Showing papers on "Lens (optics) published in 1993"

Real time optical correlation system

Abstract: An optical correlation unit (10) for correlating the images of an inspection object and a reference object. The unit uses two phase modulating reflective spatial light modulators (12a, 12b). A first spatial light modulator (12a) receives electronic input in the form of image data representing the inspection object. It modulates incoming light (15) with this input and reflects the modulated output to a first Fourier transform lens (13). This lens provides the optical input to second spatial light modulator (12b), whose electronic input is transform data presenting the complex conjugate of the Fourier transform of the reference image. The electronic input modulates the optical input, resulting in the Fourier product of the two images, which is then transformed to provide correlation data.

Device for writing to and reading from optical storage media

Abstract: A system for writing to, and reading from, optical media. For writing, the media changes when subjected to high intensity modulated light representing an image, such that the image is recorded. A deformable micro-mirror device (DMD) receives electrical input representing the image to be recorded. A high intensity light source illuminates the DMD, which reflects modulated light to an imaging lens. The lens focusses the image onto the media. To record multiple images on the same media, various embodiments provide for scanning across the media. For reading, the media is illuminated with uniform low intensity light. The DMD provides this uniform light, which is transmitted through a pre-recorded media to an image capture device.

Ideal microlenses for laser to fiber coupling

Abstract: The design and fabrication of ideal microlenses for semiconductor laser to fiber coupling are reported. Properly coated for reflections, lenses of the new design can theoretically collect 100% of the radiated energy of a modal-symmetric laser source. The crucial feature is its hyperbolic shape. Microlenses fabricated directly on the end of the fiber by laser micromachining have demonstrated up to 90% coupling efficiency. This performance represents a major advance in microlens technology when compared to currently fabricated hemispherical microlenses which are at best 55% efficient. A theoretical comparison of the two lens shapes illuminates the advantages of the hyperbolic profile. The ability to couple all of the light from a semiconductor laser into a fiber has far-reaching implications for all optical communication systems. >

Optical scanning head with improved resolution

Abstract: The optical scanning head comprises two or more LEDs which are oriented to emit light at different angles so that a fan of light is created. A "dark room" encloses the LEDs, a lens assembly, and the spacing between the lens assembly and the detector, a linear CCD array. The portion of the dark room that extends between the lens assembly and the detector has a plurality of baffles formed therein to capture scattered light, preventing this scattered light from becoming noise at the detector. The lens assembly includes, along with a plurality of focusing lenses, a combination of a generally elliptical aperture, or "cat's eye, and a rectangular obscuration. The combination prevents the central lobe of the Airy disk generated by the incoming light from being transmitted to the detector. This results in the incoming information being carried in the outer lobes or rings, increasing the angular separation of the lines of the bar code. Waveshaping software is incorporated in the decoding processor to compensate for the limitations of the imaging system, which include convolution distortion and the resulting loss of image contrast. This software is used to determine the scan parameters including global threshold for the next scan. As an alternative to use of a global threshold, a sliding frame buffer is used to generate pseudo-pixel numbers to fill in the space between physical pixels in the detector, providing a greater number of effective pixels to obtain better resolution.

LED light standard for photo- and videomicroscopy

Abstract: The invention relates to a light calibration system consisting of a compact LED source with feedback control of intensity. The source is positioned in the focal plane of the microscope objective and produces flat-field illumination of up to 31 microwatts. The source can be easily used to determine the performance of microscope optics and camera response. It can also be used as a standard light source for calibration of experimental systems. Selectable light intensities are produced by controlling the LED input power via a feedback circuit consisting of a photodiode that detects output light intensity. Spectral coverage extends between 550 nm and 670 nm using green, yellow and red LEDS mounted side-by-side and which are individually selected. The LED chips are encapsulated in plastic diffusers which homogenize the light, and a flat field of illumination is obtained through a thin 1 mm diameter aperture positioned directly over each chip. Provision is made for insertion of Ronchi rulings over the aperture to enable measurements of contrast modulation in a uniform field. The light can be pulse-modulated to assess camera response times and the device can be synchronized with video frames. Narrow bandpass interference filters can be placed between the objective lens and the LED source to produce monochromatic light without affecting the spacing of controlled light intensities since emission spectra do not appreciably shift over the range of LED powers chosen in this design.

