Dermatological systems and methods with handpiece for coaxial pulse delivery and temperature sensing

A method for treating the skin of a patient with therapeutic laser pulses, the method comprising:

• a) using a handpiece adapted to receive therapeutic laser pulses from a laser source and direct each therapeutic laser pulse to one of a plurality of target skin areas along a first optical path, wherein at least a portion of the first optical path is different for each target skin area to which a therapeutic laser pulse is applied, the handpiece comprising:
• 1) a first end for receiving the therapeutic laser pulses from the laser source;
• 2) a first mirror having an open area comprising one of an aperture and a slot, wherein the open area is located in the first optical path for each target skin area of the plurality of target skin areas;
• 3) at least one second optical element comprising a second mirror that is movable to a plurality of different second mirror positions, wherein the second mirror is located in the first optical path for each target skin area of the plurality of target skin areas;
• 4) a contact cooling unit at a second end of the handpiece, comprising a cooling window for contacting and cooling a first skin area, wherein the cooling window is located in the first optical path for each target skin area of the plurality of target skin areas and is transmissible to the laser pulses and to infrared energy, wherein each target skin area of the plurality of target skin areas comprises a different portion of the first skin area cooled by the contact cooling window;
• and
• 5) a temperature sensing element adapted to sense, at each of the plurality of different second mirror positions, infrared energy radiated through the cooling window from substantially only a selected one of the plurality of target skin areas along a second optical path that is generally counterdirectional to, and shares a common optical axis with, the first optical path for the selected one of the plurality of target skin areas, wherein
• A) at least a portion of the second optical path for each target skin area of the plurality of target skin areas is different from every other second optical path;
• B) the first and second mirror are located in the second optical path for each target skin area of the plurality of target skin areas;
• C) the second mirror is positioned within the handpiece to, at each of the plurality of different second mirror positions, direct one or more laser pulses to the selected one of the plurality of target second areas along the first optical path, receive infrared energy radiated along the second optical path from substantially only the selected one of the plurality of target skin areas through the cooling window, and direct at least a portion of the received infrared energy to the reflective portion of the first optical element;
• D) the first mirror is positioned within the handpiece to receive the at least a portion of the infrared energy from the second mirror and to reflect the infrared energy received from the second mirror to the temperature sensing element;
• and
• E) the temperature sensing element is adapted to generate a first signal indicative of the infrared energy received from the first optical element;
• b) contacting the first skin area with the cooling window;
• c) cooling the first skin area using the cooling window;
• d) receiving at least one therapeutic laser pulse from a laser source at the first end of the handpiece;
• e) applying the at least one therapeutic laser pulse to a selected one of the plurality of target skin areas within the first skin area by directing the laser pulse along the first optical path of the selected one of the plurality of target skin areas, the therapeutic laser pulse passing through the open area of the first mirror, engaging the second mirror, and passing through the cooling window to the selected one of the plurality of target skin areas;
• f) sensing infrared energy radiated from the selected one of the plurality of target skin areas along the second optical path of the selected one of the plurality of target skin areas, the second optical path passing from the selected one of the plurality of target skin areas through the cooling window, engaging the second mirror, and being reflected by the first mirror onto the temperature sensing element;
• and
• g) determining the surface temperature of the selected one of the plurality of target skin areas one or more times before, during or after the application of the at least one therapeutic laser pulse to the target skin area using the temperature determination unit.