Abstract: An optical system includes in order from an object side, an objective optical system, a ?/4 wavelength plate including one birefringent material, a polarizing beam splitter which splits light from the objective optical system into two, and an image sensor which picks up two images split. The polarizing beam splitter causes to occur an axial astigmatism of an opposite sign with respect to an axial astigmatism occurred due to the ?/4 wavelength plate, the following conditional expression (1) is satisfied. 1.1?Fno/(d/|?n|)?49??(1) where, Fno denotes an effective F-number of the objective optical system, d denotes a thickness of the ?/4 wavelength plate, and ?n denotes a birefringence of the ?/4 wavelength plate for an e-line, provided that, |0.01|<?n.

Abstract: There is provided an optical encoder including a photodiode array and a code disk opposite to each other. The photodiode array includes at least three sets of position photodiodes and two index photodiodes arranged transversally. The two index photodiodes are adjacently arranged at the same side of the at least three sets of position photodiodes. A first set of position photodiodes and a last set of position photodiodes of the at least three sets of position photodiodes are partially covered to alleviate the total harmonic distortion. The rest position photodiodes of the at least three sets of position photodiodes other than the first and last sets of position photodiodes are not covered.

Abstract: A light source module includes: laser light sources; parallel light lenses that converts laser beams from the laser light sources to collimated laser beams; a demagnification optical system including that demagnifies the collimated laser beams; an optical fiber; and a condenser lens that converges and couples the laser beams demagnified by the demagnification optical system with the optical fiber; wherein an Abbe number of each of the parallel light lenses is set to a set value suppressing an output fluctuation from the optical fiber to a predetermined value or less, the set value determined based on: a transverse magnification defined by a focal length of a corresponding one of the parallel light lenses, a demagnification of the demagnification optical system, and a focal length of the condenser lens; and a corresponding one of wavelength shifts of the laser beams generated by the laser light source.

Abstract: In one aspect of the present disclosure, improved end optics are disclosed that maximize the numerical aperture focused at a sample point while minimizing unwanted artifacts such as vignetting. The configurations also maintain centering of the excitation/collection beam on the objective if the probe tilts or bends. The disclosed configurations are particularly suited to probes wherein the excitation and/or collection paths between the probe and the laser/analyzer are coupled through multimode fibers, such as in Raman and other forms of laser spectroscopy. The disclosure includes the insertion of one or more additional lenses between the probe head and the focusing objective at the probe tip.

Abstract: A particle microscope includes a particle beam system directing a particle beam onto a sample. The particle beam system includes a magnetic lens energized by an adjustable lens current. The sample is positioned at an adjustable distance from the lens, and particles of the beam have an adjustable kinetic energy. A method of operating such microscope includes positioning a sample at a distance from the lens, adjusting the kinetic energy, changing the lens current at plural different lens current change rates, determining a lens current at focus for each of the plural different lens current change rates, and determining an optimized lens current based on the determined lens currents at focus and the lens current change rates.

Abstract: A light-emitting module is disclosed. The light-emitting module includes a condensing lens for condensing incident light into a space, a light source for providing first light to pass through the condensing lens, a first optical path conversion member for reflecting the first light to provide first reflected light to pass through the condensing lens, a second optical path conversion member for reflecting the first reflected light to provide second reflected light to pass through the condensing lens and a wavelength conversion unit for receiving the second reflected light, converting a wavelength of the received second reflected light, and radiating light the wavelength of which has been converted.

Abstract: An x-ray imaging system utilizes enhanced computing arrays. A plurality of x-ray illumination source positions are utilized to produce x-ray radiation at each of the x-ray illumination source positions and to project x-ray radiation towards an object. A detector detects x-ray radiation from the object and transmits detector images for each of the illumination source positions. A memory buffer stores the detector images from the detector. A graphics processing unit formats the detector images and constructs a complete frame data set with the detector images for each of the illumination source positions. Another graphics processing unit receives the complete frame data set and performs image reconstruction on the complete frame data set.

Abstract: A transparent coversheet intervenes between a lens and a thinned die in a visible light fault analysis tool so that the thinned die is robust to fractures. In addition, the transparent coversheet has a greater thermal mass than the thinned die and thus acts as a heat sink to prevent active circuitry in the thinned die from overheating during the visible light fault analysis.

