Abstract: Among other things, a variable diaphragm is described for a lighting device and/or for an observation device inside an optical observation apparatus for imaging an object and/or an intermediate image produced by an object, particularly for a stereoscopic observation apparatus, wherein the variable diaphragm is provided for at least one beam path of the lighting device and/or for a beam path of the observation device. According to the invention, the variable diaphragm can be controlled in order to produce a specific lighting geometry by regions. In addition, the variable diaphragm is formed for the utilization of all directions of polarization of the light of a light source. Further, a lighting device, an optical observation device, as well as an optical observation apparatus are also described.

Abstract: An optical device for providing prescription correction to a mirror so that a person who normally wears prescription glasses may clearly see, and also have unobstructed access to, their face in order to apply makeup. A magnifying lens in the form of an eyeglass blank of an appropriate corrective power is removably attached to the mirror by means of a suction cup and a hook element. The magnifying lens has a hole joining its two refracting surfaces. One end of the hook element fits through the hole and the other end of the hook element is attached to the suction cup. The lens situated in close proximity to the mirror provides a user who normally wears prescription eyeglasses with the appropriate corrective power to enable them to clearly see their face while providing good working room for them to perform tasks such as applying their makeup.

Abstract: A MEMS-based display device is described, wherein an array of interferometric modulators are configured to reflect light through a transparent substrate. The transparent substrate is sealed to a backplate and the backplate can contain electronic circuitry for controlling the array of interferometric modulators. The backplate can provide physical support for device components, such as electronic components which can be used to control the state of the display. The backplate can also be utilized as a primary structural support for the device.

Abstract: A light pipe based projection engine includes a X-prism transmitting substantially light of a useful polarization in an output direction and reflecting substantially light of a non-useful polarization in a first orthogonal direction substantially orthogonal to the output direction. An initial reflector may reflect the non-said low, said medium, and said high bands of wavelengths in a second orthogonal direction substantially orthogonal to the output direction and the first orthogonal direction, and a final reflector may reflect the non-said low, said medium, and said high bands of wavelengths in the output direction. The non-said low, said medium, and said high bands of wavelengths may be rotated substantially to light of the useful polarization by the initial and final reflectors.

Abstract: A spatial light modulator has an array of elements organized into element rows and element columns and an array of electrodes organized into electrode rows and electrode columns to activate the array of elements. The modulator has pixel circuitry organized into circuit rows and circuit columns with the pixel circuitry being electrically coupled to the array of electrodes, such that there is at least one translation of either circuits in a column to electrodes in a row or circuits in a row to electrodes in a column.

Abstract: A microelectromechanical device (MEMS) utilizing a porous electrode surface for reducing stiction is disclosed. In one embodiment, a microelectromechanical device is an interferometric modulator that includes a transparent electrode having a first surface; and a movable reflective electrode with a second surface facing the first surface. The movable reflective electrode is movable between a relaxed and actuated (collapsed) position. An aluminum layer is provided on either the first or second surface. The aluminum layer is then anodized to provide an aluminum oxide layer which has a porous surface. The porous surface, in the actuated position, decreases contact area between the electrodes, thus reducing stiction.

Abstract: A flexible electro-optic display comprises a layer of solid electro-optic material; a backplane comprising at least one electrode arranged to apply an electric field to the layer of electro-optic material; and an adhesive layer disposed between the layer of electro-optic material and the backplane and adhesively securing the layer of electro-optic material to the backplane, the adhesive layer having a storage modulus (G?) of at least about 104 Pascals at 10?3 Hz and 70° C.

Abstract: A wavefront sensor for measuring a wavefront contains an array of lenslets, a detector array, and a mask having a temporally fixed pattern containing one or more opaque regions that are substantially opaque to light from the wavefront. The mask comprises one or more transmissive regions that are transmissive of light from the wavefront. The mask and the array of lenslets are disposed such that light from the wavefront that is transmitted by the transmissive regions is focused by onto the detector array by the array of lenslets. The mask is adapted to be selectably disposed to any one of a plurality of predetermined positions, wherein a different group of lenslets from the array focuses light from the wavefront onto the detector array depending on which of the plurality of predetermined positions is selected.

