By the use of a highly efficient optical system developed by calculation and experiment on a light source for pumping and its light collecting system, a new tandem type ruby laser unit has been devised.
For measuring the laser output, use of a photomultiplier with an interference filter is proposed whereby the peak value in a wide range of wattage and total output energy become measurable.
In normal operation with one head, the measured threshold input energy for laser oscillation is only 75 joules that makes a new record.
From far-field and interference patterns, the coherence of the laser output is determined.
In a light amplification experiment, in which one head with resonator is used as oscillator and the other head without resonator is used as amplifier, gain of 3.8 dB is obtained.