Abstract: A near-field plate is a non-periodically patterned surface that can overcome the diffraction limit and confine electromagnetic fields to subwavelength dimensions. By controlling the interference of the electromagnetic fields radiated by the near-field plate with that of a source, the near-field plate can form a subwavelength near-field pattern in a forward direction, while suppressing fields in other directions, such as those reflected. The resulting unidirectional near-field plate may find utility in many applications such as high resolution imaging and probing, high density data storage, biomedical targeting devices, and wireless power transfer.

Abstract: An optical pickup device includes a semiconductor laser that emits a laser beam, and an object lens that concentrates the laser beam emitted from the semiconductor laser on an optical disc. In this optical pickup device, an optical axis of the object lens is inclined with respect to an optical axis of the laser beam that is incident on the object lens so as to generate flares caused by coma aberration on an entrance side in a forward direction of pits of the optical disc.

Abstract: A light-emitting module is disclosed. The light-emitting module includes a condensing lens for condensing incident light into a space, a light source for providing first light to pass through the condensing lens, a first optical path conversion member for reflecting the first light to provide first reflected light to pass through the condensing lens, a second optical path conversion member for reflecting the first reflected light to provide second reflected light to pass through the condensing lens and a wavelength conversion unit for receiving the second reflected light, converting a wavelength of the received second reflected light, and radiating light the wavelength of which has been converted.

Abstract: A projector includes a light source portion; and an optical scanning portion that scans light from the light source portion, wherein the light source portion comprises a first holder that holds a light source, and a second holder that holds an optical portion through which light from the light source is emitted, and the first holder and the second holder are arranged in that order from a light emitting direction.

Abstract: A monolithic integration of a plenoptic structure on an image sensor is provided using material with low refractive index on the substrate of photosensors and arranging material with a high refractive index on the material with low refractive index to create the plenoptic microlenses. Plenoptic lenses are created directly on the substrate of photosensors. Photosensors with a high integration density are arranged at minimum distances to minimize inter-pixel interferences and on the integration density end having “deformed square” geometries on the vertices adjacent to a pixel of the same color, removing any photosensitive area from the vertices. The light efficiency is increased by structures of plenoptic microlenses at variable distances from the substrate, with more asymmetric profiles on the periphery, or pixels of different sizes and shapes towards the periphery of the sensor. Micro-objectives are produced by the creation of alternate layers of low and high refractive index.

Abstract: A nonvolatile memory comprising at least one ferromagnetic region having permeability which changes from a first state to a second state of lower permeability upon heating; at least one laser operatively associated with the at least one ferromagnetic region which selectively provides heat to the ferromagnetic region to change its p permeability; and a plurality of connectors operatively connected to the at least one laser and adapted to be connected to a current source that provides a current which causes the laser to change the at least one ferromagnetic region from a first state to a second state. Optionally, the memory is arranged as an array of memory cells. Optionally, each cell has a magnetic field sensor operatively associated therewith. Optionally, the nonvolatile memory is radiation hard. Also, a method of recording data by heating at least one ferromagnetic region to change its permeability.

Abstract: The present disclosure discloses an information retrieval system evaluation method, device and storage medium. A ratio between the sum of all the related object parameters of a keyword in keyword in an evaluation retrieval result set and the sum of all the related object parameters of the keyword in keyword in a retrieval result set is used to compute a recall rate of an information retrieval system. And the recall rate is introduced to evaluate the information retrieval system, thereby enhancing accuracy of quantitative evaluation of the information retrieval system, and improving the automation degree of evaluation.

Abstract: A optical lens includes a lens body having a first surface and a second surface opposite to the first surface and having a recessed round shape in a cross-sectional view relative to an optical axis, a plurality of first support members protruded from the first surface at a first length, and a flange unit disposed at a lateral surface connected to the first surface, wherein the flange unit has a base portion.

Abstract: A system to control the focus of a mask-less lithographic apparatus, the apparatus including a projection system to project an image of a programmable patterning device onto a substrate. A first actuator system is configured to move at least one of the lenses of the projection system in a direction perpendicular to the optical axis of the projection system. A radiation beam expander is configured to project an image of the programmable patterning device onto the at least one lens. A second actuator system is configured to move the radiation beam expander in a direction parallel to the optical axis of the projection system in order to control the focus of the image projected onto the substrate.