Abstract: A MEMS device includes a hinge that is disposed outwardly from a substrate and capable of at least partially supporting a conductor that is disposed outwardly from the hinge. The conductor being capable of pivoting about a first axis. The device also includes one or more electrostatic fins that are disposed inwardly from and in contact with the conductor. The one or more electrostatic fins being disposed substantially along a second axis that is different than the first axis. The MEMS device further includes one or more electrodes that are formed outwardly from the substrate and inwardly from the conductor. The one or more electrodes being separated from the conductor by a first air gap. The one or more electrodes also being separated from the one or more electrostatic fins by a second air gap that is different than the first air gap.

Abstract: The invention relates generally to cognitive stimulation apparatuses and systems, and methods of manufacturing the same. In certain exemplary implementations the invention provides an at least partially transparent, pliable gel having an optical property, such as brightness or color, and a circuit for delivering electromagnetic radiation to the gel to modify the optical property. Under certain conditions, modifying the optical property can stimulate a user's visual and other senses to help improve cognitive development and functionality.

Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.

Abstract: An optical fiber for Raman amplification amplifies a signal light with a pumping light. A chromatic dispersion at a wavelength of 1,550 nm is in a range between ?70 ps/nm/km and ?30 ps/nm/km. Raman gain efficiency with a pumping light of 1,450 nm is equal to or more than 5 (W×km)?1. Nonlinear coefficient at the wavelength of 1,550 nm is equal to or less than 5.0×10?9 W?1. Zero-dispersion wavelength is neither at a wavelength of the signal light nor at a wavelength of the pumping light. Cut-off wavelength is equal to or less than the wavelength of the pumping light.

Abstract: Optical transmission systems including a plurality of optical amplifiers configured to provide optical amplification of one or more information carrying optical signal wavelengths. At least two of the optical amplifiers are operated to provide net losses or net gains along corresponding spans, while the cumulative gain provided by the plurality of optical amplifiers substantially compensates for the cumulative loss of the spans.

Abstract: Methods and systems for providing brightness control in an interferometric modulator (IMOD) display are provided. In one embodiment, an interferometric modulator display pixel is provided that includes a microelectromechanical systems (MEMS) interferometric modulator having an associated first color spectrum, and a color absorber located substantially in front of the interferometric modulator display pixel, in which the color absorber has an associated second color spectrum. The microelectromechanical systems (MEMS) interferometric modulator is operable to shift the first color spectrum relative to the second color spectrum to control a visual brightness of the interferometric modulator display pixel independent of a color of the interferometric modulator display pixel.

Abstract: The disclosed embodiments combine an electrothermal actuator system with an electrostatic attraction system, in order to orient bistable micromirrors in digital micromirror devices (DMDs). The micromirror, pivotally supported, can switch between two orientations. While typical DMD systems use electrostatic electrodes to orient the micromirror, stiction forces can restrict micromirror motion, affecting optical performance. The disclosed embodiments use an electrothermal actuation system to mechanically assist the electrodes, overcoming stiction without the need for a high-voltage reset pulse.

Abstract: A viewing device for minimizing the distance between interpupillary viewpoints of the left and right eyes to effect biocular viewing or minimized viewpoints viewing by partially reflecting the view of one eye to the other eye or by partially reflecting the view near one eye to the other eye through a series of reflectors starting with the flat semi-silvered mirror (20) that partially reflects light towards the roof mirror (22 and 26) and concave mirror (24) combination that reflects an erect and focused image that is then received by the entry parabolic mirror (28) that collects light about the center of the converging mirror and reflects it towards the facing exit parabolic mirror (30) and finally reflecting and converging the light to the pupil of the other eye.

Abstract: An image display projector and a method of displaying images are provided so as to enable reducing the occurrence of scintillation. The image display projector comprises: an optical engine for emitting light according to an inputted imaging signal; a Fresnel lens disposed to receive the light emitted from the optical engine, for emitting the incident light as collimated one; a diffusion member, placed in a position frontal to the Fresnel lens in the light-traveling direction, for emitting diffused light, by diffusing the collimated light emitted from the Fresnel lens; and a drive unit for moving either the Fresnel lens or the diffusion member, along a predetermined track (orbit), in a plane parallel to either the one from which the collimated light is emitted or the one from which the diffused light is emitted. And then, the moving velocity of either the Fresnel lens or the diffusion member is at any moment larger than zero in any direction within the parallel plane.

