Abstract: A solid imaging apparatus and method employing levels of exposure varied with gray scale or time or both of digitally light projected image of a cross-section of a three-dimensional object on a solidifiable photopolymer build material. The gray scale levels of exposure of projected pixels permits the polymerization boundaries in projected boundary pixels to be controlled to achieve preserved image features in a three-dimensional object and smooth out rough or uneven edges that would otherwise occur using digital light projectors that are limited by the number of pixels in an image projected over the size of the image. Software is used to control intensity parameters applied to pixels to be illuminated in the image projected in the cross-section being exposed in the image plane.

Abstract: A solid imaging apparatus and method employing levels of exposure varied with gray scale or time or both of digitally light projected image of a cross-section of a three-dimensional object on a solidifiable photopolymer build material. The gray scale levels of exposure of projected pixels permits the polymerization boundaries in projected boundary pixels to be controlled to achieve preserved image features in a three-dimensional object and smooth out rough or uneven edges that would otherwise occur using digital light projectors that are limited by the number of pixels in an image projected over the size of the image. Software is used to control intensity parameters applied to pixels to be illuminated in the image projected in the cross-section being exposed in the image plane.

Abstract: A solid imaging apparatus and method employing sub-pixel shifting in multiple exposures of the digitally light projected image of a cross-section of a three-dimensional object on a solidifiable liquid medium. The multiple exposures provide increased resolution, preserving image features in a three-dimensional object and smoothing out rough or uneven edges that would otherwise be occur using digital light projectors that are limited by the number of pixels in an image projected over the size of the image. Algorithms are used to select pixels to be illuminated within the boundary of each image projected in the cross-section being exposed.

Abstract: A solid imaging apparatus and method employing sub-pixel shifting in multiple exposures of the digitally light projected image of a cross-section of a three-dimensional object on a solidifiable liquid medium. The multiple exposures provide increased resolution, preserving image features in a three-dimensional object and smoothing out rough or uneven edges that would otherwise be occur using digital light projectors that are limited by the number of pixels in an image projected over the size of the image. Algorithms are used to select pixels to be illuminated within the boundary of each image projected in the cross-section being exposed.

Abstract: A solid imaging apparatus and method employing build material transfer means effective to transfer solidifiable liquid build material from a first side of a radiation transparent build material carrier to a receiving substrate without entrapping air bubbles in layers of transferred solidifiable liquid build material and to cleanly separate the solidified build material from the radiation transparent build material carrier as each layer is formed during the layerwise building of a three-dimensional object. An expandable membrane forming an arcuate dome and a reciprocatible flexible film are employed to effect transfer of the solidifiable liquid build material.

Abstract: An inert gas dispenser for mounting to a process equipment functional window is provided to dispense an inert gas in a laminar flow at an effective velocity across the exposed surface to form a curtain of inert gas across the exposed surface to prevent a build-up of chemical by-product from the powder material during laser sintering. The gas flow rate is characteristic of a flow geometry having a Reynolds number below the turbulent range. The diffuser is used in a laser sintering system.

Abstract: A solid imaging apparatus and method employing sub-pixel shifting in multiple exposures of the digitally light projected image of a cross-section of a three-dimensional object on a solidifiable liquid medium. The multiple exposures provide increased resolution, preserving image features in a three-dimensional object and smoothing out rough or uneven edges that would otherwise be occur using digital light projectors that are limited by the number of pixels in an image projected over the size of the image. Algorithms are used to select pixels to be illuminated within the boundary of each image projected in the cross-section being exposed.

Abstract: A solid imaging apparatus and method employing levels of exposure varied with gray scale or time or both of digitally light projected image of a cross-section of a three-dimensional object on a solidifiable photopolymer build material. The gray scale levels of exposure of projected pixels permits the polymerization boundaries in projected boundary pixels to be controlled to achieve preserved image features in a three-dimensional object and smooth out rough or uneven edges that would otherwise occur using digital light projectors that are limited by the number of pixels in an image projected over the size of the image. Software is used to control intensity parameters applied to pixels to be illuminated in the image projected in the cross-section being exposed in the image plane.