High-numerical-aperture lens system for optical storage

Abstract: We describe a new type of optical pickup for use in high-density optical storage systems. By changing a conventional pickup design to include a glass element between the objective and the disk, the transverse resolution of the system can be increased by as much as a factor of 1.5. This system is also less sensitive than conventional systems to variations in disk thickness and disk tilt. We demonstrate how the system has been used as a microscope to inspect an optical disk and describe possible design configurations for an optical pickup.

Frequency converted laser diode and lens system therefor

Abstract: A compact semiconductor laser light source providing short wavelength (ultraviolet, blue or green) coherent light by means of frequency doubling of red or infrared light from a high power diode heterostructure. The high power diode heterostructure is a MOPA device having a single mode laser oscillator followed by a multimode, preferably flared, optical power amplifier. A tunable configuration having an external rear reflector grating could also be used. A lens could be integrated with the MOPA to laterally collimate the light before it is emitted. Straight or curved, surface emitting gratings could also be incorporated. An astigmatism-correcting lens system having at least one cylindrical lens surface is disposed in the path of the output from the MOPA to provide a beam with substantially equal lateral and transverse beam width dimensions and beam divergence angles. A nonlinear optical crystal or waveguide is placed in the path of the astigmatism-free symmetrized beam to double the frequency of the light. Single pass or multipass configurations with reflectors could be used, as well as external resonator and segmented, periodically poled waveguide configurations.

Laser diode/lens assembly

Abstract: A laser diode/lens assembly wherein a lens (or multi-lens assembly) is immovably adhered to a housing of a laser diode package The laser diode package may be a metal can style package having a substantially transparent window portion through which laser radiation is emitted when a laser diode inside the housing is supplied with current The lens may be immovably fixed to an outer surface of this window so that a central axis of a beam of laser radiation emerging from the lens has a desired spatial relationship with a reference surface of the housing An adhesive such as an epoxy adhesive which is cured under exposure to ultraviolet radiation may be used to freeze the lens in place to the window when the lens is correctly positioned In accordance with some embodiments of the present invention, a lens is positioned in three dimensions (X, Y and Z) and then fixed in three dimensional space with respect to a laser diode housing Fixing the position of the lens in the Z dimension at a desired location allows the focal point of the laser diode/lens assembly to be set so as not to focus laser radiation on a window of a gas spectroscopy device

Variable-focus liquid-filled optical lens

Abstract: A variable-focus liquid-filled optical lens consists of a solid plate, a ring spacer, and an elastic film; a liquid fills this lens-shaped container. One varies the focus by changing the liquid volume in the lens. The lens shape calculated theoretically is a paraboloid. However, it is approximately a sphere near the central area. The deformation of the lens shape by gravity was also calculated with a simplified structure in which the lens was held vertically and found to be independent of the elastic properties of the film. The effect of gravity was found to be negligible when the pressure at the liquid pump was more than 30 times that induced in the liquid at the bottom of the lens by the gravity. The aberrations of the lens were calculated and observed to be negligibly small compared with the normal convex spherical single-glass lens. A liquid-filled lens was fabricated and experimentally evaluated.

Renticular lens, surface light source, and liquid crystal display apparatus

Abstract: A lenticular lens has a light transmitting substrate and a plurality of lens elements formed on the light transmitting substrate. The lens elements are defined in such a way that ridges thereof are aligned in parallel with each other, wherein 30°≦θ 10% ≦100° and R≦20%, where θ 10% is a diffusing angle range with respect to normal of the one surface in the case that when light is entered from the opposite surface and transmitted from the one surface, the intensity of the light transmitted is equal to or more than 10% of the intensity of the light transmitted in a peak direction of a main lobe; and R is the ratio of side lobes to main lobe. The intensity of side lobes which causes light loss and light stray can be remarkably reduced. Light can be equally and isotropically focused on in a predetermined diffusing angle range.

