JP2002316364A - Beam profile measuring device and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for measuring the overall intensity and power of a beam by measuring the intensity profile of the beam, with regard to an optical three-dimensional shaping process. SOLUTION: In a sensor for beam profile measurement equipped with a pinhole plate and an optical detector arranged behind the former, a beam spot is transferred and consequently, the sensor for beam profile measurement measures an intensity which is respectively covered by some of different regions inside the beam spot. Software interrelated with the sensor for beam profile measurement controls a beam scan mechanism in a computer to transfer the beam spot onto a pinhole. Further, the software controls the mechanism to make the beam spot traverse over the pinhole and thus the intensity profile of the beam is obtained. A related device and a related method for the calibration and standardization of a three-dimensional shaping device are disclosed. In addition, a related device and a related method for correcting a positional deviation over time in the process of shaping a three-dimensional object are revealed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to an apparatus and method for measuring a beam of electromagnetic radiation or a beam of particles, and more particularly, to a novel apparatus for measuring the intensity profile of a beam. And new methods, and related applications for the production of three-dimensional objects by three-dimensional modeling.

[0002] This application is related to US Patent Application Nos. 182,823, 182,830, filed April 18, 1988.
Nos. 183, 016, 183, 015, 18
Nos. 2,801, 183, 014, and 183,
No. 012, all of which are incorporated herein by reference in their entirety. US Patent Application Nos. 182,830 and 183,01
Nos. 6,183,014 and 183,012 were filed on Nov. 8, 1988, the entire contents of which are incorporated herein by reference. The application numbers of the continuation-in-part application are (No. 182,830) Nos. 269,801 and 2
No. 68,806, No. 268,337, No. 268,90
No. 7, (about No. 183,016) No. 268, 42
No. 9, (No. 183,014) No. 268,40
No. 8 and (No. 183,012) No. 26
No. 8,428. US Patent Application No. 269,80
No. 1 continuation application was filed on March 31, 1989, the entire contents of which are incorporated herein by reference. The Lyon & Lyon case reference number of the continuation application is 186/195.

[0003] The entire contents of the following two manuals are also incorporated herein by reference.

[0004] 3D Systems, November 1987,
Beta site user's manual and service manual.

[0005] 3D Systems, October 1987,
Beta Release, first draft software manual.

Further, the following appendix is attached to this specification, and the contents of this appendix are also included in the disclosure content of this specification.

Appendix A: Software vendors other than 3D Systems, as of April 13, 1988.

[0008]

2. Description of the Related Art Recently, a "solid modeling" system as described in U.S. Pat. No. 4,575,330 entitled "Apparatus for manufacturing three-dimensional objects by solid modeling" has been used. . This U.S. Pat. No. 4,575,330
The disclosure of this item is hereby incorporated by reference in its entirety. Basically, stereolithography is performed by successively printing sections of photopolymerizable liquid or similar until all of the thin layers representing each section of the article are joined together to form the entire part. , A method for automatically forming complex plastic parts. In this technique, the parts are literally grown from within a container containing liquid plastic. This manufacturing method is very effective for quickly bringing a design idea into a physical form and for manufacturing a prototype.

[0009] The photopolymerizable liquid (photosensitive polymer) changes from a liquid to a solid where light is present, and the ultraviolet light (U
Its photopolymerization rate under V) is sufficient for a practical model building material. When making the part, the unpolymerized material remains in the container still usable and the part is made continuously. UV laser is U
It is used to generate a small intense beam spot of V light. This beam spot is moved over the surface of the liquid by a scanning device of the XY axis reflecting mirror type using a galvanometer mirror. The scanning device is driven by a computer that generates vectors or the like. Precise and complex models can be produced quickly with this technique.

[0010] The laser, scanning device, container for the photopolymerizable liquid, and the elevator used with the control computer combine with each other to form a three-dimensional modeling device called an "SLA". SLA is programmed to automatically produce plastic parts by "drawing" one cross section at a time and layering them one by one.

[0011] Stereolithography is an unprecedented new way to quickly produce complex or simple parts without the need for tools.

[0012]

Since the technique of three-dimensional printing relies on the use of a computer to generate a cross-sectional pattern, a data link to CAD / CAM necessarily exists.

