Abstract: A miniature lens system that corrects for imaging and chromatic aberrations, the lens system being fabricated from primarily commercially-available components. A first element at the input to a lens housing is an aperture stop. A second optical element is a refractive element with a diffractive element closely coupled to, or formed a part of, the rear surface of the refractive element. Spaced closely to the diffractive element is a baffle to limit the area of the image, and this is closely followed by a second refractive lens element to provide the final correction. The image, corrected for aberrations exits the last lens element to impinge upon a detector plane were is positioned any desired detector array. The diffractive element is fabricated according to an equation that includes, as variables, the design wavelength, the index of refraction and the radius from an optical axis of the lens system components.

Abstract: Methods of etching optical elements in association with photosensitive elements are described. In some of the arrangements, the optical elements are formed integrally with a substrate containing the photosensitive elements. In other arrangements, an optical element is mounted to a package, or the like, containing the substrate and photosensitive elements. In other arrangements, two or more optical elements are employed, including conventional refractive elements, refractive focusing elements, and refractive beam splitting elements. Utility as solid state image sensors is discussed. Utility for monochromatic and color imaging is discussed.

Abstract: A camera comprising various arrangements for employing optical elements in association with photosensitive elements are described. In some of the arrangements, the optical elements are formed integrally with a substrate containing the photosensitive elements. In other arrangements, an optical element is mounted to a package, or the like, containing the substrate and photosensitive elements. In other arrangements, two or more optical elements are employed, including conventional refractive elements, refractive focusing elements, and refractive beam splitting elements. Utility as solid state image sensors is discussed. Utility for monochromatic and color imaging is discussed. Various devices based on such camera arrangements and methods of making same are discussed.

Abstract: Optical machining of a workpiece with coherent light scanning a plate with a plurality of subaperture subapertures is disclosed. Each of the subapertures creates a working image which when scanned with a coherent wave front of the design frequency forms in three dimensional space the working image. The working image when registered to a workpiece effect processing of the workpiece, usually ablating an aperture such as a blind via of small dimension. Improved techniques of dimensioning and fabricating the subaperture, creating amplitude modulation with the phase plate, and finally controlling amplitude with optical features close to the limit of producible optical elements is disclosed. The apparatus for the process, the process and the plate for utilization in the process are set forth.

Abstract: A chromatic aberration correcting element that is a simple lens having at least one aspheric surface the radius of curvature of which increases from the optical axis toward the periphery, at least either one of the surfaces being formed as a diffraction lens surface that consists of annular segments in steps that are shifted discretely in a direction in which the lens thickness increases as a function of the distance from the optical axis. Also, a chromatic aberration correcting device having annular segments formed in steps on either a light entrance face or a light exit face or both, the annular segments being composed of planes perpendicular to and concentric with the optical axis.

Abstract: Diffractive lenses having gradial zones (62, 70, 78, 90, 98, 106, 114) are formed by separately, sequentially spin casting and polymerizing successive radial zones of the lens to produce optical phase differences of 2.pi. between adjacent gradial zones. Diffractive lenses may be molded in plano-plano(60), plano-concave (68) and plano-convex (76) geometries and also may be combined with conventional plano-plano (84), convex-convex (92), plano-concave (100) and plano-convex (108) refractive lenses.

Abstract: The optical system of the invention includes a phase type Fresnel zone plate 5. The zone plate 5 includes thereon a central zone C located around the optical axis, through which light flux 2 emanating from an object and having a relatively small divergence angle passes, and a peripheral zone P located on the outside thereof. The central and peripheral zones C and P have given Fresnel pitches and blazing angles, so that the peripheral zone P can make use of diffraction higher in order than that used by the central zone C to obtain the desired refractive power. Although the minimum pitch of the phase type Fresnel plate zone is thus relatively larger in the peripheral zone P, the optical system is not only satisfactory in terms of the effect on correction of chromatic aberration and refractive power but ensures a good image surface contrast as well.

Abstract: A projection lens system with a high resolving power and a wide exposure area which is effectively corrected for various aberrations including chromatic aberration and which is compact and has minimal production problems in a case where there is a limitation on vitreous materials usable as a lens material. The projection lens system (10) includes a plurality of lenses, at least one of which is a diffractive optical element (DOE) (11). The DOE (11) has a pitch arrangement in which it has a positive power in a paraxial region thereof, and wherein the positive power continuously changes to a less positive power, and then to a negative power as the distance from the optical axis of the DOE (11) increases toward the periphery thereof. Since the DOE (11) produces large aberrations which are opposite in sign to aberrations produced in the refracting system, it is possible to effectively correct various aberrations in the projection lens system (10) and also axial chromatic aberration.