Abstract: A device having an air bearing surface (ABS), the device including a near field transducer (NFT), the NFT having at least a portion thereof at the ABS; a first wrap layer, the first wrap layer surrounding at least a portion of the NFT, the first wrap layer having a thickness of not greater than about 30 nanometers (nm), and the first wrap layer being made of a material that has a refractive index (n) that is not greater than 2.0; a second wrap layer, the second wrap layer surrounding at least a portion of the first wrap layer, the second wrap layer having a thickness that is not greater than 100 nm, and the second wrap layer being made of a material that has a refractive index (n) that is at least about 1.9; and a top cladding layer surrounding at least a portion of the second wrap layer, the top cladding layer being made of a material that has a refractive index (n) that is not greater than 2.0.

Abstract: According to an embodiment, a microprobe includes a base and a lever. The base includes a first electrode provided on a surface thereof. The lever is supported by the base and includes a second electrode and a third electrode. The second electrode is connected between the first electrode and the third electrode. The third electrode is formed to project from the second electrode in a first direction in a main surface of the lever. A width of the third electrode in a second direction perpendicular to the first direction in the main surface defines a width of an electrical contact area when a scanning operation is performed by use of the third electrode in a third direction perpendicular to the main surface.

Abstract: An image forming apparatus includes an automatic document feeder to feed an original document downstream, a frame, an image reader to read the original document fed by the automatic document feeder, and an image reader mounting unit to hold the image reader thereon. The frame pivotally supports the image reader mounting unit. A parallelism adjusting unit is provided to adjust parallelism of the image reader mounting unit. The parallelism adjusting unit is disposed on a side opposite a pivoting center for the image reader mounting unit at a prescribed interval therefrom. The pivoting center is located near a reading reference point in the image reader, at which the image reader starts reading the original document in main and sub-scanning directions.

Abstract: There is provided an recording apparatus including a light irradiation unit, a reference-plane tracking control unit, a recording unit that executes recording on the recording medium by independently modulating first and second recording beams when the recording beams radiated by the first and second objective lenses are designated as the first and second recording beams, respectively, a recording-layer tracking control unit that performs tracking control of the first objective lens based on reflected light of a first servo beam and tracking control of the second objective lens based on reflected light of a second servo beam when the servo beam radiated by the first objective lens is designated as the first servo beam and the servo beam radiated by the second objective lens is designated as the second servo beam, and a control unit that controls the reference-plane tracking control unit, the recording-layer tracking control unit, and the recording unit.

Abstract: Provided are a method and apparatus for focusing a laser beam on an optical disc. According to various aspects, the apparatus may include an objective lens which has a numerical aperture below what is standardized for the optical disc. In addition, a collimating lens which is used to focus a laser beam on the objective lens may be positioned at a fixed location. Despite the fixed location, the apparatus may support data recording/reproducing on multiple layers of the optical disc.

Abstract: A system and method for providing direct read after write functionality in an optical data storage device include an optical head having a first coherent light source modulated at higher power during writing of data to the optical medium and a second coherent light source operating in a continuous wave mode at lower power while the first coherent light source is writing data. Optic components combine light from the first and second light sources and focus light from the first coherent light source to a first spot of a selected track on the optical medium and focus light from the second coherent light source to a second spot on the selected track downstream from the first spot relative to movement direction of the optical medium to read and verify the data directly after writing during the write process rather than in a separate verification process.

Abstract: There is provided a playback device including a light source, an objective lens that radiates light emitted onto an optical recording medium, and onto which is incident reflected light obtained from a recording surface of the optical recording medium, a condenser lens that condenses the reflected light, a photodetecting section configured to, provided that a confocal position is a focal position of the condenser lens, ? is a wavelength of light radiated onto the optical recording medium, and NA is a numerical aperture of the objective lens, extract and detect light within a range of a diameter less than 1.5?/NA centered on an optical axis at the confocal position, and a phase difference imparting section that imparts a designated phase difference between a reflected light component from a readout track and a reflected light component from a track neighboring the readout track.

Abstract: An objective lens unit according to the present invention includes a first objective lens 41; and a first lens holder 2 for supporting the first objective lens 41. The first lens holder 2 is formed of a material which transmits ultraviolet. Preferably, the first lens holder 2 includes a through-hole, having first and second openings 2a and 2b, through which light incident on the first objective lens 41 passes, and an opening limiting section 3 provided along a circumferential direction of the through-hole and projecting toward a central axis of the through-hole. The first objective lens 41 is supported so as to block the first opening 2b. The opening limiting section 3 guides light incident thereon from the second opening 2a in a direction away from an optical axis of the first objective lens.

