In an optical pickup, the focal position of the reflected light from the information bearing surface where information is to be reproduced and that of the reflected light from other information bearing surfaces are adjusted by an optical device such that the two reflected light components are separated optically.

A centrifuge microscope that includes: a rotary disk in which are provided a slit and a sample chamber; a light source for illumination; a projecting optical system; and an objective lens. The projecting optical system includes an imaging lens, a pair of reflecting mirrors, and a projecting lens which are constructed and arranged such that an erect image or an inverted image of the slit is projected on a sample contained in the sample chamber. During rotation of the rotary disk, the slit image and the sample sweep by each other in front of the objective lens, whereby the sample can be observed via the objective lens as a still image having better definition.

An optical beam in a scanning device is focused on an information layer of a multi-layer optical record carrier. A focus control circuit keeps the focal point of the beam on the information layer. When the focal point jumps to another information layer, the focus control circuit does not monitor the so-called central aperture signal in order not to depend on the presence of information in the information layers. During the jump the characteristics of the feedback loop of the focus control unit are modified to avoid instabilities in the movement of the focal point during the jump. When the focal point is captured on the designated information layer, the characteristics of the feedback loop are restored.

A near-field laser and detector apparatus and method wherein both writing and reading of optical media can be carried out using the same laser operating in a single mode for both read and write operations. The single operational mode can be utilized with both edge emitting and surface emitting laser configurations, and allows readout via rear facet output power variation or by voltage variation across the laser. A small aperture laser is operated during read and write operations at a bias current which is higher than the threshold currents associated with feedback from high and low reflectivity regions of an optical medium. The bias current and laser structure provide a relatively high, continuous output power from the front emission facet of the laser to facilitate writing, while providing substantial fluctuation or change in output power from the rear emission facet to facilitate readout.

A near field optical apparatus comprising a conductive sheet or plane having an aperture therein with the conductive plane including at least one protrusion which extends into the aperture. The location, structure and configuration of the protrusion or protrusions can be controlled to provide desired near field localization of optical power output associated with the aperture. Preferably, the location, structure and configuration of the protrusion are tailored to maximize near field localization at generally the center of the aperture. The aperture preferably has a perimeter dimension which is substantially resonant with the output wavelength of the light source, or is otherwise able to support a standing wave of significant amplitude. The apparatus may be embodied in a vertical cavity surface emitting layer or VCSEL having enhanced nearfield brightness by providing a conductive layer on the laser emission facet, with, a protrusion of the conductive layer extending into an aperture in the emission facet. The aperture in the emission facet preferably has dimensions smaller than the guide mode of the laser, and the aperture preferably defines different regions of reflectivity under the emission facet. The depth of the aperture can be etched to provide a particular target loss, and results in higher optical power extraction from the emission facet.