In order for stereolithography to be effective, the system must focus on the beam (beam) in order to carry out the precise and effective production of parts (objects produced by stereolithography are referred to as "parts"). It is necessary to have information on the degree of focusing of the spot), the laser beam oscillation mode, the beam power, the intensity distribution or intensity profile, and the temporal displacement of the scanning system of the laser for writing. The beam must be substantially focused at the surface of the photopolymerizable liquid. The laser mode, the intensity distribution, and the beam power, as well as the scanning speed, are important factors that determine the curing depth and width of the curing mark on the working medium. The "time shift" of the scanning system must be checked and corrected periodically.

The beam profile (beam intensity profile) measurement has useful information about the beam because it can help achieve the following objectives:

1. To focus the optical system and correct aberrations such as astigmatism.

2. Measurement of beam power (performed daily).

3. Check the laser mode and change the mode.

4. Compensation for positional deviation of laser scanning system over time.

5. Recording of positional deviation over time for subsequent analysis of changes.

6. To automatically calibrate the scanning device.

7. To be able to easily control the position of the beam spot to perform other measurements (eg, separately measuring the beam power to find a calibration factor for the power of the system).

8. Be able to predict the size and shape of cured traces of cured plastic.

Accordingly, there is provided an apparatus and method for rapidly determining a beam profile to calibrate and normalize a stereolithography device and to correct for changes over time of a reflective mirror positioning system of the stereolithography device, In particular, a device useful for a three-dimensional modeling device is required.

[0024]

SUMMARY OF THE INVENTION Briefly and generally speaking, the present invention provides a new and improved apparatus and method for measuring a beam profile. The apparatus comprises a sensor means for measuring the intensity borne by a part of the beam spot when the beam is projected onto the sensor means, and a sensor for measuring the intensity of the whole or a part of the beam spot. Means for changing the vertical position of the sensor means along a plane substantially perpendicular to the optical path followed by the beam for measuring the intensity.
A method for measuring a beam profile comprises measuring the intensity of a region within a beam spot having a preselected size along a plane substantially perpendicular to an optical path followed by the beam; By repeating the measuring step for some other area in the beam spot along the plane.

The apparatus and method described above creates an intensity map of the beam along a plane substantially perpendicular to the optical path followed by the beam. The intensity map indicates the intensity for each portion of the beam spot having a preselected size. The intensity profile obtained in this way can be used not only for calculating the beam power (the conversion rate to the beam power is known) but also for checking the degree of convergence of the beam and adjusting the focus. it can. The strength profile can also be used to predict the cure depth and width of the cure marks of the plastic created on the working medium. The beam profile measurement device acts as a fixed reference point and can be used to detect "time offset" of the beam scanning device by determining the scanning device coordinates of the beam center. The device also recalibrates a positioning "map" or table that determines the orientation of the scanning device in translating the computer-generated design to the actual dimensions on the liquid surface that is hardening for object formation. Can be used for

That is, one beam profile measuring apparatus according to the present invention is a method for curing a working medium which is cured upon exposure to a beam spot by continuously curing the working medium in a thin layer adjacent to the surface of the working medium. A beam profile measurement device for measuring an intensity profile of the beam spot in a three-dimensional modeling device for modeling a three-dimensional object, wherein the beam profile measurement device is disposed at a position fixed relative to the surface, and the beam At least one sensor means for measuring the intensity profile of the beam spot by measuring the intensity of each of a plurality of different portions of the spot having a preselected size. It is a beam profile measuring device.

[0027] The beam profile measuring apparatus according to the present invention may further comprise scanning means for positioning the beam spot on the at least one sensor means.

The beam profile measuring apparatus according to the present invention may be used to determine the hardening depth of the hardened mark of the working medium by the beam spot, or to determine the hardening depth of the working medium on the surface. The degree of convergence of the above-mentioned beam spot can be checked, and the beam power of the above-mentioned beam spot can be measured.