Abstract: A method of manufacturing a diffractive surface comprising: rotating a surface to be cut at a rate W>1,500 RPM; translating a cutting tip at low speed V where V<1.2 mm/minute; and cutting the surface with the cutting tip.

Abstract: A polychromatic diffractive lens is usable with broadband or multi-spectral illumination to bring a plurality of spectral components of the illumination to a common focus in space. The lens has a Fresnel zone structure of zones and a profile which provides a phase jump delay at each zone boundary to the illumination of at least one of the spectral components which is greater than one period (wave) of that wavelength, and more particularly, a multiple of 2.pi.p, where p is an integer greater than or equal to two. The parameter p and the width of the zones are selected so that the spectral components are directed, and if desired directed so as to be brought to the common focus with high diffraction efficiency in distinct diffractive orders, the lens thereby being a multi-order diffractive (MOD) lens.

Abstract: An optical device having a variable index of refraction across its surface includes a light transmissive material with a plurality of regions in the light transmissive material. Each region has an index of refraction which is different from the remainder of the material. The regions may be arranged in the surface of the material such that the density of the regions on the surface varies across the surface. Each region may be a bore, including a hole that extends through the light transmissive material. Variations in the density of the regions or bores as well as the depth and shape of the bores may be utilized to create variations of the refractive index within the light transmissive material.

Abstract: In a stepped lens with a Fresnel surface structure produced by lithography and a process for fabricating same, the high potential exposure speed of high-speed electron-beam exposure systems which work with variable rectangular beam cross sections is converted in such a way that stepped Fresnel type lenses can be fabricated with high efficiency and, in so doing, the required amounts of data is reduced. According to the invention, radiation dose distributions which correspond to cylindrical lenses are exposed one upon the other, at least one of the radiation dose distributions corresponding to a Fresnel type cylindrical lens.Lens structures with any desired lens curvature, from radially spherical to elliptical, can be efficiently produced by lithography by the disclosed process.

Abstract: A diffractive optical device includes a substrate for allowing transmission therethrough of light to be diffracted; and a grating section located on the substrate and including a plurality of grating elements each having multiple discrete phase levels. The plurality of grating elements are arranged at different grating periods in different areas of a surface of the substrate and have the phase levels in different numbers in accordance with the grating period.

Abstract: The invention relates to a reduction projection lens system of high resolution which enables chromatic aberration to be corrected, and can be improved in terms of transmittance by making the total thickness of the vitreous material forming said lens system. This reduction projection lens system includes refractive and diffractive optical elements and uses as the light source a spectral light source having a center wavelength of up to 300 nm and a wavelength spectral bandwidth of .+-.0.5 pm to .+-.200 pm such as an ArF or KrF excimer laser. The refractive optical element includes at least one aspheric surface, and the refractive and diffractive optical elements are made of the same vitreous material, e.g., SiO.sub.2. conditions, 0.02<.vertline.d/D.vertline.<0.17 and 0.01<.vertline.h/H.vertline.<0.

Abstract: A hybrid refractive and diffractive achromatic lens suited for single-use or inexpensive single-lens cameras operating in visible spectral range. The lens comprises a body of optically transmissive material having an index of refraction at a wavelength approximately at the center of said range of at least 1.45. The lens body having a first and second surface on opposite sides thereof, at least one of said surfaces being curved to provide a refractive portion having power and introduces chromatic aberration, the lens having a diffractive portion having power which substantially achromatizes the lens for the chromatic aberration of the refraction portion over about 440 nm to about 650 nm range.

Abstract: A camera comprising various arrangements for employing optical elements in association with photosensitive elements are described. In some of the arrangements, the optical elements are formed integrally with a substrate containing the photosensitive elements. In other arrangements, an optical element is mounted to a package, or the like, containing the substrate and photosensitive elements. In other arrangements, two or more optical elements are employed, including conventional refractive elements, refractive focusing elements, and refractive beam splitting elements. Utility as solid state image sensors is discussed. Utility for monochromatic and color imaging is discussed. Various devices based on such camera arrangements and methods of making same are discussed.

