Confocal Reflector Research Articles

Stacking illumination of a confocal reflector light emitting diode automobile headlamp with an asymmetric triangular prism.

A confocal reflector lamp with an asymmetric triangular prism was designed for a stacking illumination of a light emitting diode (LED) automobile headlamp fitting ECE R112 asymmetrical regulation. The optical system includes three 1st elliptic reflectors, three 2nd parabolic reflectors, and one asymmetric triangular prism. Three elliptic and parabolic reflectors were assembled with three confocal reflector modules; two modules projected the cut-off line of a 0° angle, and the other module projected the cut-off line of a 15° angle using of an asymmetric triangular prism. The ray tracing, optical simulation, and mockup experiment results exhibited that the illumination distribution met the regulation of ECE R112 class B, and the ideal efficiency could reach 96.8% in theory. The tolerance analysis showed the efficiency remained above 98% under the error values of ±0.2 mm of the position of the LED light source, and the y direction of the up-down movement was more sensitive than the x and z directions. The measurement results of the mockup sample safety factor were all larger than 1.15 and supported the regulation of the ECE R112 Class B.

Supersonic-jet cryogenic-resonator coaxially oriented beam-resonator arrangement Fourier transform microwave spectrometer

The design and performance of a cryogenic (T=77K) microwave spectrometer are reported. This instrument, being a time domain experiment in microwave molecular spectroscopy, consists of three basic components: a near-confocal Fabry-Perot-type resonator, a pulsed microwave excitation Fourier transform system, and a pulsed molecular-beam source in a coaxially oriented beam-resonator arrangement. With the recently developed spectrometer, which employs confocal reflectors cooled to liquid-nitrogen temperature, we were able to reduce the system noise of the instrument significantly. The high sensitivity of this next generation spectrometer allows the detection of transient species produced in a dc-discharge nozzle, other short-lived molecules and complexes at low abundance, or nearly nonpolar molecules. We will discuss the spectrometer design with respect to critical considerations of the resonator theory in the context of cryogenic operation, as well as important aspects of classical circuit theory applied to excitation and detection of molecular systems in a resonator. Following the description of the dc-discharge source, the performance of the instrument is demonstrated.

Offset Multireflector Antennas with Perfect Pattern Symmetry and Polarization Discrimination

Conditions are derived that are useful for designing reflector antennas with excellent cross-polarization discrimination. These conditions ensure circular symmetry and absence of cross-polarization everywhere in the far field of an antenna, provided a suitable feed such as a corrugated horn is employed. The spherical wave radiated by the fundamental mode of such a feed has circular symmetry around the axis, and it is everywhere free of cross-polarization. An arbitrary sequence of N confocal reflectors (hyperboloids, ellipsoids, paraboloids) is combined with such a feed. It is shown that it is always possible to ensure circular symmetry (and absence of cross-polarization) in the antenna far field by properly choosing the feed axis orientation. If the final reflector is a paraboloid, a simple geometrical procedure can be used. It is also shown that the asymmetry caused by an arbitrary number of reflections can always be eliminated by properly introducing an additional reflection. An application to the problem of producing a horizontal beam using a vertical feed is discussed. Two arrangements are described that may be useful for radio relay systems.

He-Ne Laser Communication

Preliminary experiments, demonstrating the feasibility of laser communication, using a He-Ne gas laser of cavity length of about 45 cm. with confocal reflector arrangement and of output power of the order of a milliwatt, have been reported. The amplitude modulation is produced by superimposing the audio signal on the exciting d.c. voltage of the discharge tube and the resulting intensity modulated laser beam (λ = 0·6328 μ) is focused on a PMT/solar cell to detect the audio signal. Without using any sophisticated collimating or receiving optics, communication up to a distance of about 100 ft. has been demonstrated and can easily be extended further.