Showing papers on "Optical modulator published in 1969"
TL;DR: In this paper, a theoretical analysis of acoustooptical pulse modulators is carried out that yield the intensity and rise time of the scattered light and the optimum relationship between the dimensions of the optical and acoustic beam is given.
Abstract: A theoretical analysis of acoustooptical pulse modulators is given Calculations are carried out that yield the intensity and rise time of the scattered light The optimum relationship between the dimensions of the optical and acoustic beam is given A fast high-efficiency modulator has been built based on the theoretical results The modulator is composed of a 350-MHz ZnO transducer sputtered on a quartz acoustic lens and an As 2 S 3 glass serving as the modulating material With 06 watt of electrical RF peak power driving the modulator, 70 percent of the light intensity (at 063μ) is deflected The rise time of the scattered light pulse is of the order of 6 ns
85 citations
TL;DR: The fused silica stress plate modulator described below offers several advantages over the other known electrooptic modulation devices: primarily, high transmission over a broad wavelength range, and large aperture.
Abstract: The fused silica stress plate modulator described below offers several advantages over the other known electrooptic modulation devices: primarily, high transmission over a broad wavelength range, and large aperture. When operated at its electromechanical resonance frequency of 16.7 kHz, the modulator requires only low voltage, low power drive to operate as a +/-lambda/4 plate. Complete constructional details are given, including a model from which resonance frequencies may be calculated. As part of a circular dichroism apparatus, the modulator has allowed measurement of effects as small as 1 part in 10(5). The possibility of extension of the operating range into the vacuum uv is discussed.
56 citations
TL;DR: The field of magneto-optics is reviewed and the application of a magnetic memory system as a readout technique is discussed in this article and the limitations to packing density are discussed, and it is concluded that packing densities greater than 107bit/in2(including suitable guardbands) are practical.
Abstract: The field of magnetooptics is reviewed and the application of a magnetic memory system as a readout technique is discussed. A review and comparison of the fundamental magneto-optic effects and their utility in a system is presented. It is shown for a longitudinal Kerr readout system that laser and shot noise limit wide-band (1 MHz) signal-to-noise ratios to about 40 dB. Media noise problems are reviewed. The limitations to packing density are discussed, and it is concluded that packing densities greater than 107bit/in2(including suitable guardbands) are practical. The various techniques for optico-thermal recording are surveyed. A discussion of related hardware components (such as optical modulators and lasers) is presented. It is concluded that a viable magnetooptic detection-laser beam memory system is practical. No suitable nonmechanical scanning system has yet been developed.
42 citations
TL;DR: The molecular Stark effect in gases may be used to modify the output of a laser in a systematic fashion, and may therefore be used as the basic constituent in a modulator element to control a laser beam as discussed by the authors.
Abstract: The molecular Stark effect in gases may be used to modify the output of lasers in a systematic fashion, and may therefore be used as the basic constituent in a modulator element to control a laser beam. Experimental data for various CO2 laser lines and a number of electro‐optic gases external to the laser cavity show amplitude modulation up to 20% for about 25% absorption and electric fields of the order of 1 kV/cm.
33 citations
Patent•
29 Dec 1969
TL;DR: In this article, an automatic and autonomous optical guidance system for an autorotative missile to be directed towards a target emitting radiations is presented, where a single flight-control rudder is operated at each revolution of the missile about its axis of rotation.
Abstract: An automatic and autonomous optical guidance system for an autorotative missile to be directed towards a target emitting radiations, the missile having a single flight-control rudder operable at each revolution of the missile about its axis of rotation; comprising an optical target position detecting means for producing, at each revolution of the missile, signals which are a function of the deviation between the autorotational axis of the missile and the missile-target direction; control signal producing means connected to the optical detecting means for generating, at each revolution of the missile, a control energy; and motor means connected to the control signal producing means in order to be supplied thereby and positively coupled with the single flight-control rudder in order to guide the missile, at each revolution thereof, as a function of the deviation between its autorotational axis and the missile-target direction; the optical target position detecting means comprising an optical modulator formed of a plane support provided, radially from a point of origin, with a succession of opaque sectors and transparent sectors arranged in alternate sequence, the optical modulator being disposed in the image plane of an objective lens which projects the target image on to the image plane, and, a photoelectric cell located downstream of the optical modulator for receiving light pulses generated by a relative displacement between the target and the optical modulator, the photoelectric cell converting the light pulses into electric signals which are transmitted to a frequency discriminator producing an output voltage which is a function of the frequency of the pulses, thereby a function of the angular deviation of the target with respect to a reference direction constituted by the optical axis of the optical target position detecting means, the voltage actuating, the control signal producing means; the relative displacement between the optical modulator and the target image being produced by the autorotational movement of the missile.