Abstract: Dispersive microlens apparatus and methods are used in one mode for detecting multiple, different wavelengths from a bandwidth of wavelengths (existing within an image plane blur spot) and are used in another mode for combining a plurality of different, emitted wavelengths into a bandwave of wavelengths (at a blur spot in an image plane).

Abstract: An infrared continuous zoom telescope or afocal lens system using a diffractive surface for color correction. The lens system comprises an objective lens, an eyepiece lens, a plurality of lenses disposed between the objective lens and the eyepiece lens to provide the zoom function and a diffractive pattern disposed at a surface, preferably the interior surface and preferably integral therewith, of the objective lens to provide color correction at a predetermined wavelength of light passing through the objective lens. All of the lenses are preferably germanium. The diffractive pattern comprises a plurality of spaced ring-shaped steps, each ring concentric with the center of the objective lens and each step having a height equal to the predetermined wavelength for which the lens system is designed. The plurality of ring-shaped steps are formed in accordance with a known formula.

Abstract: Diffractive lenses having gradial zones (62, 70, 78, 90, 98, 106, 114) are formed by separately, sequentially spin casting and polymerizing successive radial zones of the lens to produce optical phase differences of 2.pi. between adjacent gradial zones. Diffractive lenses may be molded in plano-plano (60), plano-concave (68) and planoconvex (76) geometries and also may be combined with conventional plano-plano (84), convex-convex (92), plano-concave (100) and plano-convex (108) refractive lenses.

Abstract: A zone plate focusing radiation comprises a plurality of surface portions (20a, 20b, 20c, 20d, 30) corresponding to zones of the zone plate. The surface portions are positioned in a plurality P of parallel planes such that each surface portion diffracts radiation out of phase with respect to adjacent surface portions such that radiation diffracted by the surface portion constructively interferes at a focus of the zone plate. The p.sup.th plane is dielectrically spaced from the first plane by n.lambda., where .lambda. is the wavelength of the radiation and n is an integer.

Abstract: A method and apparatus for splitting, scanning and receiving a beam of light is disclosed. Binary optic array components are used to split, in an angular manner, an input beam into multiple beams, traveling in different directions. Miniaturized array element BOCs arranged in "n" different groups are used, wherein n is dependent upon the number of split beams needed or desired. An offset is introduced between the optical axis of each of the corresponding pair of miniaturized BOCs. By varying the offset over time, the resultant beam(s) can be scanned in one, two or three dimensions. Piezo-electric drivers controlled by a processor may be used to move the array in order to vary the offset. The device may also include a collection area to collect the returned scanned beams by using an array of optic components integrated with the scanner. The collected beams are then focused onto detectors.

Abstract: An optical scanning system uses a stationary binary diffractive optical element and a rotating binary diffractive element to focus and scan a beam along the scan line.

Abstract: Eyepiece optical systems having arrangements of surfaces where light is refracted or diffracted provide eyepieces with fewer elements and more compact designs than comparable, conventional eyepiece designs. These eyepiece optical systems have three elements each with positive focussing power, and provide a wide field-of-view of about 70.degree. and an eye relief of approximately 80% of the total focal length of the eyepiece. One embodiment has (from the eye side) a refracting, meniscus, positive element with a surface concave toward the eye, a bi-convex element having a refracting convex surface and a second refracting convex surface, and a refractive/diffractive doublet element with a refracting convex surface and diffracting surface (each element being of positive power).

Abstract: Chromatic dispersion between first and second wavelengths of light is corrected by a lens/zone plate combination. The zone plate is adapted both to send most of the first wavelength light into its zeroth order and to send most of the second wavelength light into its first order and to change the focal length of the second wavelength light to coincide with the focal length of the first wavelength light. A preferred embodiment includes a zinc/selinide sulfide lens having a zone plate etched onto one of its surfaces. The zone plate has a multi-step phase profile including four phase levels. The lens/zone plate combination is particularly adapted for use with CO.sub.2 and HeNe lasers to bring their focal lengths into coincidence.