Abstract: In a stereoscopic display apparatus having optical directory elements such as lenticular elements (4) extending parallel to each other and being slanted at an angle to one of the rows and columns of picture element the picture elements (2) are positioned out of focus at the optical directory elements, in such a manner that the modulation depth of “dark bands” is minimized.

Abstract: Methods and systems are described herein which produce polarization-independent full color images suitable for rear-projection television sets and other multimedia displays. The system uses illumination with R, G, B light from two different light sources for each color. A viewer wears glasses with narrowband optical filters, preferably holographic filters. The R, G, B light from the light sources is slightly offset at each of the 3 emission wavelengths, with one set of R, G, B light being filtered by the holographic filter in front of the left eye of the, and the other set of R, G, B light being filtered by the holographic filter in front of the viewer's right eye.

Abstract: There is provided an antistatic laminate that can simplify the production of a polarizing plate and, at the same time, can satisfactorily meets requirements of IPS and VA modes. The antistatic laminate is adapted for use in polarizing plates and comprises a light transparent base material and an antistatic layer provided on said light transparent base material. The antistatic layer is not located on the upper part or above a polarizing element in said polarizing plate.

Abstract: A method of producing an optical film comprising at least two ionizing radiation-curing layers on a transparent substrate, the method comprising: Step 1 of irradiating a layer A, which comprises two or more kinds of polymerization initiators having different absorption ends at a longer wavelength side in wavelength range of sensitivity to which they are sensitive, with an ionizing radiation having a wavelength to which at least one kind (a) of the polymerization initiators is not substantially sensitive and at least one kind (b) of the polymerization initiators is sensitive; and Step 2 of spreading a coating solution for layer B comprising at least one polymerization initiator (c) over the layer A after Step A and then irradiating the coating solution for layer B with an ionizing radiation having a wavelength to which the polymerization initiators (a) and (c) are sensitive.

Abstract: This invention relates to an optical element comprising a first component having a birefringence dispersion of D1>1, and a second component having a birefringence dispersion of D2>1 and a maximum peak absorption at a wavelength less than 400 nm, wherein the birefringence ratio at any wavelength of the first and second component is ?n1/?n2<0, and wherein the optical element has a reverse birefringence dispersion of D<1.

Abstract: A colored anti-fog mirror that emits reflected light in response to incident light, the colored anti-fog mirror comprising a substrate, a hydrophilic functional layer containing a photocatalytic substance, and a metallic reflecting film provided between the substrate and the hydrophilic functional layer, wherein a material of the metallic reflecting film and a thickness of the hydrophilic functional layer are set such that the reflected light has a spectral reflection spectrum having a maximum reflectance in the visible region over 510 nm and not more than 600 nm.

Abstract: A security Device comprises a zero order diffractive microstructure (5) buried within a substrate (3). One or more further optical structures, such as 5 microlenses (1), may be formed on a surface (2) of the substrate (3). The further optical structures modify the optical characteristics of the zero order diffractive microstructure (5). Various alternatives or additional optical structures and methods of producing them are described in additional embodiments.

Abstract: An optical assembly for a projection illumination system has a refractive lenses and a diffractive lens for imaging a sheet of light from a light source onto a Spatial Light Modulator (SLM). One embodiment utilizes a fresnel lens having kinoforms formed on a surface. Such a lens may be molded using a light-weight plastic in a single step.

Abstract: A fabricating method for optical multilayer thin film structure is disclosed wherein a QWOT stacked film structure is formed on a substrate from which a deposition rate is analyzed, and a non-QWOT stacked film structure is formed using the analyzed deposition rate, and the analyzed deposition rate is applied to the non-QWOT stacked film structure, and wherein thin film thickness control layers having a QWOT are periodically formed on an optical multilayer thin film structure and a deposition rate thereof is applied to a non-QWOT stacked film structure fabricated thereafter, such that thickness of a non-QWOT stacked film structure can be accurately controlled and a multilayer bandpass filter having a pass band desired by an optical device can be embodied.

Abstract: A display apparatus (100) comprise a display section (110) that displays image on a display screen; a viewer position reading section (520) that reads a relative position of at least one viewer with respect to the display screen; a glare detection section (111 to 114) that detects light reflected from external light toward the viewer to output the detected result as glare information; and an image quality correction section (500) that corrects image quality of the display section based on the glare information outputted by the glare detection section.