19 citations
Patent•
10 Jun 1969
TL;DR: An optical frequency shift keying (OFSK) as discussed by the authors is an optical modulator biased to provide optical transmission predominantly at one of the optical frequencies during one binary signal condition and at the other frequency during the second condition.
Abstract: An optical frequency shift keying system for representing a first binary signal condition by a first optical frequency and a second binary signal condition by a second optical frequency by means including an optical modulator biased to provide optical transmission predominantly at one of said optical frequencies during one of said signal conditions and to provide transmission at the other of said optical frequencies during the second condition.
17 citations
TL;DR: A Pockels cell light modulator which operates at radio frequencies is described, which transmits more isotropic radiation and has less phase variation between different components of the radiation than do water cell modulators.
Abstract: A Pockels cell light modulator which operates at radio frequencies is described. It transmits more isotropic radiation than other Pockels cell or water cell modulators that operate at these frequencies. In addition, the modulated light has less phase variation between different components of the radiation than do water cell modulators.
9 citations
Patent•
13 Aug 1969
TL;DR: In this paper, an electro-optical modulator consisting of two narrow linear electrodes on opposite sides of the crystal and parallel to the path of the beam is used to modulate the amount of illumination passing through the optical aperture.
Abstract: An electro-optical modulator comprising an electro-optic crystal, means for projecting a beam of light through the crystal on to an optical aperture, and means for applying to the crystal a variable electric field which will be substantially non-uniform across the beam of light in any plane transverse to the path of the beam so as to cause a variable spreading of the beam and thereby modulate the amount of illumination passing through the optical aperture. The electric field may be applied to the crystal by means of two narrow linear electrodes on opposite sides of the crystal and parallel to the path of the beam. The optical aperture may be a translucent aperture in an opaque screen, or it may be one end of a fiber-optic light guide.
9 citations
Patent•
15 Sep 1969
TL;DR: In this paper, a laser synchronization system synchronizes the emission of a light pulse on a laser triggered by a rotating mirror and the control of the exposure of a photographic camera by means of light pulses.
Abstract: A laser synchronization system synchronizes the emission of a light pulse on a laser triggered by a rotating mirror and the control of the exposure of a photographic camera by means of a light pulse. The system comprises a light detector connected to the camera and is adapted to supply an electrical pulse suitable for controlling the camera. An auxiliary light source in the form of an auxiliary laser directs a light beam through an optical system onto the light detector when the rotating mirror is in appropriate angular position. Two semitransparent mirrors define the optical resonating cavity of the auxiliary laser, and the auxiliary laser emits light in two opposite directions in the form of a visual display beam and a synchronizing beam whereby a visual display of the path of light emitted by the triggered laser is achieved by a continuous light beam supplied by the auxiliary light source.
8 citations
8 citations
Patent•
14 May 1969
TL;DR: In this paper, the LiNbO3 optical modulator in this mode-locked Nd: YAG laser is modulated at a frequency that is different from the laser intermode frequency c/2L by the natural relaxation oscillation frequency associated with the lasing medium.
Abstract: The intracavity LiNbO3 optical modulator in this mode-locked Nd: YAG laser is modulated at a frequency that is different from the laser intermode frequency c/2L by the natural relaxation oscillation frequency associated with the lasing medium.
TL;DR: Light pulses from a mode-locked He-Ne laser have been modulated by a LiTaO(3) electrooptic crystal mounted on a thin film substrate and amplitude modulation of 20% has been achieved at 2 GHz for a single pass through the modulator.