Abstract: A virtual image display optical system. The system includes an image source, a combiner, and a relay group. The relay group is a catatrioptic relay group that includes a reflective optical element, and a refractive lens group that includes at least one doublet and a diffractive lens. For some applications, the catatrioptric relay group may be replaced by a hybrid refractive-diffractive relay group, thus eliminating the reflective element. The diffractive optical element of the hybrid optical element is encoded on one side of a lens. The hybrid optical element forms a refractive/diffractive achromat to provide for primary chromatic aberration correction. The refractive lens group is also an achromat to provide for chromatic aberration correction. Power distribution between the hybrid optical element and the refractive lens group is such that secondary chromatic aberration of the refractive lens group is balanced out by the secondary chromatic aberration of the hybrid optical element.

Abstract: An optical mask including a 2.pi.n phase shifter pattern, a .pi.(2n+1) phase shifter pattern, an intermediate phase shifter pattern which shifts the phase of an incident light by an angle between 2.pi.n and .pi.(2n+1), and a reversed intermediate phase shifter pattern which shifts the phase of an incident light by an angle being reversed by .pi. for the phase shift angle of the intermediate phase shifter pattern. The intermediate phase shifter patterns are formed in the vicinity of the reversed intermediate phase shifter patterns having light shielding films in between.

Abstract: An aperture device for use in an optical apparatus has a plurality of aperture blades which cooperate in collectively defining an aperture of a desired size. The inner edge of at least one of such blades defining one side of the aperture is uneven over at least part of the length of the inner edge. The spacing between adjacent relatively high portions and relatively low portions, as well as the depth, is smaller than the exposed length of the inner edge of each aperture blade when the aperture device has been operated to the minimum aperture size. Preferably, the spacing between adjacent crests or between adjacent high portions and low portions of the unevenness varies in a non-periodic manner.

Abstract: A method for producing a phase hologram using e-beam lithography provides n-ary levels of phase and amplitude by first producing an amplitude hologram on a transparent substrate by e-beam exposure of a resist over a film of metal by exposing n.ltoreq.m.times.m spots of an array of spots for each pixel, where the spots are randomly selected in proportion to the amplitude assigned to each pixel, and then after developing and etching the metal film producing a phase hologram by e-beam lithography using a low contrast resist, such as PMMA, and n-ary levels of low doses less than approximately 200 .mu.C/cm.sup.2 and preferably in the range of 20-200 .mu.C/cm.sup.2, and aggressive development using pure acetone for an empirically determined time (about 6 sec.) controlled to within 1/10 sec. to produce partial development of each pixel in proportion to the n-ary level of dose assigned to it.

Abstract: The current limits of resolution of multi-element optical systems are exceeded by reducing the number of elements while introducing at the critical aperture a blazed transmission grating having grating rings of low bending power defined by multiple plateaus. By illuminating the optical train with monochromatic light that constitutes a multiplicity of distributed sources having a substantial temporal coherence but spatial incoherence and by varying the slopes and widths of the grating rings, local phase delays are introduced that adjust aberrations in the optical system, providing an aligned composite wavefront. The system and method may be used for presenting an image, as for a wafer stepper, or for viewing an image, as in a microscope.

Abstract: A non-mechanical beam deflector forms and scans a beam of millimeter wave (MMW) radiation at a rapid rate. The beam deflector includes a semiconductor body in which a spatially varying density of charge carriers is selectively injected. The injected charge carriers--electrons and/or holes--alter the dielectric constant of the semiconductor body locally and thereby attenuate and reflect incident MMW radiation. The portions of the semiconductor body that do not have carriers injected therein allow the incident MMW radiation to be transmitted. The semiconductor body, modified with a spatially varying density of charge carriers, diffracts the radiation which passes through it into a beam. The beam may be scanned across space through selective control of the injected charge carriers. The diffractive conditions can be rapidly re-configured.

Abstract: A method of fitting rigid gas permeable contact lenses comprising the steps of:providing a set of lenses of differing BCOR values, but the same optical corrective power;fitting a patient with a lens to determine an acceptable BCOR value for the patient;determining the corrective prescription for that patient; andsupplying the patient with a lens having an acceptable BCOR value and the correct prescription.The lens supplied is manufactured in the same geometry and fitting characteristics as the lens from the set used in fitting and adjusted to the correct prescription power from the fixed power by diffractive means.

Abstract: A diffractive/refractive hybrid lens for use in an optical data storage system as an objective is provided by a convex-plano singlet having a refractive element defined by plano-convex surfaces and a diffractive element defined by a Fresnel zone-like pattern on the plano surface which together provide the total power of the lens. The refractive lens is made of a high index, high dispersion glass so that the curvature and thickness of the refractive lens is minimized while providing a large numerical aperture (at least 0.45) at the expense of increased longitudinal chromatic aberration, which are compensated by the diffractive element and without the need for one or more additional curved surfaces as in low index biaspheric glass objective lenses for chromatic and mono-chromatic aberration reduction, which increases the thickness and curvatures of the lens.

