Abstract: An image reading device includes a motor 3, a reading section 7 that reads an image on a medium 5, a first transporting roller 9 that transports the medium in a transport direction F by driving force of the motor and that is provided upstream of the reading section in the transport direction, a second transporting roller 11 that transports the medium in the transport direction by driving force of the motor and that is provided downstream of the reading section in the transport direction, and a measuring section 17, using an encoder sensor 15, configured to measure the rotational position of an encoder scale 13, wherein the encoder scale 13 is provided on a rotation shaft 19 of the second transporting roller 11.

Abstract: A control unit of an image reading device is configured to execute image correction control after performing a first reading operation of reading a medium while transporting the medium in a first direction, and the image correction control includes a second reading operation of reading the medium while transporting the medium in a second direction opposite to the first direction, and a combination process for combining a first area serving as a part of image data acquired through the first reading operation with a second area serving as a part of image data acquired through the second reading operation to acquire image data of one page.

Abstract: An AlGaInPAs-based semiconductor laser device includes a substrate, an n-type clad layer, an n-type guide layer, an active layer, a p-type guide layer composed of AlGaInP containing Mg as a dopant, a p-type clad layer composed of AlInP containing Mg as a dopant, and a p-type cap layer composed of GaAs. Further, the semiconductor laser device has, between the p-type guide layer and the p-type clad layer, a Mg-atomic concentration peak which suppresses inflow of electrons, moving from the n-type clad layer to the active layer, into the p-type guide layer or the p-type clad layer.

Abstract: An AlGaInPAs-based semiconductor laser device includes a substrate, an n-type clad layer, an n-type guide layer, an active layer, a p-type guide layer composed of AlGaInP containing Mg as a dopant, a p-type clad layer composed of AlInP containing Mg as a dopant, and a p-type cap layer composed of GaAs. Further, the semiconductor laser device has, between the p-type guide layer and the p-type clad layer, a Mg-atomic concentration peak which suppresses inflow of electrons, moving from the n-type clad layer to the active layer, into the p-type guide layer or the p-type clad layer.

Abstract: A light confinement layer constructed of a semiconductor that has a refractive index different from that of p-type second cladding layers is formed to a small film thickness of not greater than 2 ?m (about 0.5 ?m) on the whole surface of ridge portions of two semiconductor lasers. Thus, the light confinement layer on the ridge portions is made roughly flat so as to be easily removable by etching. As a result, the exposure of p-type second cladding layers of the ridge portions due to deep etching is prevented to allow the confinement of light into the p-type cladding layers to be stably effected. A dielectric film is formed on the light confinement layer and reinforces the current constriction function lost by the reduction in the thickness of the light confinement layer.

Abstract: On an n-type GaAs substrate 19 are formed an n-type GaAs buffer layer 20, a non-doped AlxGa1-xAs light guide evaluation layer 21, an n-type AlxGa1-xAs first clad layer 22, an n-type AlxGa1-xAs second clad layer 23, a non-doped AlxGa1-xAs first light guide layer 24, a non-doped AlxGa1-xAs quantum well active layer 25, a non-doped AlxGa1-xAs second light guide layer 26, a p-type AlxGa1-xAs first clad layer 27, a p-type GaAs etching stop layer 28, a p-type AlxGa1-xAs second clad layer 29 and a p-type GaAs cap layer 30. The Al crystal mixing ratio of the light guide evaluation layer 21 is equal to that of the first and second light guide layers 24, 26. The semiconductor laser device allows the control of layer thickness and material composition of the light guide layers to be fulfilled with simplicity and high precision.

Abstract: An AlGaAs-based semiconductor laser 29 is formed on an n-type GaAs substrate 21 and thereafter etching is carried out until reaching an n-type AlGaAs clad layer 23 from the surface. Next, the n-type AlGaAs clad layer 23 is removed by etching with an etchant having selectivity to GaAs. Subsequently, the surface of an n-type GaAs buffer layer 22 is lightly etched. Thus, the n-type GaAs buffer layer 22 of the AlGaAs-based semiconductor laser 29 is left in a slightly abraded state on the n-type GaAs substrate 21, maintaining the flatness of the groundwork layer during growing an AlGaInP-based semiconductor laser 38 at the second time. Therefore, the flatness of the crystals of, in particular, an active layer grown at the second time can be improved, and the poor characteristics of the AlGaInP-based semiconductor laser 38 attributed to the poor flatness of the groundwork can be improved.

Abstract: A manufacturing method for a semiconductor laser in which a ratio of a layer thickness obtained by adding the layer thickness of a p-type GaAs cap layer and the layer thickness of a p-type AlxGa1-xAs (X=0.550) second cladding layer to a layer thickness obtained by adding the layer thickness of a p-type GaAs cap layer and the layer thickness of a p-type AlGaInP second upper cladding layer is identical to a ratio of an etching rate for dry etching of the p-type GaAs cap layer and the p-type AlxGa1-xAs (X=0.550) second cladding layer to an etching rate for dry etching of the p-type GaAs cap layer and the p-type AlGaInP second upper cladding layer.