Abstract: An optical pickup device moves in a feed direction parallel to a radial direction of an optical disc rotating on an axis of rotation, and records or reproduces information on an information recording surface of the optical disc. The optical pickup device has a first light source that emits light of a first wavelength, a second light source that emits light of a second wavelength differing from the first wavelength, a first objective lens for focusing the light from the first light source onto the information recording surface, and a second objective lens for focusing the light from the second light source onto the information recording surface. The first and second objective lenses and the first light source are disposed in a plane that passes through the axis of rotation and is parallel to the feed direction.

Abstract: The invention provides an optical pickup device that ensures complete curing of adhesive when a tilt adjusting holder is glued to an objective lens holder. The optical pickup device comprises: a light source; an objective lens for focusing light emitted from the light source onto an optical storage medium; a tilt adjusting holder to which to secure the objective lens; and an objective lens holder to which to glue the tilt adjusting holder. The objective lens holder includes: adhesive joint sections for securing the tilt adjusting holder to the objective lens holder using an adhesive; a seat section on which the tilt adjusting holder abuts; and adhesive anti-overflow pockets, located between the adhesive joint sections and the seat section, for receiving the adhesive when the adhesive flows from the adhesive joint sections.

Abstract: An optical information recording/reproducing optical system where resin material has Tg>115° C., first, second and third films are on an optical disc side of an objective lens and surfaces of an optical element, respectively, a light source side of the objective lens has a fourth film having four or more layers not containing Ti, each of the first, second and third films includes a non-high refractive index layer made of one of silicon oxide, aluminum oxide, aluminum fluoride and magnesium fluoride or a mixture of at least two of them, each of the first, second and third films is not made of one of Ti, Ta, Hf, Zr, Nb, Mo and Cr, a layer of the fourth film closest to a base material is the non-high refractive index layer. The fourth film satisfies 350<?max(2)<420 and 600<?min(2)<750, and reflectivity thereof decreases monotonously.

Abstract: In order to achieve further cost reduction while the package size of an optical pickup having two objective lenses and the restriction on the disposition of the two objective lenses are maintained, an optical system for laser light emitted from a red/infrared dual-wavelength laser diode is disposed such that a parallel plate beam splitter is disposed to be inclined with respect to the optical axis of focused light of the laser light reflected by an optical disk and the optical axis of the laser light between a rising mirror and the parallel plate beam splitter is inclined from the signal track direction of the optical disk. The laser light to which astigmatism is given by transmission through the parallel plate beam splitter is caused to be directly incident on a light detector without passing through an astigmatism adjustment optical element.

Abstract: An optical pickup device, an optical drive using the same, and a method of forming a beam spot are provided. The optical pickup includes a light source system that includes a light source corresponding to at least one of a digital versatile disc (DVD) and a Blu-ray disc (BD). The light source forms a beam spot having an oval shape with a long axis and a short axis on an information recording track of the disc, and the light source is disposed such that the long axis is maintained at an angle ranging from 0° to 30° with respect to a radial direction passing through a rotation center of the disc.

Abstract: It is an object of the present invention to record to and reproduce different types of optical disks using light beams with different wavelengths. In an optical head device for recording to and reproducing high-density optical disks using an objective lens with a large NA, a sawtooth-shaped hologram is used for recording to and reproducing conventional optical disks such as DVDs. For blue light, a sawtooth height is the light path length 2?, and second-order diffraction light is used. Red light generates first-order diffraction. The hologram is blazed and has convex lens function, and corrects chromatic aberration of the refractive lens.

Abstract: Provided are an optical pickup and an optical system employing the optical pickup. The optical pickup includes a twin light source. In various aspects, a length between the two light sources of a twin light source is reduced while the magnification of the optical pickup is increased, in comparison to a conventional optical pickup. Accordingly, a manufacturing cost of the optical pickup may be reduced.

Abstract: Provided is an objective lens, which is provided in an optical pickup including a spherical aberration correction mechanism which performs a spherical aberration correction with respect to laser light applied to a recording layer of an optical recording medium, having the recording layer on which information can be recorded at a plurality of positions in a depth direction, via the objective lens, and a tilt correction unit which varies a lens tilt angle which is a tilt angle of the objective lens, thereby performing a tilt correction.