Abstract: An optical synchronization system uses a rotating disc with alternating binary diffractive optical elements for a synchronization signal for a pixel clock.

Abstract: An optical scanning system uses a double pass of a light beam through two rotating binary diffractive optical elements on a disc to focus a scan beam at a scan line and to scan the beam along the scan line which doubles the scan angle of the beam.

Abstract: The present invention involves a corrective optical lens construction and process for its manufacture. The lens construction consists of a glass lens having a corrective layer consisting of a blazed grating of annuli whose angles are formed to correct aberrations in the glass lens. In a first embodiment, the corrective layer is formed on one convex surface of the lens. In a second embodiment, the corrective layer is formed on a second convex surface of the lens. Embodiments also describe alternative lens shapes and corrective layer construction. A method of manufacturing the lens is also disclosed in which the resin corrective layer is molded to the glass lens.

Abstract: An optical synchronization system uses a stationary binary diffractive optical element and a rotating disc with alternating scattering binary diffractive optical elements and transmissive elements to create a moire pattern for a synchronization signal for a pixel clock.

Abstract: A re-imaging optical system (10) has a ref lective objective (12) providing an intermediate image of the object being viewed and a relay (14) including refractive (32, 62) and diffractive (34, 72) optical elements. The system is capable of re-imaging the intermediate image onto an image plane (16) with the characteristic advantages of reflective and refractive systems while eliminating their deficiencies.

Abstract: A diffractive mirror has a plurality of diffractive zones at least one of which has an optical step having a height equal to j.lambda./2 and at least one of which has an optical step having a height equal to k.lambda./2 where .lambda. is a design wavelength of the mirror and j and k are unequal nonzero integers. Alternatively stated at least one of the optical steps induces a relative phase shift of 2j.pi. at the image point between two light rays emerging from a point source at the object point and striking the lens immediately on opposite sides of the step and at least one of the steps induces a relative phase shift of 2k.pi. at the image point between two light rays emerging from a point source at the object point and striking the lens immediately on opposite sides of that step.

Abstract: A method for constructing a Nipkow disk using a zone plate disk, comprises the steps of constructing a zone plate disk, including the substep of disposing a plurality of focusing means a long a disk, wherein the plurality of focusing means have a common focal distance; placing a photographic plate at the focal distance of the plurality of focusing means; illuminating the plurality of focusing means with a light source such that the illumination is passed through the plurality of focusing means and focused onto the photographic plate thereby creating an image of a plurality of points of focused illumination; and capturing the image created on the photographic plate and using it to construct the Nipkow disk.

Abstract: A process is provided for fabricating multi-discrete-phase binary Fresnel acoustic and optical lenses through the use of standard microelectronic fabrication techniques, thereby enabling such lenses to be produced repeatedly and economically to exacting design specifications.

Abstract: This invention relates to the fabrication of lenses which can focus a light beam to a spot size which is smaller than that allowed by diffraction theory. A composite lens function is constructed using a strong centered lens function and several additional lens functions having different weights, different separation distances from the center, and different phases. The focused spot consists of the vector sum of these differently weighted electric fields from the separate lens functions. By varying the separation distances, the weights, and the phases of the additional lens functions, the vector sum of the electric fields from the lens functions produces a focused spot whose width is less than the diffracted limited spot size. Such composite lens functions can be produced, for example, using diffractive optics techniques or by programming the lens function onto a spatial light modulator.

Abstract: A reticle and a method of fabricating the samer for projecting a fine pattern on an object surface comprises: a. transparent substrate; a first type phase-shifter selectively patterned and deposited on the substrate producing a phase difference between the light passing therethrough and the light passing through the other areas without phase-shifter; and a second type phase-shifter selectively patterned and forming a groove in the substrate producing a phase difference between the light passing therethrough and the light passing through the other areas without phase-shifter. The reticle may include a patterned shield layer which interrupts transmission of light, and the phase difference of the first and second type phase-shifters is many times selected substantially equal to a half wavelength of light. Another type of a reticle comprises: a transparent substrate; a phase-shifter of a first groove; and another phase-shifter of a second deeper groove formed in the first groove.

