Abstract: A varifocal lens whose variable focal length can be controlled by, for example, an electric signal, and suitable for use in bar code readers, etc. A varifocal lens comprises a first pressure chamber defined between a glass substrate and a transparent elastic film. The transparent elastic film is faced to the surface of the planar glass substrate having parallel surfaces with a spacer incorporated therebetween to provide the first pressure chamber. A pump is provided adjacent to the first pressure chamber via a communicating path for charging an operating liquid to the first pressure chamber from a second pressure chamber of the pump by electrically deforming the transparent elastic film to form a lens having a variable focal length. The transparent elastic film has a film thickness distribution as such to provide a spherical plane in the central portion thereof and a third order curved surface in the periphery thereof.

Abstract: An optical data reader including a device for producing a light beam, and a device for changing a condensing position of the light beams before the light beam is reflected from a target such as a bar code. The device for changing the condensing position is either a variable focus lens or mirror, each adapted to change the curvature of the surface of the lens or mirror in order to move the condensing position cyclically and continuously. The variable focus mirror changes the shape of its reflecting surface in response to electrical signals from a driving circuit. Excess pressure within the mirror caused by the mirror surface being attracted inwards is expelled through intake/outlet ports formed in the drive electrode. The variable focus lens alters the focal length of the lens each time the curvature of the surface thereof is changed. Preferably, the curvature of the lens surface is changed by increasing fluid pressure within the lens, while the curvature of the variable focus mirror is electrically driven.

Abstract: A micro machining apparatus forms a high-aspect structure having an optional depth in a workpiece at low cost. The apparatus applies high-frequency electric power to the workpiece and a machining electrode, to form a plasma zone in the vicinity of the leading end of the machining electrode. The apparatus guides a reactive gas into the plasma zone to activate the gas. The activated gas is adsorbed by the surface of the workpiece that faces the leading end of the machining electrode. The adsorbed gas reacts with the material of the workpiece and locally etches off the surface of the workpiece. A feed mechanism of the apparatus feeds the machining electrode toward the workpiece according to the progress of the etching, thereby forming a trench in the workpiece.

Abstract: An electrode for electrical discharge machining. This spark-machining electrode improves the accuracy at which the workpiece is machined by electrical discharge machining. The electrode can dispense with a mechanism which scans the spark-machining electrode or the workpiece. A plurality of needlelike electrodes are formed on the surface of the spark-machining electrode. The needlelike electrodes are so arranged that they are present in craters created by their respective adjacent needlelike electrodes. The plural electrodes form a group. The shape of the surface of this group is formed according to the desired shape to be formed in the workpiece. Art electric discharge occurs mainly at the tips of the needlelike electrodes and so the capacitance is smaller than the capacitance of the prior art flat-plate electrode. Also, the energy of a single electric discharge can be reduced.

Abstract: A method for producing PLZT generally expressed as (Pb.sub.1-x La.sub.x) (Zr.sub.1-y Ti.sub.y).sub.1-x/4 O.sub.3 (0<x.ltoreq.0.3, 0.ltoreq.y.ltoreq.1.0) comprises the steps of forming a coprecipitated body by reacting solution containing at least one of Pb, La and Ti with a zirconium-containing solution and a precipitation-forming solution, or (a) forming a solution containing at least one of Pb, La and Ti forming PLZT generally expressed as (Pb.sub.1-x La.sub.x) (Zr.sub.1-y Ti.sub.y).sub.1-x/4 O.sub.3 (0<x.ltoreq.0.3, 0.ltoreq.y.ltoreq.1.0) and a zirconium-containing solution and carrying out a hydrolysis reaction to produce a sol body, (b) drying and then presintering the coprecipitated body at a temperature of from 700.degree. to 1300.degree. C. to form a modified zirconia powder, (c) mixing the presintered body with a compound having a remaining component composition of a required PLZT composition, (d) presintering the mixture at a temperature of from 500.degree. to 1000.degree. C.