Abstract: A method of suppressing noise and improving the optical transmission characteristic of a wavelength division multiplexing transmission system provides lights for suppressing noise from the light sources (NS1 and NS2) which are multiplexed on the wavelength division multiplexed signal. Consequently, the S/N ratio of each channel of a wavelength division multiplexed signal which propagates through the optical path can be improved.

Abstract: A light amplifying apparatus adopting a redundant structure. Optical isolators 13, 14 are inserted between pump light sources 1, 2 and a photocoupler 4 so as to prevent injection locking, thereby preventing fluctuation of pump power.In another embodiment, optical fibers 15 adequately longer than the coherence length of the excitation light waves output from the pump light sources are provided. In still another embodiment, the frequency of the driving current for the pump light sources is modulated. In a further embodiment, wave plates 20, 21 are provided so as to circularly polarize the light waves output from the pump light sources clockwise and counterclockwise.

Abstract: A method for ready and thorough erasure of information in a scan converter storage tube of the class including an electron gun of an electrostatic focus and deflection variety and a storage target having a substrate made from sapphire or like monocrystalline insulator. The storage surface of the substrate is first primed by a scanning electron beam from the electron gun while the potential of a collector electrode on the storage surface is set higher than the value which is lower than the potential of the field mesh electrode of the electron gun by up to about 100 volts. Then the storage surface is again scanned after setting the collector electrode potential higher than the potential of the cathode included in the electron gun and at such a value that the storage surface potential with respect to the cathode potential becomes less than a potential at which the secondary emission ratio of the monocrystalline substrate first becomes unity.

Abstract: An optical lens system is provided having the capability of selectively varying the peripheral field curvature to improve focusing for nonplanar objects and for special photographic effects. The lens system can include in sequence, a first lens group of positive refractive power, a second lens group of negative refractive power and a third lens group of positive refractive power. The specific refractive power of the first and second lens group are designed so that the optical ray traces from an object on the optical axis at infinity will run approximately parallel with the optical axis in the space between the second and third lens groups. The first and second lens groups being movable as a unit relative to the third lens group to change the field curvature without varying the back focal distance of the lens system.

Abstract: The present lens system is capable of providing both a zooming operation and also a relatively efficient and economical macrophotography mode of operation. The zoom lens system contains the basic conventional lens groups of a focusing lens group, variator lens group, compensator lens group and relay lens group. These individual lens group function in a conventional manner during a zooming mode of operation. However, during the macrophotography mode of operation, the individual lens element that form the relay lens group are capable of coordinate movement with other lens elements in the lens system to provide a relatively compact and economical lens design for macrophotography.

Abstract: A varifocal lens assembly of a type including at least two lens groups, a first lens group being axially movable parallel to the optical axis of the varifocal lens assembly for varying the focal length of the optical system of the varifocal lens assembly. An automatic focusing device is associated with the varifocal lens assembly to axially move the lens groups as a whole, the other or second lens group or a part of lens elements of the other or second lens group a predetermined distance to compensate for the image shift which takes place during the adjustment of the focal length effected by axially moving the first lens group.

Abstract: An optical system in a single or double tube color television camera for minimizing color shading, moire patterns and color beats includes along the image optical axis a phase grating low pass filter, a color encoding filter and a lenticular lens member oriented relative to each other and the image scanning to minimize interference between the color encoding filter and striped patterns in the viewed object. The color encoding filter is striped, the low pass filter is either striped or has regularly longitudinally and transversely spaced phase retarding projections and the lenticular lens member includes transversely spaced longitudinal cylindrical lenses or regularly transversely and longitudinally spaced convex projections.