Optical analyzer assembly and method for intravascular lithotripsy device

A method for treating a treatment site within or adjacent to a vessel wall or a heart valve, the method comprising the steps of:

• generating light energy with a light source;
• positioning a balloon substantially adjacent to the treatment site, the balloon having a balloon wall that defines a balloon interior that receives a balloon fluid that is configured to expand the balloon to an expanded configuration;
• receiving the light energy from the light source with a light guide at a guide proximal end;
• guiding the light energy with the light guide so that the light energy from the light source moves through the light guide in a first direction from the guide proximal end toward a guide distal end that is positioned within the balloon interior, the light energy from the light source that moves through the light guide in the first direction generating plasma in the balloon fluid within the balloon interior that has been used to expand the balloon to the expanded configuration;
• subsequently guiding a portion of the light energy from the light source that generates the plasma in the balloon fluid within the balloon interior that has been used to expand the balloon to the expanded configuration back through the light guide from the guide distal end to the guide proximal end in a second direction that is opposite the first direction, the portion of the light energy that is guided back though the light guide in the second direction being emitted from the plasma that is generated in the balloon fluid within the balloon interior;
• and
• optically analyzing with an optical analyzer assembly the portion of the light energy from the guide proximal end of the light guide that moved back through the light guide in the second direction.