Abstract: A procedure for supplying a mirror (22), such as the mirror of an astronomical telescope (60), with holographic optical elements (38), suitable for use with an active mirror alignment system such as a Hartman optical mirror alignment system, is accomplished by constructing each holographic optical element as a separate unitary structure of a transparent substrate (56) with zone plate features. The zone plate features include the channels (64) and ridges (66) of a fragmentary portion of a zone plate etched into a face (58) of the substrate. The substrate is mounted to the mirror by placing the etched face of the holographic optical element in contact with the reflecting surface (68) of the mirror. An adhesive (70) may be applied around the perimeter of the substrate to secure the substrate in its position upon the mirror.

Abstract: A zoom lens (10) has a first lens group (12), a second lens group (14) and a third lens group (16). The first lens group relays an outside scene to an intermediate plane. The second lens group varies magnification of the relayed image from the first lens group. Also, the second lens group includes at least one diffractive optical element. The third lens group compensates for focus shift and focuses the wavefront onto the viewing plane.

Abstract: Method and apparatus for creating discrete phase optical elements. An arbitrary phase structure is represented by color encoding to produce a color encoded mask. Thereafter, a photo-sensitive substrate is exposed to broad spectrum light transmitted through or reflected from the mask to create the discrete phase structure in the substrate. In preferred embodiments, the exposed substrate is developed and bleached (if necessary) to remove pigmentation to produce highly efficient multiple level phase structures for optical applications. The color encoded mask is produced by a computer-driven color printer resulting in very fast turnaround times.

Abstract: A lens composed of a single material and having at least one refractive surface on one face and a kinoform on the other face. The purely refractive between the surfaces varies dimensionally and in refractive index in response to temperature changes and thereby changes a characteristic, such as back focal length, of the lens while the kinoform varies differently in response to the same temperature changes. The kinoform power is sufficient to vary the temperature induced characteristic changes of the lens in an opposing sense at a given wavelength and in an amount sufficient to athermalize the optical device. In one embodiment the kinoform power compensates for the combined temperature-induced effects upon the refractive portion and any mount that supports the lens.

Abstract: An optical synchronization system uses a stationary binary diffractive optical element and a rotating disc with alternating binary diffractive optical elements and blocking elements to create a moire pattern of a synchronization signal for a pixel clock.

Abstract: A broadband diffractive lens or imaging element produces a sharp focus and/or a high resolution image with broad bandwidth illuminating radiation. The diffractive lens is sectored or segmented into regions, each of which focuses or images a distinct narrowband of radiation but all of which have a common focal length. Alternatively, a serial stack of minus filters, each with a diffraction pattern which focuses or images a distinct narrowband of radiation but all of which have a common focal length, is used. The two approaches can be combined. Multifocal broadband diffractive elements can also be formed. Thin film embodiments are described.

Abstract: A re-imaging optical system (36) is provided which utilizes a combination of refractive and diffractive optical elements. The system includes an objective lens group (38) for focusing an incoming beam of light to a first image plane. A relay lens group (40) refocuses the beam of light in a second image plane after it passes through the first image plane. The relay lens group (40) includes a diffractive optical element (48) for correcting aberrations introduced by the objective and relay lens groups. The diffractive optical element (48) eliminates a number of individual optical elements which would otherwise be required to correct aberrations, thereby reducing the total number of optical elements in the system. In the preferred embodiment, the diffractive optical element (48) comprises a binary optical element. The resulting system yields better image quality, better throughput, and a lighter, less bulky, re-imaging optical system (36).

Abstract: Apparatus for transforming a conventional beam of coherent light, having a Gaussian energy distribution and relatively high divergence, into a beam in which the energy distribution approximates a single, non-zero-order Bessel function and which therefore has much lower divergence. The apparatus comprises a zone plate having transmitting and reflecting zones defined by the pattern of light interference produced by the combination of a beam of coherent light with a Gaussian energy distribution and one having such a Bessel distribution. The interference pattern between the two beams is a concentric array of multiple annuli, and is preferably recorded as a hologram. The hologram is then used to form the transmitting and reflecting zones by photo-etching portions of a reflecting layer deposited on a plate made of a transmitting material. A Bessel beam, containing approximately 50% of the energy of the incident beam, is produced by passing a Gaussian beam through such a Bessel zone plate.