Abstract: A laser scanning system in a rapid-protyping system is controlled during vector scanning by providing a commanded-position signal to each of first and second rotary motive devices to rotate respective mirrors of the scanning system, each mirror undergoing acceleration at the beginning of the vector, wherein the commanded-position signals are calculated based on physical mathematical modeling of the acceleration of the mirrors taking into account effects of inertia of the scanning system, and wherein actual positions of the mirrors are measured with fast-response devices and digital feedback control of the mirror positions is employed at a periodic rate sufficiently small to maintain a following error of the laser spot less than about 200 ?s at all times. A laser power control method employs a fast-response power meter for measuring laser power.

Abstract: An apparatus and a method of using the apparatus wherein a radiation emitter is positioned adjacent a sensor apparatus within a process chamber in a laser sinter system that emits radiation to the sensor apparatus and a calibration apparatus receives readings from the sensor apparatus to compare temperature sensings received from the sensor apparatus with set emission signals from the radiation emitter to adjust the temperature sensings to calibrate the sensor apparatus during the forming of a three-dimensional article. The calibration is done repeatedly during the build process of the three-dimensional article.

Abstract: The invention relates in general to calibrating a focused beam of energy in a solid freeform fabrication apparatus, and, in particular, to a method of measuring the propagation characteristics of the beam to produce beam propagation data. The beam propagation data can be used to verify that the beam is operating within tolerance, and/or produce a response that can be used to further calibrate the beam. The invention is particularly useful in determining asymmetric conditions in the beam. The beam propagation data is produced in accord with the “M2” standard for characterizing a beam. In one embodiment, the response indicates the beam is unacceptable for use in the apparatus. In another embodiment, the response is provided to calibrate the focal position of the beam. In still another embodiment, the response is provided to an adjustable beam that eliminates the asymmetric condition.

Abstract: Solid state lasers that use non-linear optical crystals to generate frequency tripled or quadrupled output in the ultraviolet have low lifetimes due to damage to the face of the non-linear crystal through which the ultraviolet signal exits. To prevent this damage, the tripling or quadrupling crystal is provided within a controlled environment that is maintained substantially free from contaminants such as silicon-bearing and organic compounds. The tripling or quadrupling crystal is enclosed within a tubular chamber with windows on the ends of the tube that provide optical access to the entrance and exit faces of the tripling or quadrupling crystal. All heating elements and alignment elements for the crystal are outside of the chamber. Because the crystal is stored within the hermetically sealed chamber, contaminants are not available within the environment of the crystal that could interact with the energetic photons of the ultraviolet output of the frequency multiplied solid state laser.

Abstract: An illumination system includes optics capable of adjusting the size of a beam of light and adjusting the focus of the beam of light. Spot size control optics adjusts the overall size of the beam of light and separately adjusts the ellipticity of the beam, primarily in one dimension. Light from the spot size control optics passes to focus control optics that control the overall focus of the beam of light and adjust the astigmatism of the beam by altering the focus position of the beam of light in one dimension. The laser system, the spot size control optics and the focus control optics are within an enclosure. Actuators under remote control from outside of the enclosure adjust both of the spot size control optics and focus control optics in the thermal environment of the illumination system.

Abstract: A rapid prototyping and manufacturing (e.g. stereolithography) method and apparatus for making three-dimensional objects on a layer by layer basis by selectively exposing layers of material to prescribed stimulation, using a beam having a first smaller diameter and a beam having a second larger diameter, to form laminae of the object. The power of the smaller beam is typically lower than the power of the larger beam. Object formation is controlled by data representing portions of the layers to be exposed with the larger beam (large spot portions) and those portions to be exposed with the smaller beam (small spot portions). In a preferred embodiment, portions exposed with the larger beam are formed first, for a given layer. Portions are exposed with the small beam next. Thereafter the entire perimeter of the laminae is traced using the small beam.

