Showing papers on "Ring laser published in 1970"

Lock‐In and Intensity‐Phase Interaction in the Ring Laser

Abstract: The lock‐in threshold of a single‐mode 0.633‐μ He–Ne laser was measured. Experiments were performed with a 1:1 mixture of the 20Ne and 22Ne isotope. The lock‐in threshold was found to increase with operation of the laser with smaller excess unsaturated gain. Minimum lock‐in threshold was found to occur at a higher frequency than the frequency at which the output power was a maximum. A rotational mode competition between the oppositely directed traveling waves was found for rotation rates less than the lock‐in threshold. The beam traveling with and against the direction of rotation was found to decrease and increase, respectively, with increasing rotation rate. Analysis showed that the single‐mode‐ring, laser equations, with mode coupling due to backscattering, satisfactorily explained the experiments.

Loss Lock‐In in the Ring Laser

Abstract: In the ring laser, frequency synchronization between the oppositely directed traveling waves is usually attributed to mutual coupling by the mechanism of the backscattering of energy from each of the beams into the direction of the other. A new type of coupling is introduced where the standing wave state is shown to have less losses than the traveling wave state for rotations rates less than some critical lock‐in threshold. The coupling mechanism is spacially varying losses over the cavity length. The minimum loss condition is also shown to determine the location of the nodes of the standing waves. In certain cases, lock‐in thresholds due to nonuniform losses are shown to have the potential of being a few orders‐of‐magnitude greater than thresholds attributed to backscattering.

Computer for use with ring laser rotational rate sensors

Abstract: A computer responsive to the pulse sequence output signal of a ring laser rotational rate sensor having contra-rotating beams and biasing means to prevent mode locking. The biasing means selectively changes the effective optical path length around the ring of one of the beams with respect to the other. The pulse repetition frequency of the laser output pulse sequence is representative of the difference in oscillation frequency between the contra-rotating beams. The computer comprises a bias control circuit for selecting the polarity of the bias applied to the ring and includes a compensation circuit for providing a bias compensation pulse sequence whose pulse repetition frequency is representative of the magnitude of the applied bias. The computer in addition provides signals representative of the polarities of the laser output pulse sequence and the bias compensation pulse sequence respectively. The laser polarity is chosen in accordance with the selected polarity of the applied bias. The polarity of the bias compensation pulse sequence is chosen opposite to the selected laser polarity. A pulse sequence combining circuit is included for combining the laser output pulse sequence and the bias compensation pulse sequence thereby providing a combined pulse sequence. The pulse sequence combining circuit furthermore combines the associated polarity signals thereby providing a combined polarity signal. The combined pulse sequence is integrated in accordance with the combined polarity signal for providing a signal representative of the ring about an axis normal thereto.

Acousto optic method and apparatus for mode decoupling a ring laser

Abstract: An acousto-optic method and apparatus is disclosed for mode decoupling a ring laser. A pair of acousto-optic filters is disposed in the optical path of the ring laser for collinearly diffracting the counter rotating light beams on acoustic waves in the acousto-optic filters to shift apart the optical frequencies of the counter rotating light beams in the laser gain medium by a certain frequency related to the frequency of the acoustic waves to prevent mode locking of the optical frequencies of the counter rotating light beams. A rotation rate sensor employing the mode decoupled ring laser is disclosed.

Polarization Properties of a Triangular Ring Laser Having a Discharge Tube with Brewster Angle Windows

Abstract: The polarization properties of ring resonators for the case of a single discharge tube with Brewster angle windows in the optical circuit are investigated. The azimuths of polarization of the traveling waves and the related reflection losses due to the Brewster angle windows are calculated as a function of the orientation angle of the Brewster angle windows for different anisotropic reflectances of the reflecting mirrors of the resonators. The experiments are made on a triangular ring laser which is operated at the 6328 A He–Ne line. The measured polarization and intensity of the output light agree very well with the theoretical predictions.

Apparatus for measuring the linear displacement of a moving object

Abstract: 1285277 Polarizing apparatus V DEMIDENKOV V K PROSVETOV S G SKROTSKY B V RYBOKOV and A M KHROMYKH 20 Nov 1970 55192/70 Heading G2J [Also in Divisions H1 H4 and G1] Linear displacements of an object having a mirror attached thereto, are measured by apparatus including: a laser producing radiation at two slightly differing frequencies, the difference frequency being in the r.f. range; a first photodetector receiving the radiation from the laser to produce a phase reference waveform at the difference frequency; a second photo-detector, receiving radiation from the laser which both has and has not been reflected from the mirror, to produce a waveform whose phase is compared with the reference to indicate the displacement. Ring laser as source. In the arrangement of Fig. 1, a ring laser 1 is used with the aid of Faraday effect device 2, to produce two pairs of beams of the two different frequencies. One pair is mixed by mirror 3 and semi-transparent plate 4 for detection by first detector 9. The beams of the other pair are directed to mirror 5 and to mirror 8 on the object 4 (via semi reflecting plate 6), the reflected beams being combined at semi reflector 7 for detection by the second detector 10. The phase comparison is performed by meter 13 after amplification at 11, 12. Linear laser as source. The axial magnetic field applied to laser 14 produces from either end of the device radiation circularly polarized in clockwise and anti-clockwise directions, the radiation from each end containing both frequencies. At one end, the radiation is passed through a polarizer 17 which converts the beam to linearly polarized radiation and detector 18 develops the reference difference frequency signal. At the other end, radiation passes through quarter wave plate 19 providing radiation linearly polarized in two directions at right angles, these beams being separated by Wollaston prism 20 and subsequently combined at detector 26 by optical mixer elements 21-24 after reflection from mirror 24 fixed to the object. Polarizer 25 ensures that all the radiation reaches the detection polarized in the same direction.

Spontaneous giant pulsing in a ruby laser with one output beam reflected back into the cavity

Abstract: Giant pulses have been observed in a ruby ring laser when one of the output beams is reflected directly back into the laser. The threshold for lasing action does not change when the beam is reflected back, but the output is increased to about 1 J with most of the energy in a few pulses of megawatt power level and 50–100 nsec duration.