Further, one beam profile measuring method according to the present invention is a method for curing a working medium which is cured upon exposure to a beam spot by continuously curing the working medium on the surface of the working medium in a thin layer adjacent to the working medium. A beam profile measuring method for measuring an intensity profile of a beam spot in a three-dimensional modeling apparatus for modeling a three-dimensional object, wherein at least one beam is arranged at a position fixed relative to the surface. Measuring the intensity profile of the beam spot by measuring the intensity borne by each of a plurality of different regions having a preselected size within the beam spot using the sensor means of This is a beam profile measurement method including a step of performing the following.

Another device according to the invention determines the cure depth of a cure mark of a working medium by means of the beam spot, comprising a beam profile measuring means comprising at least one sensor means capable of detecting the beam spot. Device.

Further, another method according to the present invention includes a step of obtaining an intensity profile of a beam spot and a step of calculating a curing depth of a curing mark of a working medium by the beam spot based on the intensity profile. And a method for determining the above-mentioned curing depth of the above-mentioned curing mark.

Another device according to the invention is a device for determining the degree of convergence of the beam spot on the surface of the working medium, comprising a beam profile measuring means comprising at least one sensor means capable of detecting the beam spot. It is.

Still another method according to the present invention is a step of obtaining an intensity profile of a beam spot, and a step of calculating a degree of convergence of the beam spot on a surface of a working medium based on the intensity profile. And a method for examining the degree of convergence on the surface.

Another apparatus according to the present invention is an apparatus for measuring the beam power of the above-mentioned beam spot, comprising a beam profile measuring means including at least one sensor means capable of detecting the beam spot.

Still another method according to the present invention includes the steps of obtaining an intensity profile of a beam spot, and calculating a beam power of the beam spot based on the intensity profile. It is a method of measuring power.

The above-described apparatus and method have important economic advantages. This is because the measurement of the beam profile by the devices and methods mentioned above uses the current computing system and the light beam positioning system already built into the stereolithography device.

While current systems refer to "laser beam systems" and "XY galvanometer mirror scanning systems", other possible systems having different energy sources or positioning means or combinations thereof are also described above. It is clear that each advantage can be applied.

The present invention provides a new and improved apparatus and method related to standardization and calibration of a three-dimensional printing apparatus.

In a three-dimensional part manufacturing apparatus, the reaction means (laser beam according to the preferred embodiment) of the working medium (according to the preferred embodiment, a designated surface with a photopolymerizable liquid). Devices and methods are needed to standardize and calibrate the emission. The precise positioning of the reaction means in the working medium is easy according to the invention,
This is possible by installing at least one sensor arranged at a fixed position relative to the surface of the working medium. The sensor detects the presence of the reaction means. A storage means is provided for storing other information, including positioning information, which causes the responsive means to be accurately directed towards the sensor. According to a preferred embodiment, the stored look-up table or stored reference map is populated with specific positioning information for each of a number of specific locations on the working medium surface. Standard linear interpolation techniques are used to determine the positioning information and are useful in directing the responsive means in the direction of each position falling between each position in the look-up table.

Accordingly, it is an object of the present invention to provide an apparatus and method for accurately calibrating and standardizing a three-dimensional printing apparatus.

It is still another object of the present invention to provide an improved and more precise method and apparatus for beam positioning.

The present invention also provides a related new and improved apparatus and method for correcting misalignment of a reflective mirror type positioning system over time to provide improved precision and repeatability. It is in.

A three-dimensional object, or "part," can be fabricated from a medium that can be exposed and cured by a stereolithography device to a reaction means that is scanned in a preselected manner on a designated surface of the medium. it can. In this manner, successive adjacent thin layers of cured media forming the part are stacked.

Thermal, wear and other effects can cause the positioning means for positioning the reaction means to shift over time so that the reaction means is no longer repeatedly directed to the same location. There is. To mitigate such displacement over time, the present invention employs at least one sensor means capable of detecting the application of a responsive means to the sensor means. The sensor means is arranged at a predetermined position fixed relative to the surface of the medium. The positioning means can position and apply the reaction means at an appropriate location, and can apply the reaction means to the sensor means. The means for outputting the sensor position for viewing provides information on the sensor position for viewing, indicating the position of the sensor means as viewed from the reaction means when the responding means is applied to the sensor means. Similarly, storage means is used to contain past sensor position information, including the previous viewing position of the sensor means. The present invention also includes a comparison unit for comparing the current sensor position information with the past sensor position information, and the comparison unit removes the effect of the positional deviation of the pointing position of the reaction unit with time, thereby setting the positioning unit. It has the ability to determine the correction of the misregistration over time, which is needed to adjust.

