beam splitting assembly operable to split a solid beam emitted by the passively Q-switched laser assembly and form an array of micro-beams across a segment of skin;

wherein the handpiece body further comprises:

a fast photodetector operable to sense the sub-nanosecond pulsed laser beam and to shut down the pump laser source to avoid double or multiple pulsing;

a homogenizer before the beam splitting assembly to mitigate beam characteristic changes at different repetition rates;

a vibrator operable to vibrate to warn or provide feedback to a user if there is any malfunction of the laser or sliding speed is too slow or too fast;

an attenuator operable to achieve appropriate energy for treatment of different skin types or LIOB depth; and/or

one or two rollers to guide movement of the fractional handpiece and to synchronize with laser pulsing.

20. The fractional handpiece of claim 1 , wherein the one or more rollers are further operable to synchronize with laser pulsing.

21. The fractional handpiece of claim 1 , wherein the handpiece body further comprises a homogenizer before the beam splitting assembly.