ABSTRACT
Highly sensitive polarization-controlled optical switching is demonstrated experimentally through a photorefractive BaTiO(3) double-phase-conjugate mirror. A theoretical explanation is developed, and possible applications are mentioned.
ABSTRACT
The laboratory performance of recently proposed new architectures for optical communication through distorting media is investigated. After phase-conjugating a weak beam with a mutually incoherent source a power amplification with a gain factor of 500 was demonstrated. The amplified beam can be employed for distortion-free optical communication by direct signal transmission. In a different configuration, wavefront matching applicable for coherent detection is proved to be feasible.
ABSTRACT
The basic principle and experimental results of applying a specific contact screen for performing multiplex holographic filtering in a real-time coherent optical correlator are presented. The specific design and fabrication of a 1- and 2-D gray density contact screen as well as a 2-D dichromated gelatin phase screen are described. The 2-D density-type screen can yield nearly an equal intensity 5 x 5 array of spectrum islands at the Fourier plane of a Fourier transform lens in a coherent optical image processor. The main drawback of the density-type screen is the lack of required light efficiency at the Fourier plane because of the blocking of light by the silver particles in the screen. Dichromated gelatin phase screens can be made to alleviate this problem, but it is very difficult to fabricate a phase screen exactly according to our design due to inherent experimental limitations. Nevertheless a functional phase screen has been made for the desired correlation functions. Experimental results have demonstrated that the phase screen is reasonably efficient for the multiplex holographic filtering in the real-time correlator.
ABSTRACT
A lamellar grating has been developed to be used for very far ir observations on the Gerard P. Kuiper Airborne Observatory. The design characteristics and performance during laboratory testing and initial observations of Jupiter at wavelengths between 50 microm and 500 microm are presented.
ABSTRACT
The existing observational data for the binary pulsar PSR 1913 + 16 are sufficient to give a rather well-defined model for the system. On the basis of evolutionary considerations, the pulsar must be a neutron star near the upper mass limit of 1.2 solar masses (M.). The orbital inclination is probably high, i>/= 700, and the mass of the unseen companion probably lies close to the upper limit of the range 0.25 M. to 1.0 M.. The secondary cannot be a main sequence star and is probably a degenerate helium dwarf. At the 5.6-kiloparsec distance indicated by the dispersion measure, the magnetic dipole model gives an age of approximately 4 x 104 years, a rate of change of the pulsar period of P approximately 2 nanoseconds per day, and a surface magnetic field strength approximately (1/3) that of the Crab pulsar. The pulsar is fainter than an apparent magnitude V approximately + 26.5 and is at least approximately 80 times fainter than the Crab pulsar in the x-ray band. The companion star should be fainter than V approximately + 30, and a radio supernova remnant may be detectable near the position of the pulsar at a flux level of
ABSTRACT
The period of optical pulsations from NP 0532 has been determined to within 3 nanoseconds on three different nights. The time rate of change of the period (dP/dt)(p) was 36.17 x 10(-9) second per day. The pulse shape was highly asymmetrical with strong indications of structure. The ratio of the amplitude of the main pulse to that of the interpulse varied with time. No evidence was found for photon coincidences in the pulse on a time scale shorter than 2 microseconds.
ABSTRACT
The pulsating radio star reported by Hewish et al. (1) has been studied in the blue region of the optical spectrum and found to have a pulse amplitude less than 10 percent of the photon count expected for 18th magnitude. No upper limit to a sinusoidal oscillation less than or equal to a complete modulation can be set.