Abstract: Light pulses from a mode-locked He–Ne laser have been modulated by a LiTaO3 electrooptic crystal mounted on a thin film substrate. The crystal was driven by pulses from a GaAs Gunn effect diode. Amplitude modulation of 20% has been achieved at 2 GHz for a single pass through the modulator.
Patent•
13 Nov 1969
TL;DR: In this paper, an electro-optical modulator employing the linear electrooptic effect, also known as the Pockels effect, in P-type crystal material has the optical faces of the crystal body cut at oblique angles to the optic axis.
Abstract: An electro-optical modulator employing the linear electro-optic effect, also known as the Pockels effect, in potassium dihydrogen phosphate or other P-type crystal material has the optical faces of the crystal body cut at oblique angles to the optic axis. Electrodes are arranged so that when a potential difference is applied a component of the resulting field in the body is parallel to the optic axis. In a preferred form the optical faces are so oriented that a beam of light incident on one of the faces at Brewster''s angle passes through the body parallel to the optic axis. Reflections are eliminated when the incident beam is linearly polarized with the electric vector parallel to the plane of incidence, and the electric field in the body is zero.
Patent•
13 Oct 1969
TL;DR: In this paper, a high-speed optical modulator consisting of a fluid oscillator having first and second output channels and means for alternately switching a fluid stream into the first or second output channel is described.
Abstract: A high-speed optical modulator comprised of a fluid oscillator having first and second output channels and means for alternately switching a fluid stream into the first and second output channels. The first output channel serves as part of an optical prism, and air and liquid are alternately present in the first output channel to provide different indices of refraction so that light passing through the optical prism is alternately partially and totally reflected.
01 Jan 1969
TL;DR: The membrane light modulator (MLM) as discussed by the authors is a new solid state device for use in coherent optical computers, which modulates light in reflection using a thin polymer membrane mirror applied over a compartmented sub-structure.
Abstract: An optical spatial phase modulator consisting of a thin polymer membrane mirror applied over a compartmented sub-structure has been devised for use as an input transducer for coherent optical computers. This device is called the ' membrane light modulator' or MLM. Membrane elements are 10 to 50 microns in diameter, have a sub-microsecond response time, and require only 10 picojoules per element to produce a full 360 ° phase reversal in reflection. An array of approximately 2000 elements is described having an active area of 4 by 4 mm. This MLM has been used as an input transducer for a coherent optical computer which takes one-dimensional Fourier transforms. The membrane light modulator (MLM) is a new solid state device for use in coherent optical computers. Many workers have mentioned the enormous parallel data processing capacity of laser illuminated lens systems, where on the order of 101 6 bits per second could be transferred from input to output per watt of illumination. Mankind has not even begun to take advantage of this data processing capability due to an inability to impress sufficiently high frequency signals on the photon flux. The membrane modulator is a first step in the direction of making it possible to achieve a high data processing rate optically by means of parallel processing. This modulator is a spatial light modulator which modulates light in reflection. By ' spatial' it is meant that the optical modulation differs from point to point across the surface of the MLM.
TL;DR: In this paper, an amplitude modulator using a field effect tetrode transistor (FETT) was investigated and the operation of the modulation circuit was based on the ''linear mode'' where the transconductance from one gate to the drain is a linear function of the bias signal at the other gate.
Abstract: An amplitude modulator using a field-effect tetrode transistor (FETT) is investigated. The operation of the modulation circuit is based on the `linear mode' where the transconductance from one gate to the drain is a linear function of the bias signal at the other gate. Experimental result shows that the modulator has good linearity for RF application.
01 May 1969
TL;DR: In this paper, the authors investigated the angular aperture of a simple 2-crystal ADP modulator and found that there is an inherent limitation in the angular apertures.
Abstract: This paper discusses the 45° ycut ADP modulator. An investigation of the propagation of light through the crystal shows that there is an inherent limitation in the angular aperture of the simple 2-crystal modulator. The inclusion of a halfwave plate between the crystals to improve the temperature stability also enables large angular apertures to be achieved, provided the crystals are correctly aligned. Results of measurements carried out on experimental modulators are presented and a comparison made with the 45° zcut modulator.