Abstract: A light blocking unit includes a plate-like member which is different from a housing member, and a light blocking portion formed on the plate-like member, for blocking light. A light detector has a light receiving portion for receiving light which is partitioned into four divided regions, by a Y-axis-wise parting line and an X-axis-wise parting line in X-Y coordinates, and outputs photoelectric output signals for the respective divided regions in accordance with intensity of the light received by the respective divided regions of the light receiving portion. Of light beams emitted from a polarization beam splitter, a part of the light beams are blocked by the light blocking unit while the other part of the light beams are not blocked and thus emitted to the light detector excluding a region defined by two sides parallel to the parting lines.

Abstract: There is provided an optical head which have no such problems regarding increase in cost and size thereof and can reduce errors by suppressing crosstalk components attributable to reflection on lands of a magneto-optical recording medium and thereby prevent degradation of reproduction characteristics. An optical element includes a light separating section for separating outgoing light and return light, and a phase compensation section for imparting phase compensation to light incident thereon. The optical element is provided on a light path of return light between an objective lens and a photodetector, so as to be closer to the photodetector than the light separating section is. This makes it possible to impart the phase compensation to the return light and prevent the degradation of reproduction characteristics. Light separating elements such as beam splitter are no more necessary in the configuration, with the result that decreases in size and cost can be realized.

Abstract: A light blocking unit includes a plate-like member which is different from a housing member, and a light blocking portion formed on the plate-like member, for blocking light. A light detector has a light receiving portion for receiving light which is partitioned into four divided regions, by a Y-axis-wise parting line and an X-axis-wise parting line in X-Y coordinates, and outputs photoelectric output signals for the respective divided regions in accordance with intensity of the light received by the respective divided regions of the light receiving portion. Of light beams emitted from a polarization beam splitter, a part of the light beams are blocked by the light blocking unit while the other part of the light beams are not blocked and thus emitted to the light detector excluding a region defined by two sides parallel to the parting lines.

Abstract: An optical pickup apparatus in which a plurality of light sources emitting a plurality of light beams whose wavelengths are different from each other and degree of reliability of signals detected by a photodetector is high, a method of controlling the same, and an information recording and reproducing apparatus are provided. An objective lens, a ?/4 plate and a polarizing element whose outer edge portion is formed of a polarizer are formed integrally, which polarizing element is disposed so as to serve as an aperture stop with respect to a return light beam having a shorter wavelength.

Abstract: There is provided an optical head which have no such problems regarding increase in cost and size thereof and can reduce errors by suppressing crosstalk components attributable to reflection on lands of a magneto-optical recording medium and thereby prevent degradation of reproduction characteristics. An optical element includes a light separating section for separating outgoing light and return light, and a phase compensation section for imparting phase compensation to light incident thereon. The optical element is provided on a light path of return light between an objective lens and a photodetector, so as to be closer to the photodetector than the light separating section is. This makes it possible to impart the phase compensation to the return light and prevent the degradation of reproduction characteristics. Light separating elements such as beam splitter are no more necessary in the configuration, with the result that decreases in size and cost can be realized.

Abstract: An optical head includes a semiconductor laser element, an objective lens, and a liquid crystal element, a voltage applying section and a control section. The liquid crystal element is provided on an optical path of diffuse light between the semiconductor laser element and the objective lens is divided into a plurality of divisions. The voltage applying section applies a voltage to the plurality of divisions of the liquid crystal element to change the refractive index of the divisions. The control section controls the operation of the voltage applying section which applies a voltage to the divisions of the liquid crystal element to adjust the amount of phase compensation imparted to light incident on each of the divisions of the liquid crystal element such that a spot formed by light transmitted by the liquid crystal element undergoes a phase change that is uniform in the spot.

Abstract: The gasification-combined power plant of the present invention has a structure wherein a fuel gas is generated by partially oxidizing a carbon-containing fuel 2 with an oxygen-containing gas 3 in the gasification apparatus 1, the sensible heat of the fuel gas is recovered by the heat exchanger 4, char and dust are removed from the fuel gas by the dust collector 5, trace gas components, such as H.sub.2 S and NH.sub.3, are simultaneously removed from the waste gas by the gas separation apparatus 6 based on dry physical adsorption of these components (for example, by a pressure swing adsorption method), the thus separated and removed gas containing high concentrations of trace gas components, such as H.sub.2 S and NH.sub.3, is denitrated and desulfurized by the gas disposal apparatus 7 and then is discharged from the chimney 13 into the atmosphere.

Abstract: The gasification-combined power plant of the present invention has a structure wherein a fuel gas is generated by partially oxidizing a carbon-containing fuel 2 with an oxygen-containing gas 3 in the gasification apparatus 1, the sensible heat of the fuel gas is recovered by the heat exchanger 4, char and dust are removed from the fuel gas by the dust collector 5, trace gas components, such as H.sub.2 S and NH.sub.3, are simultaneously removed from the waste gas by the gas separation apparatus 6 based on dry physical adsorption of these components (for example, by a pressure swing adsorption method), the thus separated and removed gas containing high concentrations of trace gas components, such as H.sub.2 S and NH.sub.3, is denitrated and desulfurized by the gas disposal apparatus 7 and then is discharged from the chimney 13 into the atmosphere.

Abstract: A gasification-type combined electric power generating plant comprises a gasifying furnace, a heat exchanger, a gas purifying device, a gas turbine, and a gas turbine compressor, an exhaust heat recovering boiler, and a steam turbine. To decrease boosting power, increase the energy of recovered heat, and improve the overall efficiency of the plant, the plant further includes a regenerative heat exchanger for cooling an air-like gas bled from the gas turbine compressor, a cooler for cooling the air-like gas passed through the regenerative heat exchanger, a primary air booster for boosting a part of the air-like gas passed through the cooler to deliver a primary air, a secondary air booster for boosting the remainder of the air-like gas passed through the cooler to deliver a secondary air, and a passage through which the secondary air passed through the secondary air booster is supplied to the regenerative heat exchanger where the secondary air is heated and then to the gasifying furnace.