The above and other objects and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings of illustrative embodiments.

[0046]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A stereolithography system in which the apparatus and method of the preferred embodiment of the present invention are used is to respond to an appropriate synergistic stimulus, such as the impingement of an impinging radiation beam, an electron or other particle beam. A three-dimensional object is created by creating a cross-sectional pattern of the object formed on a selected surface of a liquid medium, such as a UV curable liquid, having the ability to change its physical state. The successive contacting laminae corresponding to the continuous cross section of the object are automatically formed and joined, resulting in the shaping of the object consisting of a stepped lamina. Thereby, a three-dimensional object is formed and grown from a substantially superficial or plate-like plane of the liquid medium throughout the forming process.

The general nature of this technique is illustrated by the flow charts and drawings of FIGS. 1-5.

FIG. 4 is a vertical sectional view of the three-dimensional printing system. The container 21 contains a UV curable liquid or equivalent and has a designated work surface 23. A programmable light source 26 of ultraviolet light or the like illuminates the plane of the surface 23 with a beam spot 27 of ultraviolet light.
Beam spot 27 is movable across surface 23 by the movement of a reflecting mirror or other optical or mechanical element (not shown in FIG. 4) used with light source 26. The position of the beam spot 27 on the surface 23 is
It is controlled by a computer control system 28. This system 28 is created by the data generator 20 which is a CAD design system or equivalent
Controlled by CAD data sent to the computerized conversion system 21 in a manner or an equivalent manner. The computerized conversion system 21 processes information defining an object to reduce stress, curl, and distortion, and increase resolution, strength, and reproduction accuracy.

The movable lift 2 inside the container 21
9 can be selectively moved up and down, the position of which is controlled by the system 28. When the apparatus is operated, combined thin layers, such as 30a, 30b, 30c, are created in stages, producing a three-dimensional object 30.

The surface of the UV-curable liquid 22 is maintained at a constant liquid level in the container 21 and has a beam spot of UV light or other light having sufficient strength to cure the liquid and convert it into a solid material. Move on the work surface 23 according to a programmed method. If the liquid 22 has hardened to form a solid material, the elevator 29, which was initially just below the surface 23, is lowered from the surface in a programmed manner by some suitable drive. In this way, the initially formed solid material is lowered below the surface and a new liquid 22 flows over the surface 23. A portion of this new liquid is converted into a solid material by the sequentially programmed beam spot 27 of UV light, and the new material is bonded together to the underlying material. This process continues until the three-dimensional object 30 is completely formed. The object 30 is then removed from the container 21 and the device is ready to make another object. This allows the next object to be produced, or a new object to be produced by modifying the program of the computer 28.

The light source 26 of the stereolithography system according to the preferred embodiment of the present invention is typically a helium-cadmium ultraviolet laser, such as 4240-N, manufactured by Reconix, Inc. of Sunny Valley, California.
There is a HeCd multimode laser.

A commercially available three-dimensional modeling system is shown in FIGS.
Will have additional components and subsystems in addition to the apparatus illustrated schematically. For example, a commercially available system will have a frame, enclosure, and control panel. Also, means should be provided for shielding the operator from extreme UV and visible light, and it is possible to provide means for observing the object 30 while it is being formed. Commercially available equipment is also provided with safety measures to remove ozone and harmful poisons, in addition to the usual high pressure security and interlocks. Some commercially available devices will have means for the purpose of effectively protecting sensitive electronic equipment from electronic noise sources.

Commercially available SLA is a self-contained system that interacts directly with the user's CAD system. A commercially available SLA that includes a preferred embodiment of the device of the present invention is shown in FIGS. 6 and 7 and consists of four main components. A SLICE computer terminal, an electronic cabinet assembly, an optical system assembly, and a chamber assembly. FIG. 5 is a block diagram of a commercially available SLA.