Abstract: A light-absorbing member has a substrate (101, 111) made of a material capable of absorbing light of which reflection is to be prevented, and an antireflection structure (102, 112, 303) having structural elements arranged on the surface of the curve in an array form at a period smaller than the wavelength of the light. The substrate having the shape of a curve viewed from a macroscopic viewpoint. The structural elements have a shape protruding or being recessed from a reference face corresponding to the curve of the substrate, and are arranged so that the straight lines connecting the reference face to the tips of the respective structural elements are nearly parallel to one another.

Abstract: A micro-lens and a method for forming the micro-lens is provided. A micro-lens includes a substrate and lens material located within the substrate, the substrate having a recessed area serving as a mold for the lens material. The recessed can be shaped such that the lens material corrects for optical aberrations. The micro-lens can be part of a micro-lens array. The recessed area can serve as a mold for lens material for the micro-lens array and can be shaped such that the micro-lens array includes arcuate, non-spherical, or non-symmetrical micro-lenses.

Abstract: Now, according to the present invention, dichroic filters are provided that incorporate a flexible polymer film substrate, such as poly(ethylene naphthalate), onto which a dielectric and/or reflective metal stack has been formed. Filters of the present invention are durable, flexible, and lightweight, and can be advantageously used in many specialty lighting applications.

Abstract: The present invention relates to an optical glass having a refractive index (nd) of greater than or equal to 1.65 and an Abbé number (? (nu)d) of greater than or equal to 50 for use in precision press molding. The glass exhibits that a ratio ? (alpha)1/? (alpha)2 is less than 17 when temperature denoting maximum value of differential in amount of elongation of glass relative to temperature differential DELTAT (where DELTAT denotes a constant value of 1° C. or less) over a temperature range from glass transition temperature (Tg) to sag temperature (Ts) is denoted as T1, average coefficient of linear expansion over a range from T1-5° C. to T1+5° C. is denoted as alpha1, and average coefficient of linear expansion over a range from the glass transition temperature (Tg)?160° C. to the glass transition temperature (Tg)?140° C. is denoted as alpha2.

Abstract: Refractive projection objective with a numerical aperture greater than 0.7, consisting of a first convexity, a second convexity, and a waist arranged between the two convexities. The first convexity has a maximum diameter denoted by D1, and the second convexity has a maximum diameter denoted by D2, and 0.8<D1/D2<1.1.

Abstract: A liquid lens for adjusting a focal length by electro-wetting. A body houses a non-conductive fluid and a conductive fluid therein. A cover is capped on the body. A first adhesive bonds the body to the cover, the first adhesive curing rapidly. Also, a second adhesive bonds an outer periphery of the body to an outer periphery of the cover. The glass cover and the body are bonded across a large area by two types of adhesives with different compositions. This allows the lens manufactured to greatly withstand temperature and heat impact and stay durable in a high-temperature humid environment, thereby significantly elevating a quality of the final product.

Abstract: A liquid lens having a curved contact surface with inner fluids. The liquid lens is configured to adjust a focal distance using electro-wetting and includes a base having an insulator film formed thereon and connected with an electrode. The liquid lens also includes a first fluid disposed on the base and a second fluid disposed on the first fluid. The liquid lens further includes a cover for hermetically sealing the first and second fluids, the cover connected to the electrode and made of a light-transmitting material. According to the present invention, the curvature of a meniscus between the fluids is allowed to change sensitively or insensitively in response to voltage. This allows application of the liquid lens to various electronic devices and a miniaturized structure with a small thickness.

Abstract: Zoom lens systems and methods for imaging incoming rays over a range of ray angles are disclosed. The incoming rays are characterized by at least phase. The zoom lens system includes an optical axis and is characterized by a plurality of modulation transfer functions (MTFs) corresponding at least to the range of ray angles. The zoom lens system includes an optical group disposed along the optical axis, including at least one variable optical element that has a variable focal length selectable between at least two distinct focal length values. The optical group also includes a wavefront coding element. The wavefront coding element alters at least the phase of the incoming rays, such that the plurality of MTFs corresponding to the range of ray angles, for each one of the two distinct focal length values, are less sensitive to misfocus-like aberrations than a corresponding system without the wavefront coding element.

