The path difference in these two directions causes the two oscillators to operate at different frequencies. When the enclosed ring is rotated in inertial space, the clockwise and counterclockwise paths have different lengths. This last condition actually determines the oscillation frequency of the laser. In addition, the wavelength must be an exact integer for the path around the cavity. If the first condition is to be achieved, the laser frequency must be such that the amplifying medium has sufficient gain to overcome the losses at the reflectors and other elements in the laser path. In order to sustain oscillation, two conditions must be met: The gain must be equal to unity at some power level set by the amplifying medium, and the number of wavelengths in the cavity must be an exact integer (that is, the phase shift around the cavity must be zero). The frequencies at which these oscillators operate are determined by the optical path length of the cavity they travel. In fact, there are two oscillators, one that has energy travelling clockwise, and one that has energy travelling counterclockwise around the same physical cavity. The three mirrors, together with the light-amplifying material in the laser path, comprise an oscillator (laser). The conventional instrument is simply a laser that has three or more reflectors arranged to enclose an area. The laser gyroscope measures path differences of less than 10.sup.-.sup.6 A, and frequency changes of less than 0.1 Hz (a precision of better than one part in 10.sup.15) in order to read rotation rates of less than 0.1.degree. One of the most dramatic recent developments in optical technology is the laser gyroscope, which combines the properties of the optical oscillator, the laser, and general relativity to produce an integrating rate gyroscope. This invention relates to gyroscopes and more particularly to improvements in laser gyroscopes.