In vivo modification of refractive power of an intraocular lens implant

Abstract: A change is effected in the refractive power (spherical and astigmatical) of an intraocular implant of the type having a lens, either formed of a series of laminates of material, or having a lens that is coated with material, said material, when subject to laser energy providing for its expansion or contraction, and thereby varying the curvature of the lens, and hence, effecting an increase or decrease in its relative refractive index or power. The direction at which the laser energy is applied to the lens can effect the relative change in the refractive power of the lens. A modification provides haptics diametrically or concentrically extending from the optic lens, with a segment of material such as hydrogel or collagen at the juncture between the haptics and the lens, which when directionally exposed to laser energy, can cause an increase or decrease in the relative refractive power of the implanted lens.

Optical system for light emitting diodes

Abstract: The diode is incorporated in a fixed manner on the optical axis of a carrier lens. The carrier lens consists of a front portion with an outer transverse surface, formed concave towards the emitted light, and a longitudinal portion for incorporating he diode. The longitudinal portion has its outer longitudinal surface formed concave towards the diode. The concave transverse surface is surrounded by a further outer transverse system. The concave longitudinal surface is arranged to reflect the diode-emitted light rays towards the further outer transverse surface, which is arranged to transmit the light rays to the outside in a longitudinal direction.

Method and apparatus for determining an objects position, topography and for imaging

Abstract: Light is supplied via a optical fiber to a probe head. The light exiting the optical fiber is focused to a point by a lens. Reflected light from an object at or near the focal point is reflected back through the lens and then focused to the source optical fiber or a second optical fiber located next the source optical fiber. The return signal is then detected in a detector module. By noting the characteristics of the response curve as the object is moved back and forth relative to the probe head, the position of the object can be determined. By performing this procedure over several points, a detailed topography map can be created. Additionally, the probe head can be scanned at a constant distance from the surface to produce an image of the surface as the response signal varies according to the surface's reflectivity. The microprobe can be used, for example, to find the position of probe tips on a wafer prober, to determine the topography of the surface of the wafer, and to find the position of the wafer edge.

Object tracking method for automatic zooming and the apparatus therefor

Abstract: An object tracking apparatus for an automatic zoom lens control in a video camera includes a memory for storing data for zoom track lines showing the relationship between the distance variation of a zoom lens and the distance variation of a focus lens while the distance of an object is kept constant, a zoom encoder for producing a zoom position signal showing the zoom lens position, a microcomputer for detecting the variation amount of the zooming position, and a zoom motor for variably controlling the zoom lens position corresponding to the detected zoom speed. A corresponding method for automatic object tracking using a zoom lens is also described.

Solid-state imaging array including focusing elements

Abstract: A solid-state imaging device includes a semiconductor substrate in which an element part including a plurality of light responsive elements for generating charge carriers in response to incident light and a transfer part for transferring the charge carriers generated in each light responsive element are incorporated; a lens layer is disposed on the element part so that incident light is collected in the light responsive elements; and a light beam dispersion layer is disposed between the lens layer and the element part and includes two light transmissive layers having different refractive indices for dispersing light collected by the lens layer so that collected light entering respective light responsive elements is closer to a parallel beam than the incident light. By suppressing broadening of incident light in the semiconductor substrate at the light responsive elements, fewer charge carriers enter the CCD channel region and smear is reduced.

Single in-line optical package

Abstract: An optical packaging arrangement is disclosed which utilizes silicon technology and overmolding techniques to provide a single in-line package with completely passive alignment between the various optical components. The technique as disclosed is useful in the packaging of a single active optical device and associated electronics, a pair of optical devices and electronics (transceiver), or an array of any desired number of such components. Since the silicon may be processed to include etched alignment fiducials and metallized bond pad sites, solder bump self-alignment and silicon optical bench technology may be used to provide for alignment between the active device, coupling lens and associated optical fiber.

Glasses type display apparatus

Abstract: A glasses type head mounted display apparatus for seeing a virtual image through left and right lens systems provided with corresponding left and right display portions displaying left and right pictures, respectively. The display apparatus includes left and right slide mechanisms for moving the respectively left and right display portions on the main point axes of the lens systems and on segment lines through the central points of the left and right lens systems and focuses of the left and right lens systems so that the user sees through the left and right lens systems a virtual image synthesized with pictures of the left and right display portions.

Method and apparatus for creating an image by a pulsed laser beam inside a transparent material.