Abstract: A zoom lens, including: a first group optical system having a negative focal length; a second group optical system having a positive focal length; a third group optical system having a positive focal length, the first group optical system, the second group optical system and the third group optical system being arranged in this order from an object side to an image side; and an aperture stop configured to move together with the second group optical system and disposed on the object side of the second group optical system, a change in magnification being carried out by decreasing a space between the first group optical system and the second group optical system when the change in magnification is carried out from a short focal length end to a long focal length end.

Abstract: A zoom optical system mountable in an ultra-small camera module. A first lens group is disposed stationary and has a negative refractive power. The first lens group includes at least one lens and a prism for converting the paths of light incident through the lens. A second lens group is disposed movable to execute zooming and has a positive refractive power. A third lens group is disposed stationary and has a positive refractive power. The third lens group includes a liquid lens having a meniscus formed between non-miscible first and second liquids, the first liquid having conductivity and polarity. The meniscus is changed in its radius of curvature in response to voltage application and functions as a refracting surface, by which the third lens group corrects an image plane in accordance with zooming by the second lens group. This allows optimal zooming capacity with high resolution and superior aberrational characteristics.

Abstract: An optical unit of a laser module is installed at front end of a laser diode of a drive circuit board. The optical unit includes a sleeve that is integrally injection molded from plastic material. Moreover, an optical lens is formed at the top of the sleeve. The inner wall of the sleeve is provided with a focus adjusting slope facing the laser diode. In this way, the problems of the prior art with respect to the high material and assembly cost can be resolved by the invention. In other words, the invention ensures the simplification of elements and the reduction of material and assembly cost.

Abstract: A reflective objective is disclosed, in which essentially all the optical power is in a single, off-axis, concave mirror, which is oriented generally perpendicular to the central axis of the objective. An incident beam is directed to and from the concave mirror by a pair of flat mirrors, so that a central on-axis ray in the incident beam is collinear with the corresponding thrice-reflected ray at the object. The object is one focal length away from the concave mirror. The aperture stop is also one focal length away from the concave mirror, leading to a condition of telecentricity at the object. Different focal lengths for the objectives are realized by using mirrors with different curvatures, located at different distances away from the central axis of the objective. The reflective objective can optionally be retrofitted into a turret typically used for microscope objectives, and can optionally have refractive elements, making the objective catadioptric.

Abstract: A display device for displaying information is provided with an optical system for guiding the light of the display device to the eye, the optical system having, in the order in the proceeding direction of the light, an entrance face for receiving the light, a curved face for totally reflecting the light and a reflecting face concave to the eye side and adapted to reflect the light toward the eye. The reflected light is transmitted by the curved face and reaches the eye. Thus there is obtained a compact display device with satisfactorily suppressed aberrations.

Abstract: An electro-optical device includes a first substrate; a second substrate; an electro-optical material, the electro-optical material being disposed between the first and second substrates; prismatic portions that collect light incident on the first substrate, each prismatic portion being in the form of a groove having an opening, disposed in the first substrate, and being adjacent to the electro-optical material; a functional layer that drives the electro-optical material, the functional layer being disposed on a side of the first substrate, the side being adjacent to the electro-optical material; and the functional layer extending over the openings; and first light-shielding portions disposed on the second substrate, each light-shielding portion overlapping a corresponding one of the prismatic portions when viewed in plan.

Abstract: A convex mirror assembly includes convex mirror and a back board, wherein each of the convex mirror and the rear box has a bent portion and a positioning ring encloses the bent portions. The positioning ring is composed of a plurality of sections and each section has a substantially C-shaped cross section which has an enclosing portion, a covering portion and a support potion extending transversely from a first end and a second end of the enclosing portion. Two respective distal ends of the bent peripheries are in contact with the support portion. The covering portion has an overlapping portion on a first end thereof and an engaging portion on a second end thereof, so that the overlapping portion of a first section is sized to overlap on the engaging portion of a second section next to the first section.

Abstract: An optical low pass filter includes: a light transmitting member (41); and a refractive index distribution generation means (42) that generates a refractive index distribution cyclically changing within the plane of the light transmitting member (41). The refractive index distribution generation means includes a piezoelectric element, for example, and generates the refractive index distribution by generating the compressional wave in the light transmitting member (41) with a high frequency voltage being applied to the piezoelectric element.