Abstract: There is provided a semiconductor laser device having on a single substrate a plurality of laser portions each oscillating laser light of a different wavelength, the plurality of laser portions containing different types, respectively, of dopant. There is also provided a method of fabricating a semiconductor laser device, forming on a single substrate a plurality of laser portions each oscillating laser light of a different wavelength, initially forming a laser portion in a crystal growth method and subsequently forming another laser portion in a different crystal growth method.

Abstract: An AlGaAs-based semiconductor laser 29 is formed on an n-type GaAs substrate 21, and thereafter, a non-doped GaAs protective layer 30 is formed. When the n-type substrate 21 is exposed by removing by etching a partial region of the AlGaAs-based semiconductor laser 29, an impurity Zn is prevented from evaporating from a p-type GaAs contact layer 28. The deterioration of the characteristic of contact with a p-type electrode as a consequence of a reduction in the carrier density of the p-type contact layer 28 can be prevented. Furthermore, the impurity evaporated from the p-type contact layer 28 can be prevented from readhering onto the exposed n-type substrate 21. A layer where the n-type GaAs substrate 21 and the readhering impurity are mixed with each other is not formed when an AlGaInP-based semiconductor laser 38 is succeedingly formed, and the reliability in long-term operation can be improved.

Abstract: An n-type AlGaAs cladding layer of a first semiconductor laser 39 to be first formed on an n-type GaAs buffer layer 22 is constructed of a two-layer structure of a second n-type AlxGa1-xAs (x=0.500) cladding layer 23 and a first n-type AlxGa1-xAs (x=0.425) cladding layer 24. With this arrangement, in removing by etching the second n-type cladding layer 23 located on the n-type GaAs buffer layer 22 side with HF, no cloudiness occurs since the Al crystal mixture ratio x of the second n-type cladding layer 23 is 0.500, allowing mirror surface etching to be achieved. Moreover, by virtue of selectivity to GaAs, the etching automatically stops in the n-type GaAs buffer layer 22. Even in the above case, ellipticity can be improved by matching the vertical radiation angle ?? to 36 degrees since the Al crystal mixture ratio x of the first n-type cladding layer 24 located on the AlGaAs multi-quantum well active layer 25 side is 0.425.

Abstract: A light confinement layer constructed of a semiconductor that has a refractive index different from that of p-type second cladding layers is formed to a small film thickness of not greater than 2 &mgr;m (about 0.5 &mgr;m) on the whole surface of ridge portions of two semiconductor lasers. Thus, the light confinement layer on the ridge portions is made roughly flat so as to be easily removable by etching. As a result, the exposure of p-type second cladding layers of the ridge portions due to deep etching is prevented to allow the confinement of light into the p-type cladding layers to be stably effected. A dielectric film is formed on the light confinement layer and reinforces the current constriction function lost by the reduction in the thickness of the light confinement layer.

Abstract: There is provided a semiconductor laser device having on a single substrate a plurality of laser portions each oscillating laser light of a different wavelength, the plurality of laser portions containing different types, respectively, of dopant. There is also provided a method of fabricating a semiconductor laser device, forming on a single substrate a plurality of laser portions each oscillating laser light of a different wavelength, initially forming a laser portion in a crystal growth method and subsequently forming another laser portion in a different crystal growth method.

Abstract: An AlGaAs-based semiconductor laser 29 is formed on an n-type GaAs substrate 21 and thereafter etching is carried out until reaching an n-type AlGaAs clad layer 23 from the surface. Next, the n-type AlGaAs clad layer 23 is removed by etching with an etchant having selectivity to GaAs. Subsequently, the surface of an n-type GaAs buffer layer 22 is lightly etched. Thus, the n-type GaAs buffer layer 22 of the AlGaAs-based semiconductor laser 29 is left in a slightly abraded state on the n-type GaAs substrate 21, maintaining the flatness of the groundwork layer during growing an AlGaInP-based semiconductor laser 38 at the second time. Therefore, the flatness of the crystals of, in particular, an active layer grown at the second time can be improved, and the poor characteristics of the AlGaInP-based semiconductor laser 38 attributed to the poor flatness of the groundwork can be improved.

Abstract: An AlGaAs-based semiconductor laser 29 is formed on an n-type GaAs substrate 21, and thereafter, a non-doped GaAs protective layer 30 is formed. When the n-type substrate 21 is exposed by removing by etching a partial region of the AlGaAs-based semiconductor laser 29, an impurity Zn is prevented from evaporating from a p-type GaAs contact layer 28. The deterioration of the characteristic of contact with a p-type electrode as a consequence of a reduction in the carrier density of the p-type contact layer 28 can be prevented. Furthermore, the impurity evaporated from the p-type contact layer 28 can be prevented from readhering onto the exposed n-type substrate 21. A layer where the n-type GaAs substrate 21 and the readhering impurity are mixed with each other is not formed when an AlGaInP-based semiconductor laser 38 is succeedingly formed, and the reliability in long-term operation can be improved.