Abstract: An optical information recording and reproducing apparatus includes an irradiation unit of a signal light beam and a reference light beam required for data recording, and a cure irradiation unit having at least one of a pre-cure irradiation that irradiates a predetermined light beam on to a desired position prior to irradiating the reference light bean and the signal light beam on to the desired position when information is recorded in the desired position on an optical information recording medium and a post-cure irradiation that irradiates a predetermined light beam on to the desired position so as to make the desired position non-recordable after the information is recorded in the desired position on the recording medium. The cure irradiation unit is disposed in one driving device in a freely movable manner in the driving device.

Abstract: A method and an apparatus for reading data from or writing data to an optical recording medium is described, the data being stored as marks having different lengths. Marks having a length below the limit of diffraction at a first wavelength are read or written with the first wavelength, whereas marks having a length above the limit of diffraction at the first wavelength are read or written with a second wavelength larger than the first wavelength.

Abstract: An optical disk driving apparatus includes an optical head device having a laser light source, a converging optical system converging a light beam emitted by the laser light source onto an optical disk, a photo detector receiving reflected light reflected by the optical disk, and an aberration correcting optical system controlling aberration of the converging optical system; a motor rotating the optical disk; and a control section receiving a signal from the photo detector, wherein the converging optical system has an objective lens formed using resin as a main material, the aberration correcting optical system has a spherical aberration correcting element correcting spherical aberration, and the control section evaluates quality of a reproduction signal for information in the optical disk by using the reflected light received by the photo detector, and utilizes a result of the evaluation to perform closed loop control on the spherical aberration correcting element.

Abstract: An optical pickup, an optical disk drive device, an optical information recording device, and an optical information reproduction device in which a reproduction signal, a focus error signal, and a gap error signal can be detected with high accuracy when information is recorded/reproduced on/from an optical information medium having a plurality of information recording layers.

Abstract: According to one embodiment, an optical pickup configured to record and to reproduce on a layer of a disk, including, a light source configured to emit a laser beam, an objective lens including a variable use magnification and configured to focus the laser beam on the layer, a collimator lens configured to change the magnification of the objective lens by moving along an optical axis direction, and a liquid crystal module configured to generate spherical aberration to cancel a coma aberration which may occur because an object point and an image point of the objective lens at the use magnification do not exist on an optical axis of the objective lens.

Abstract: An optical disc apparatus records information onto plural disc shaped mediums of different standards or reproduces information from the plural disc shaped mediums. The optical disc apparatus includes an optical pickup equipped with a spherical aberration correcting unit using a movable lens, and a disc insertion unit for inserting and ejecting the disc shaped mediums. The spherical aberration correcting unit starts the movement of the movable lens to an initial position while the disc insertion unit inserts or ejects the disc shaped medium. As such, the present invention discloses the optical disc apparatus with a reduced disc recognition time for improving user convenience and a driving method thereof.

Abstract: An optical pickup device, which can effectively prevent occurrence of trouble in recording and reproducing of information due to the fact that an objective lens for each optical beam is contaminated while not adding unnecessary parts and while reducing a cost, is provided. An optical pickup device (P1) which performs the recording or reproducing of information in or from an optical disc (13) by using an optical beam (B) or (D), comprises: objective lenses (11) and (12) on which cleaning films which are activated by radiation of the optical beam (B) and clean their surfaces are formed in an optical path, and a control unit (15) for setting an optical path of the optical beam (B) in such a way that the optical beam (B) reflected by the optical disc (13) is radiated on the objective lens (12).

Abstract: An optical head, an optical disc device and an information processing device are capable of suppressing the amount of third-order astigmatism created upon recording or reproducing information on or from a multi-layer optical disc including at least three information recording surfaces. An objective lens satisfies a relationship of tc>(t0+tn)/2 assuming that t0 denotes the thickness of a light transmitting layer from the outer surface of the multi-layer optical disc to an information recording surface having the largest light transmitting layer thickness, tn denotes the thickness of a light transmitting layer from the outer surface of the multi-layer optical disc to an information recording surface having the smallest light transmitting layer thickness and tc denotes the thickness of a virtual light transmitting layer at which the absolute value of a third-order spherical aberration is minimum when blue-violet laser light is incident as parallel light on the objective lens.