Abstract: When copying servo information from an electro-magnetic field copy master to a vertical storage medium, the magnetization direction of the vertical storage medium is made to the direction the reverse of an external electro-magnetic field applied to the vertical storage medium and the electro-magnetic field copymaster, the vertical storage medium is closely touched on the electromagnetic field copy master provided with a substrate which has concavity/convexity corresponding to the servo information and at least the convex part of which of the concavity/convexity is made of a softly magnetic material and a conductor installed in the concave part of the substrate and an external electro-magnetic field stronger than the coercive field strength of the vertical storage medium is instantaneously applied to the vertical storage medium and the electromagnetic field copy master.

Abstract: Various systems and methods for accessing data via a variable polarity head assembly are disclosed herein. As one example, a method for accessing data is disclosed that includes receiving a data set, and sampling the data set using positive synchronization to create one data set and negative synchronization to create another data set. A respective sync mark is identified in each of the data sets, and the identified sync marks are compared. Based at least in part on the comparison of the sync marks, a polarity of the data set is identified. Based on the determined polarity of the data set, the data set may be delivered in a known polarity.

Abstract: Embodiments in accordance with the present invention suppress an adverse influence on a pattern of a magnetic disk due to its rotational jitter and write the pattern at more accurate timing. In accordance with one embodiment, a hard disk controller/microprocessing unit (HDC/MPU) controls a clock frequency of a data clock generation circuit so that a rotational jitter of the magnetic disk be compensated when writing and reading user data. The HDC/MPU expects a detection timing of next adjacent servo sector using an error between an actual detection timing and an expected detection timing of a servo sector which has already been detected. The HDC/MPU controls the clock frequency using the expected timing and writes and reads user data between current servo sector and next adjacent servo sector according to the clock signal.

Abstract: Embodiments of the present invention provide an approach in the time domain, instead of the frequency domain, for analyzing and correcting for radial propagation instability in servo-writing. In one embodiment, a system for controlling a read/write head of a disk drive to correct propagation errors during self-servo writing on a disk comprises a time-domain based controller to provide closed-loop feedback control to an actuator for moving the read/write head, the controller including a state observer. The controller is configured to measure read head position information of the read/write head on the disk; provide the measured read head position information to the state observer which produces feedback variables for feedback control of the read/write head, the feedback variables being weighted by feedback gains which have been determined a prior; and apply the weighted feedback variables to provide the closed-loop feedback control to the actuator for moving the read/write head.

Abstract: In a write-once type storage apparatus, a head having a recording element and a recording element is supported at the leading end of a rotary actuator, and information written once in a disk medium by the head is then reproduced. A write processing unit writes information sequentially from a track giving the largest yaw angle of the actuator in the recording track area of the disk medium to a track giving a yaw angle of 0°. For example, the write processing unit writes information sequentially from the outermost track of the disk medium toward a track giving a yaw angle of 0°, and then, writes information sequentially from the innermost track to a track giving a yaw angle of 0°. A read processing unit reads out information write-once-written in the disk medium from a track of a larger yaw angle toward a track of a smaller yaw angle.

Abstract: There is provided an information recording/reproduction apparatus, a head levitation height control method, and a head levitation control circuit capable of adequately controlling a head levitation height. An information recording/reproduction apparatus having a head 41 that performs recording or reproduction of information on/from a recording medium, comprises: a drive section 43a that changes the levitation height of the head 41 relative to the recording medium based on a first drive method; a drive section 43b that changes the levitation height of the head 41 relative to the recording medium based on a second drive method different from the first drive method; a levitation height measurement section that measures the levitation height of the head 41; and a controller that controls the drive sections 43a and 43b based on the head levitation height measured by the levitation height measurement section.

Abstract: In an embodiment of the present invention, a Hard Disk Controller Microprocessing Unit (HDC/MPU) supplies, prior to the unloading process, different currents to a VCM, with an actuator positioned in place and kept at a standstill. The HDC/MPU determines a correction factor from VCM speeds vmeas, each of which is detected at each of VCM currents Ivcm. If the determined correction factor falls outside a reference limit, the HDC/MPU determines a new circuit parameter for a VCM speed detection circuit. Further, the HDC/MPU calculates a new correction factor appropriate to the circuit parameter. The HDC/MPU and the VCM speed detection circuit control the speed of the VCM in the unloading process using the new circuit parameter and the new correction factor.