Picosecond Laser Apparatus and Methods for Treating Target Tissues with Same

A subnanosecond pulse laser apparatus comprising:

• a resonator comprising a first mirror and a second mirror opposing the first mirror, wherein the first mirror and the second mirror are substantially totally reflective;
• a lasing medium;
• an ultrafast switching element;
• and
• a polarizing element along an optical axis of the resonator,
• wherein a first drive circuit is connected to a first end of the ultrafast switching element and a second drive circuit is connected to a second end of the ultrafast switching element, wherein the apparatus
• generates a pulse in response to the first drive circuit applying a periodic voltage waveform to the first end of the ultrafast switching element and
• then amplifies the pulse in response to the first drive circuit applying a first constant voltage to the first end of the ultrafast switching element and maintaining an effective reflectivity of the second mirror at substantially 100%, and
• then extracts the amplified pulse in response to the second drive circuit applying a second constant voltage to the second end of the ultrafast switching element and maintaining an effective reflectivity of the second mirror at substantially 0%.

A laser system comprising:

• a laser source that generates an output beam having a subnanosecond pulse duration;
• and
• an optical system that modifies the output beam to provide a treatment beam having a non-uniform energy profile,
• the non-uniform energy profile being comprised of a plurality of regions of relatively high energy per unit area dispersed within a substantially uniform background region of relatively low energy per unit area;
• wherein the treatment beam is configured such that the regions of relatively high energy per unit area deliver sufficient energy to target tissue illuminated by the regions of relatively high energy per unit area to heat the so-illuminated portions of the target tissue to a first temperature T1 and wherein the substantially uniform background region of relatively low energy per unit area delivers sufficient energy to target tissue illuminated by the regions of relatively high energy per unit area to heat the so illuminated portions of the target tissue to a second temperature T2.

A method of treating tissue comprising one or more regions of scar tissue, the method comprising

• generating, using a laser source, an output beam having a subnanosecond pulse duration;
• modifying the output beam, using an optical system, to provide a treatment beam having a non-uniform profile;
• directing the treatment beam to the one or more regions of scar tissue;
• and
• decreasing visible appearance of the one or more regions of scar tissues in response to the treatment beam.