Abstract: A recording and reading system for a multi-layered optical recording medium includes: a multi-layered optical recording medium including a plurality of recording layers and a single servo layer; and an optical head. The optical head includes a recording and reading objective lens of a signal recording and reading optical system and a servo objective lens of a servo signal detection optical system that are disposed on a common actuator. The recording and reading objective lens is mounted on the common actuator through a minute-drive apparatus so as to be minutely driven in a focusing direction relative to the servo objective lens. When the servo objective lens is focused on the servo layer, a reading light beam is quickly focused on a target one of the plurality of recording layers.

Abstract: An optical disk discriminating method and an optical disk device which can detect reflected rays for making discrimination among kinds of optical disks with high accuracies. By switching a plurality of lasers and moving a spherical aberration corrector while moving an objective lens to cause it to approach or keep away from an optical disk, rays reflected light from the optical disk can be detected with high accuracies. Discrimination among the kinds of a plurality of optical disks can be made on the basis of signals generated from the detected reflected rays. This ensures that the kind of an optical disk can be determined through one operation of sweeping.

Abstract: A low cost and lightweight interchangeable lens system is provided. The lens system includes two aspheric elements that is usable both for page-based and bit-based data storage systems. The lens system has a large field of view up to ±50 degrees and a high numerical aperture up to 0.8. The invention reduces cost and weight of the objective lenses and is usable with the servoing technology. The invention provides a long working distance of 20% of the focal length and provides sufficient physical space to accommodate media and aberration corrections, which enable a media interchangeable and compatible system among the both optical recording formats.

Abstract: An optical-pickup apparatus includes: a first-objective lens; a second-objective lens; a lens holder including a first-lens barrel having the first-objective lens mounted on an end face thereof and a second-lens barrel having the second-objective lens mounted on an end face thereof; an actuator unit having the lens holder mounted thereon; and a housing having the actuator unit mounted thereon, the first and second objective lenses each being mounted on the lens holder such that a direction, in which wavefront of coma aberration on each lens face is most advanced in phase, is aligned with a radial direction of an information-recording medium, the actuator unit being mounted on the housing such that an optical axis of the first-objective lens is inclined in the radial direction at an inclination angle of the axis toward a recording surface of the medium required to cancel coma aberration of the first-objective lens to the surface.

Abstract: An optical pickup device includes a first optical system and a second optical system. The first optical system and the second optical system each include a mirror member that reflects light from a light source to change a direction of propagation of the light to a direction substantially perpendicular to the information storage surface of an optical disc. The first optical system and the second optical system are arranged such that a direction in which light from a first light source enters a first mirror member is substantially perpendicular to a direction in which light from a second light source enters a second mirror member.

Abstract: An objective lens unit according to the present invention includes a first objective lens 41; and a first lens holder 2 for supporting the first objective lens 41. The first lens holder 2 is formed of a material which transmits ultraviolet. Preferably, the first lens holder 2 includes a through-hole, having first and second openings 2a and 2b, through which light incident on the first objective lens 41 passes, and an opening limiting section 3 provided along a circumferential direction of the through-hole and projecting toward a central axis of the through-hole. The first objective lens 41 is supported so as to block the first opening 2b. The opening limiting section 3 guides light incident thereon from the second opening 2a in a direction away from an optical axis of the first objective lens.

Abstract: When performing recording/reproduction of information for a given recording layer of an optical disc having three recording layers, influences of reflected light from other recording layers are reduced or removed, thus making it possible to obtain a more stable RF signal or focus error signal. An optical pickup device includes a light source, a collimator lens, an objective lens, a photodetector, and a light shielding member. Among the recording layers of the optical disc, a first layer and a second layer adjoining each other are disposed in the order of the first layer and second layer from near the objective lens.

Abstract: An optical pickup has an objective lens that is shared for light of three wavelengths. The effective diameter of the light that passes through the objective lens decreases in a sequence of the light of a first wavelength (light for a first optical disk), the light of a second wavelength (light for a second optical disk) and the light of a third wavelength (light for a third optical disk); and the light of the third wavelength is incident on the objective lens in a finite system. The objective lens is provided so that the focal distance of the light of the second wavelength is greater than the focal distance of the light of the first wavelength.

Abstract: The present invention relates to an optical device which includes a first laser diode, a beam splitter, a first objective lens, a photo-detector, a second laser diode, a wedged plate beam splitter, a second objective lens and a collimator. The present invention deploys two independent transmitting paths. The retrieving paths share the beam splitter and the photo-detector commonly at the returning route.