Abstract: A method of creating an image inside a transparent material with the aid of a pulsed laser beam involves use of a diffraction limited Q-switched laser, in particular, a solid-state single-mode TEM00 laser; sharp focusing of the laser beam to provide an adjustable microdestruction in the material being treated; and mutual displacement of the laser beam and the material being treated after each laser shot to a next point of the image being reproduced. The microdestruction induced in the material at a pre-set point is adjustable in size by varying the actual aperture of the focusing lens and laser radiation power simultaneously. A device for carrying out said method comprises a laser 1, a defocusing lens 2 having a variable focal length, a focusing lens 4 capable of performing controlled motion along the laser beam 3 with the aid of an actuator 5, a drive 7 moving a specimen 6 made of a transparent material in a plane perpendicular to the laser beam 3, and a computer 8 guiding the process of specimen 6 treatment.

Optical system for virtual reality helmet

Abstract: The present invention provides an optical system for a virtual reality head mounted display with improved image quality, enlarged field of view, and enhanced adjustability. In one embodiment, the optical system comprises a housing coupled to the frame of the head mounted display, a pair of displays mounted to the housing each defining a visual plane, and first and second lenses mounted between each of the displays and the user's eyes. The lenses are mounted to the housing such that each lens is disposed at an angle of between 1° and 15° relative to the visual plane. The lenses are also mounted such that the interoptic distance between the lenses may be adjusted. The optical system also has a unique lens construction including a standard Fresnel lens mounted in parallel to a low-diffraction Fresnel lens, resulting in substantially reduced diffractive interference.

Long-wave optics

Abstract: The basis of the near-complete analytical methodology that now exists for the design of long-wave optical systems is set out. The Gaussian beam-mode treatment of free-space propagation is extended to cover the transformations produced by conic-section reflectors or lenses, and both the propagation steps and the lens transformations are incorporated into a matrix formulation readily applicable to networks of such reflectors or lenses. In the process the theorems of Fourier optics are demonstrated and the vectorial properties of the beam-fields are kept explicit. It is shown how recent formulations of partial coherence have made it possible to include partially coherent beams in the same methodology. For the design of high-performance systems, the inclusion of higher-order mode dispersion must be fully understood, the vector properties must be recoverable, and the paraxiality on which the methodology rests must be critically assessed. The authors emphasize these aspects and present a single systematic formulation embracing all the elements. >

Optical fiber illumination device

Abstract: An optical fiber illumination device is disclosed. The optical fiber illumination device includes at least one optical fiber cable, one or more light sources for introducing light into the optical fiber cable, a lens through which light from each light source passes prior to entering the optical fiber cable for producing a colored light, electrical circuitry for energizing the light source, and a housing for containing the circuitry and the light source. A first light source is energized by a first power source. Light emitted from the first light source passes through a first lens which possesses a desire filtering characteristic. Upon application of the second power source, a first control device disable the first light source. Moreover, the second power source may energize a second light source which passes through a second lens having a filtering characteristic distinct from that of the first lens. Upon application of a third power source, a second control device disables the first control device.

Optical illumination system and projection display apparatus using the same

Abstract: An optical illumination system includes a radiation source, a condensor, a first lens array including a plurality of first lenses, and a second lens array including a plurality of second lenses. The first lens array converges partial luminous fluxes, the number of which is the same as the number of first lenses, onto the second lenses paired with the first lenses. The second lens array transmits each of the partial luminous fluxes to an object region to be illuminated in such a manner that the partial luminous fluxes are superimposed on each other at the object region. Configurations of the apertures of the second lenses are different from each other and the second lenses are arranged in close contact with each other with the effective region of the second lens array approximating the smallest possible circle.

Femtosecond pulses in the focal region of lenses.

Abstract: A systematic theoretical and experimental study of focusing femtosecond light pulses by single lenses is presented. By evaluation of the diffraction integral the interplay of spherical and chromatic aberration is shown to determine the temporal as well as the spatial intensity distribution in the focal region of a lens. Conditions are derived under which the effect of spherical aberration dominates. Here a temporally unbroadened, in-focus pulse occurs while the spatial distribution is that expected from an annular lens aperture. If chromatic aberration is the major aberration, the in-focus pulses are considerably broadened. Both effects could clearly be measured with 100-fs pulses using a modified Michelson interferometer. In an intermediate parameter range both chromatic and spherical aberration contribute to the pulse broadening and to the spatial intensity pattern in a given plane in the focal region. From Fresnel diffraction we expect a weak-intensity distribution to precede the in-focus pulse on the axis. Another weak intensity peak is produced by the pulse traveling on axis. By measuring its separation from the main pulse in the marginal focal plane one can estiamte the aberration parameters.

