Abstract: A speed detection apparatus includes a storage unit configured to store time when each of first and second sensors detects an arbitrary detection mark and an address corresponding to the detection mark. The speed detection apparatus further includes a same mark detection time identification unit configured to identify, based on output information from a reference speed detection unit, time when the first and second sensors detect the same mark, based on the address and the time stored in the storage unit, and a relative speed calculation unit configured to calculate, based on output information from the same mark detection time identification unit, a speed of the first sensor and the second sensor relative to a scale member.

Abstract: A Bi-substituted rare earth iron garnet single crystal has a composition of R3-xBixFe5-wAwO12 (wherein R denotes one or more rare earth elements among Tb, Y, Eu, Gd, Ho, Yb, Lu, Nd, Tm, La, Sm, Dy, Er, Ce, and Pr and inevitably include Tb; A denotes one or more elements among Ga, Al, In, Sc, Co, Ni, Cr, V, Ti, Si, Ge, Mg, Zn, Nb, Ta, Sn, Zr, Hf, Pt, Rh, Te, Os, Ce, and Lu, 0.7<x?1.5, and 0<w?1.5), contains Pt and does not contain Pb, and additionally contains Mn or at least one Group 2 element, wherein the coefficient ? is set at a value within a numerical range of 0.91±0.05 and ? (which means [M]?(?×[Pt])) is set from ?7.23 atppm to 1.64 atppm.

Abstract: The reflection detection apparatus includes multiple light-receiving elements configured to detect a pattern formed on an object by receiving a reflected light from the object, and a selector configured to select a first light-receiving element group from the multiple light-receiving elements. The selector is configured to select the first light-receiving element group that includes one or more light-receiving elements each mainly receiving a specularly reflected light from an area of the object where no pattern is formed among the multiple light-receiving elements, on a basis of outputs from the multiple light-receiving elements. The detection of the pattern is made on a basis of an output from the first light-receiving element group.

Abstract: A scale is configured to measure a displacement or velocity of a rotating object. The scale includes a first region that includes a first mark row including a plurality of marks arranged in a first period, and a second region that includes a second mark row including a plurality of marks arranged in a second period having a phase continuity with the first mark row formed in the first region. A periodic mark row including the first mark row and the second mark row is formed over an entire circumference of the rotating object including the first region and the second region.

Abstract: A displacement measuring apparatus includes a light source configured to illuminate light, and a photodetector provided on a structure and configured to detect reflected light from a reflection portion of a scale that alternately and periodically includes a convex portion scattering the light from the light source and the reflection portion reflecting the light, the displacement measuring apparatus measures a relative displacement between the structure and the photodetector based on a detection result from the photodetector, a length of the reflection portion in a period direction of the scale is greater than a half of a sum of lengths of the convex portion and the reflection portion, and the reflection portion includes a curved concave portion that reflects and collects the light illuminated from the light source.

Abstract: A displacement measuring apparatus 100 which measures a displacement amount of a moving object 102 includes a light source that irradiates the moving object 102 using luminous flux emitted from a light emitting area 101, a photo diode array 104, 105 that includes a plurality of light receiving areas in a movement direction of the moving object 102 and that forms an image of the luminous flux reflected on a plurality of indentations 103 of the moving object 102 to receive light, and a measurement unit that measures the displacement amount of the moving object 102 based on a movement amount of a light emitting area image 106 that is formed on the photo diode array 104, 105 by forming the image of the luminous flux.

Abstract: A speed detection apparatus includes a storage unit configured to store time when each of first and second sensors detects an arbitrary detection mark and an address corresponding to the detection mark. The speed detection apparatus further includes a same mark detection time identification unit configured to identify, based on output information from a reference speed detection unit, time when the first and second sensors detect the same mark, based on the address and the time stored in the storage unit, and a relative speed calculation unit configured to calculate, based on output information from the same mark detection time identification unit, a speed of the first sensor and the second sensor relative to a scale member.

Abstract: A Bi-substituted rare earth iron garnet single crystal has a composition of R3-xBixFe5-wAwO12 (wherein R denotes one or more rare earth elements among Tb, Y, Eu, Gd, Ho, Yb, Lu, Nd, Tm, La, Sm, Dy, Er, Ce, and Pr and inevitably include Tb; A denotes one or more elements among Ga, Al, In, Sc, Co, Ni, Cr, V, Ti, Si, Ge, Mg, Zn, Nb, Ta, Sn, Zr, Hf, Pt, Rh, Te, Os, Ce, and Lu, 0.7<x?1.5, and 0<w?1.5), contains Pt and does not contain Pb, and additionally contains Mn or at least one Group 2 element, wherein the coefficient ? is set at a value within a numerical range of 0.91±0.05 and ? (which means [M]?(?×[Pt])) is set from ?7.23 atppm to 1.64 atppm.

