Passively Q-switched laser and laser system for ranging applications

A passively Q-switched laser configured to output a series of output pulses in an output beam at an eye-safe lasing wavelength, the passively Q-switched laser comprising:

• a gain element having a first and a second surface, the first surface having a reflective coating at the eye-safe lasing wavelength to form a first end of a resonator;
• a saturable absorber element;
• a space between the gain element and the saturable absorber element;
• a second end of the resonator having a partially transmitting optical coating at the eye-safe lasing wavelength;
• and
• a pump source, wherein the pump source emits a pump beam directed to the first surface of the gain element forming a pump spot, wherein the output pulses are emitted at varying time intervals between successive output pulses so as to form a distinct code and the output pulses have a varying axial mode structure;
• wherein the distinct code cannot be created on demand by electronic means, but is self-created by the passively Q-switched laser.