Colored microlens array and method of manufacturing same

Abstract: A colored microlens array which functions as both a color filter array of different color filter layers and transparent microlenses. The colored microlens array has a transparent basic layer and a plurality of colored microlenses of different colors formed on the transparent basic layer in two dimensional arrangement in accordance with at least one basic color arrangement pattern. The colored microlenses are manufactured by forming semispherical lens forming layer portions on the respective color filter layers of the color filter array and by etching the color filter layers with the formed semispherical lens forming layer portions as a mask, to change in shape the respective color filter layers into the semispherical lenses, respectively. The colored microlenses are applied to solid-state image sensing devices, color liquid crystal display units, etc.

Optical device with two lens arrays with the second array pitch an integral multiple of the first array pitch

Abstract: A three-dimensional display comprises a spatial light modulator (13), such as a liquid crystal display, sandwiched between first and second lenticular screens (12, 16). The pitch of the lenticules of the second screen (16) is an integral multiple of that of the first screen (12). The spatial light modulator (13) comprises a plurality of cells aligned with the lenticules of the first screen (12). A linear array of sequentially illuminated light sources (1-8) is focused by an optical system (10) into a plurality of collimated light beams with different angles of incidence on the first screen (12). For each illumination of the light sources, the spatial light modulator carries a plurality of 2D interlaced views.

Synthetic aperture based real time holographic imaging

Abstract: Apparatus, system, and method is described wherein a synthetic aperture based sequence of image samples are generated with respect to a subject to be stereoscopically imaged. These sample images are presented to the spaced inputs of a holographic integrated combiner screen to be presented at an output aperture in laterally spaced mutual positioning. That spacing is selected, in one aspect, as one-half of the interpupillary distance of human eyes and thus binocular stereoscopic viewing at the aperture is achieved. The combiner screen may be utilized in conjunction with a holographic optical image combiner architecture which additionally employs a lens assembly such as a projecting lens to generate multi-zone outputs, each zone of which may be presented for stereoscopic viewing at a discrete viewing station. Correction for chromatic aberration of the holographic optical components is described.

Compensation of higher-order frequency-dependent phase terms in chirped-pulse amplification systems.

Abstract: We have developed a system that provides monotonic tuning of the higher-order frequency-dependent phase of ultrashort laser pulses. This technique utilizes geometric aberrations that arise from adjustments to the relative alignment of the elements of an air-spaced doublet lens. In a system such as a diffraction-grating stretcher, the spectral components of the optical pulses are spatially dispersed, and lens aberrations introduce frequency-dependent phase shifts. A numerical model of a general chirped-pulsed amplification system has been developed and verified by comparison with experimental and analytical results. Numerical results indicating that higher-order phase terms can be compensated by a properly adjusted air-spaced doublet design within the pulse stretcher are presented.

Fresnel and refractive lenses for X-rays

Abstract: We present a Gaussian beam analysis of X-ray refractive and Fresnel lenses. The X-ray refractive lens is featured by an intrinsic soft (Gaussian) aperture due to strong absorption of X-rays by materials. We defined a parameter N0, the critical Fresnel number (CFN), to describe this optical property. The values of N0 for all practical materials are below 1000 for photon energies exceeding 30 eV, still lower for high-Z materials. The maximum effective Fresnel number of a lens is determined by its material to be 2N0 and its maximum enhancement of X-ray intensity is limited to (2πN0)2, independent of its shape. We found that the refractive lens is likely to be useful for manipulating nearly diffraction limited beam in the hard X-ray region and its application is severely restricted by available fabrication capabilities today. X-ray Fresnel lenses, both in cylindrical and linear forms, are proposed as superior focusing elements for hard X-rays. Their high efficiency, up to 100% in optimal construction, will enable us to manipulate beams with multiple lenses and obtain higher performance optics. Their design and fabrication are discussed in reference to those of X-ray Fresnel zone plates and micro Fresnel lenses for optoelectronics.