Abstract: A displacement measuring apparatus includes a light source configured to illuminate light, and a photodetector provided on a structure and configured to detect reflected light from a reflection portion of a scale that alternately and periodically includes a convex portion scattering the light from the light source and the reflection portion reflecting the light, the displacement measuring apparatus measures a relative displacement between the structure and the photodetector based on a detection result from the photodetector, a length of the reflection portion in a period direction of the scale is greater than a half of a sum of lengths of the convex portion and the reflection portion, and the reflection portion includes a curved concave portion that reflects and collects the light illuminated from the light source.

Abstract: Provided is a Bi-substituted rare earth iron garnet single crystal which has a composition of R3-xBixFe5-wAwO12, wherein R denotes one or more rare earth elements among Y, Eu, Gd, Ho, Yb, Lu, Nd, Tm, La, Sm, Dy, Er, Ce, and Pr while definitely including Gd, A denotes one or more elements among Ga, Al, In, Sc, Co, Ni, Cr, V, Ti, Si, Ge, Mg, Zn, Nb, Ta, Sn, Zr, Hf, Pt, Rh, Te, Os, Ce, and Lu, 0.7<x?1.5, and 0<w?1.5, does not contain Pb and contains Pt, and additionally contains M which denotes Mn or at least one Group 2 element, wherein a coefficient ? is set to any value within a numerical range of 0.815±0.035 and ? (which means (?×[M])?[Pt]) is set from ?0.40 atppm to 3.18 atppm.

Abstract: A displacement measuring apparatus 100 which measures a displacement amount of a moving object 102 includes a light source that irradiates the moving object 102 using luminous flux emitted from a light emitting area 101, a photo diode array 104, 105 that includes a plurality of light receiving areas in a movement direction of the moving object 102 and that forms an image of the luminous flux reflected on a plurality of indentations 103 of the moving object 102 to receive light, and a measurement unit that measures the displacement amount of the moving object 102 based on a movement amount of a light emitting area image 106 that is formed on the photo diode array 104, 105 by forming the image of the luminous flux.

Abstract: Provided is an optical disk apparatus which optimizes a frequency of a high frequency superimposing operation upon reproduction so that good reproduction performance is realized in a wide irradiation power range of a laser power. The optical disk apparatus includes: a semiconductor laser device; an optical disk discrimination circuit for performing laser discrimination; a driver device including a drive circuit for supplying direct drive current to the semiconductor laser device and a high frequency superimposing circuit for superimposing high frequency current on the drive current; and a high frequency superimposing variable circuit for changing a frequency of the high frequency current in which when information is reproduced, the high frequency superimposing variable circuit sets the frequency of the high frequency current for reproducing a multi-layer disk to be higher than the frequency of the high frequency current for reproducing a single-layer disk.

Abstract: Provided is an optical disk apparatus which optimizes a frequency of a high frequency superimposing operation upon reproduction so that good reproduction performance is realized in a wide irradiation power range of a laser power. The optical disk apparatus includes: a semiconductor laser device; an optical disk discrimination circuit for performing laser discrimination; a driver device including a drive circuit for supplying direct drive current to the semiconductor laser device and a high frequency superimposing circuit for superimposing high frequency current on the drive current; and a high frequency superimposing variable circuit for changing a frequency of the high frequency current in which when information is reproduced, the high frequency superimposing variable circuit sets the frequency of the high frequency current for reproducing a multi-layer disk to be higher than the frequency of the high frequency current for reproducing a single-layer disk.

Abstract: The recording medium 12 is radiated with light beam from the second light source to obtain servo signal from the reflected light. At least one of the relay lenses 8 in the relay optical system is moved perpendicularly to the optical axis according to the servo signal to follow-up moving direction of the recording medium. The light beam from the second laser light source merges with an optical system from the first laser light source to the recording medium 12 between at least one of the relay lenses 8 and the spatial light modulator 3.

Abstract: A holographic information recording and reproducing apparatus, comprising a light source; a beam splitter for splitting a beam emitted from the light source into a first beam and a second beam; a spatial light modulator for providing the first beam with information; a first mirror for causing the second beam to be incident on a transmission type information recording medium; a second mirror for causing the second beam that has passed through the information recording medium to be incident on the information recording medium again; a photodetector for detecting the second beam which is caused to be incident on the information recording medium again and exits from the information recording medium toward the first mirror; and a controller for controlling an angle of the second mirror based on a detection result of the photodetector.

Abstract: An optical information recording/reproduction apparatus capable of performing accurate tracking control without depending on a radial runout of an optical disk is provided. Specifically, light reflected on an optical disk is detected by a first photodetector and a tracking error signal is detected from an output thereof. Also, return light reflected on an end surface of an SIL which is opposed to the optical disk is detected by a second photodetector, and a position signal of an optical head portion in a tracking direction is detected from on an output thereof. Further, the tracking error signal is corrected based on the position signal to remove an offset, thereby performing accurate tracking control.