Abstract: A solid state laser includes a high absorption coefficient solid state gain medium such as Nd:YVO4 that is side pumped with a semiconductor laser diode array. The resonant cavity of the solid state laser is positioned so that the TEM00 mode is spaced from the face of the laser through which the laser is pumped by a distance sufficient to reduce diffraction losses but sufficiently near to allow coupling of pump light into the gain mode. The gain medium, the doping level of the gain medium, and the operating temperature of the pump laser are selected to efficiently couple pump light into the gain mode. The pump laser is positioned to side pump the gain medium without collimating or focusing optics between the pump laser and the face of the gain medium. A gap between the pump laser and the gain medium is empirically selected to match the angular extent of the pump laser output light to the height of the gain mode at the position of the gain mode fixed to optimize coupling and diffraction losses.

Abstract: A rapid prototyping and manufacturing (e.g. stereolithography) method and apparatus for producing three-dimensional objects by selectively subjecting a liquid or other fluid-like material to a beam of prescribed stimulation. In a preferred embodiment a source of prescribed stimulation is controlled to reduce or inhibit the production of the prescribed stimulation during at least some periods when the prescribed stimulation is not needed to expose the material. In another preferred embodiment, the source of stimulation is controlled to vary the quantity of prescribed stimulation that is produced and allowed to reach the material. In an additional preferred embodiment control of laser output occurs based on a combination of supplying a regulated amount of voltage to an AOM in conjunction with temporary sensing of laser power and a known desired power to attain.

Abstract: A method and apparatus for building three-dimensional objects having an internal structure, wherein the structure is discontinuous and is composed from a plurality of patterns and bridging patterns formed on a plurality of levels, wherein a bridging level and pattern reside between previous and subsequent levels from which the bridging pattern obtains at least a portion of its pattern. A portion of the bridging pattern is obtained from the pattern on the previous level and a portion of the bridging pattern is obtained from the pattern on the subsequent level.

Abstract: Methods and apparatus for forming three-dimensional objects from a medium solidifiable when subjected to a beam of pulsed radiation wherein the pulses of radiation are made to occur when the beam is directed to desired pulsing locations on a target surface of the medium. Preferred embodiments of the instant invention include a pulsed laser assembly, including a laser and a pulse generation circuit, a control computer, a plurality of mirrors and mirror encoders. The computer controls the movement of the mirrors which guide the laser beam across the surface of the solidifiable medium. The pulsing of the laser beam is correlated to the position of the mirrors and thus, is not dependent upon time. Pulsing linked to position of beam placement allows controlled and repeatable use of a pulsed beam for the formation of objects.

Abstract: Embodiments of the instant invention are directed to laser exposure system that employs a pulsed solid state laser to provide a reactive response wavelength and a pulse repetition rate specifically optimized for application to solidification of a liquid photopolymer in a stereolithographic process. The solid state laser employs two second harmonic crystals for generating an emission wavelength at about 320-345 nm and a pulse repetition rate, wherein the pulse repetition rate is selected such that a pulse separation at the target surface results which is less than a diameter of the beam when the beam is being scanned at a desired velocity and an average exposure deposited by the beam is equal to a desired amount.

Abstract: A solid-state laser includes a high-absorption coefficient solid-state gain medium such as Nd:YVO.sub.4 that is side pumped with a semiconductor laser diode array. The resonant cavity of the solid-state laser is positioned so that the TEM.sub.00 mode is spaced from the face of the laser through which the laser is pumped by a distance sufficient to reduce diffraction losses but sufficiently near to allow coupling of pump light into the gain mode. The gain medium, the doping level of the gain medium, and the operating temperature of the pump laser are selected to efficiently couple pump light into the gain mode. The pump laser is positioned to side pump the gain medium without collimating or focusing optics between the pump laser and the face of the gain medium. A gap between the pump laser and the gain medium is empirically selected to match the angular extent of the pump laser output light to the height of the gain mode at the position of the gain mode fixed to optimize coupling and diffraction losses.