摘要:
A movable filter device comprises a rotary plate for holding an optical filter, a holding plate for holding the rotary plate rotatably at a pivot point, stopper pins, and a torsion coil spring. The torsion coil spring has one end coupled to the holding plate and the other end coupled to the rotary plate, and generates a force for extending both ends thereof. The force generated by the torsion coil spring prevents the rotary plate from stopping at positions other than those defined by the stopper pins. The rotary plate has slender portions of low rigidity for absorbing the impact of collision between the rotary plate and stopper pins.
摘要:
This invention provides an optical head apparatus in which a grating coupler (8), which is formed on a circular region which has a center on an axis (18) and has a periodical structure with dents and projections in a configuration of concentric circles or spirals around the axis (18), input-couples laser light (7) emitted from a semiconductor laser (5) and turns it into waveguided light (16B) which transmits in a waveguiding layer (15B). The waveguided light (16B) is converted, in a region where the waveguiding layer (15B) and a waveguiding layer (15A) overlap each other, to waveguided light (16A) which transmits in the waveguiding layer (15A). By a grating coupler (9), formed on a ring-shaped area which is located around the axis (18), which has a periodic structure with dents and projections of a configuration of concentric circles or spirals around the axis (18), the waveguided light (16A) is radiated and focused onto points (FA), (FB) and (FC) which are located on the axis (18). Light reflected from a reflecting surface (19) is input-coupled by the grating coupler (9) and is converted to waveguided light (21) which transmits through the waveguiding layer (15A) toward the center. The waveguided light (21) is radiated at the innermost edge of the waveguiding layer (15A) and the amount of radiated light is detected by a light detector (10) to obtained control signal and playback signals.
摘要:
An optical head arranged in such a manner that light emitted from a semiconductor laser (8) is inputted and coupled in a waveguide layer (3C) by a grating coupler (4C) having a concentric or spiral structure formed by concavities and convexities so as to convert light into waveguide light (12C) passing toward to outer periphery in the layer, the waveguide light (12C) is shifted at the outermost peripheral portion of the waveguide layer (3C) to a waveguide layer (3B) so as to convert the waveguide light (12C) into waveguide light (12B), the waveguide light (12B) is radiated by a grating coupler (4B) having a concentric or spiral periodical structure, the concentrically polarized (or radially polarized) light (13) is converted into linearly polarized light (14) by a polarizing element (10B) so as to be converged on the reflection surface (16) of the optical disc, light reflected from the reflection surface (16) is again converted into concentrically polarized (or radially polarized) light (17A) and (17B) by the polarizing element (10B) so as to be inputted and coupled in waveguide layers (3A) and (3B) by a grating coupler (4A) and the grating coupler (4B), and then to be turned into waveguide light (18A) and (18B) each of which passes through the layer, and the waveguide light (18A) and (18B) is radiated at the end portions of the waveguide layers (3A) and (3B) so as to be respectively received by photo detectors (6A) and (6B) so that a control signal and a reproduction signal are obtained.
摘要:
The voltage signal applied between a conductive thin film (2) and a transparent conductive thin film (6) changes the aligning direction of a liquid crystal layer (5) near the surface of a waveguide layer (4) so that the refractive index of the liquid crystal (5) for waveguide light (8) is changed thereby to change the equivalent refractive index for the waveguide light (8), and thus the diffraction angle of the radiated light (9) from the waveguide layer (4) including the cyclic structure (3G) formed therein is also changed to deflect the radiated light. If the waveguide light (8) is propagated in the direction perpendicular to the longitudinal direction of the arrangement of the cyclic structure (3G), which is arranged in the form of a concentric circle, and the radiated light (9) from the waveguide layer (4) is focused at a focusing point outside the waveguide layer (4), the deflection of the radiated light (9), which is caused by applying a voltage signal between the conductive thin film (2) and the transparent conductive thin film (6), produces a displacement of the focusing point. In particular, if the conductive thin film (2) or the transparent conductive thin film (6) is divided into a large number of sections and voltage signals are individually applied to such sections, the focusing point (F) can be displaced to any optional point.