Apparatus and method of optimizing laser system

A method for producing single-frequency or near-single-frequency operation of a laser beam generated by a laser beam system, comprising:

• providing a laser for emitting a laser beam within a laser beam cavity, the cavity having a length, wherein the length of the cavity may be adjusted to one of a plurality of cavity lengths;
• emitting the laser beam at each one of the plurality of cavity lengths;
• providing a detector for, for each of the plurality of cavity lengths, receiving at least a portion of the laser beam emitted, and generating a signal;
• identifying, via a computer operably coupled to the detector, at least one beat note in the signal for each of at least one of the plurality of cavity lengths, each of the at least one beat note comprising an oscillation in a detected intensity of the signal, the oscillation having a measured amplitude and a measured frequency, the at least one beat note indicating the presence of one or more higher-order transverse modes, longitudinal modes, or both, in the received at least the portion of the laser beam emitted at the at least one of the plurality of cavity lengths;
• selecting, based upon the generated signal for each of the plurality of cavity lengths, at least one of the plurality of cavity lengths for eliminating or minimizing the at least one beat note;
• and
• adjusting the length of the cavity to one of the selected at least one of the plurality of cavity lengths.