The electronic cabinet assembly is composed of a processing computer, a keyboard, a monitor, a power supply, an AC power distribution board, and a control board. The computer assembly includes a terminal control plug-in type circuit board, a high-speed scanning reflection mirror, and a vertical (Z stage) elevator. The laser power supply, dynamic mirror, and elevator drive are located at the bottom of the cabinet.

The control panel is provided with a power switch and a display, a chamber light switch and a display, a laser operation display, and a shutter open display.

The operation and maintenance parameters include fault diagnosis information and laser function information and are usually displayed on a monitor. All operations are performed on the keyboard. Work surfaces around the keyboard and the computer are covered with hormica (common name of surface finishing material) or the like to maintain cleanliness and long life.

FIG. 8 shows a helium cadmium (He).
Cd) Shows that laser 100 and optical components are installed on top of electronics cabinet and chamber assembly 102. The base carrying the laser and optical components can be accessed for service by removing the separate cover.
For safety, unlocking the cover lock requires special tools,
When the cover is removed, the interlock switch operates. The interlock activates a solenoid controlled shutter to block the laser beam, regardless of which cover is removed.

As shown in FIG. 8, a shutter assembly 104, two 90-degree beam direction changing mirrors 106 and 108, a beam expander 110, and XY are provided on an optical system base.
Axial scanning mirror assembly 112 and precision optical window 1
14 are installed. A rotary solenoid driven shutter is located at the laser output and rotates to block the beam when the safety interlock is opened. 90
The degree beam direction changing mirrors 106 and 108 reflect the laser beam toward the next optical component. The beam expander 110 expands the laser beam and then focuses on the liquid surface. The fast scanning mirror directs the laser beam at a vector on the resin to be scanned. A two-axis galvanometer mirror scanning head with two mirrors is available from General Scanning in Watertown, Mass. And has been found to be sufficient for this purpose. I have. In a preferred embodiment, a DX-2005 type servo, XY-0507
A galvanometer mirror XY scanning head was used. A quartz window 114 between the optical container and the reaction chamber allows only the laser beam to pass into the reaction chamber,
Others isolate the two regions.

The chamber assembly includes an environment-controlled chamber in which a table, a resin container, an elevator, and a sensor for measuring a beam profile are installed.

The chamber for forming the object is designed in consideration of the protection of the operator and to maintain a uniform operation state. The chamber is about 40 ° C (104 ° F)
The air is circulating through the filter.
Ceiling lights illuminate the resin container and work surface. The door interlock activates a shutter to shut off the laser beam when the door is opened.

The resin container is designed with minimal handling of the resin. The resin container is mounted in a chamber on a guide for aligning the resin container with an elevator and a table.

The object is formed on a vertical axis elevator, that is, a table attached to a Z stage. The pedestal is immersed in the resin container and adjusted so as to gradually descend while the object is being formed. To remove the formed part, raise the part to a position above the container. Thereafter, the platform is disconnected from the elevator and removed from the chamber for the next step. Usually, a processing dish is used to receive resin spills.

Two sensors 116 and 118 for measuring the beam profile according to the preferred embodiment of the present invention.
Are located on both sides of the resin container and the focus of the laser optics system is adjusted to match the sensor position (ie, 0.3 inches (about 0.8 cm) of the liquid surface from the galvanomirror scanner) The same distance as the distance to the lower point is attached as the distance in the radial direction from the galvanomirror scanning device; see FIG. 7). The scanning mirror is periodically commanded to direct the laser beam over a beam profile measurement sensor that measures the intensity profile. The intensity data is displayed on the terminal as a profile representing the intensity value or as a single number representing the overall (integrated) beam intensity. This information includes whether the reflector is clean and aligned, whether the laser is operating, whether the scanning mirror is displaced over time, and what parameter values determine the desired thickness and width. It is used to determine whether a hardened vector can be obtained.

Sensor 116 for measuring beam profile
And 118 are installed at symmetrical positions with respect to the center of the resin container (see FIG. 7A). Although not necessary, it is desirable that these have the same coordinates (with opposite signs) in the X and Y directions with respect to the container center. In other words, they are on the diagonal of the 3D modeling device. Such X direction and Y with respect to the container center
Hereinafter, the coordinates of the direction will be referred to as “offset values”. In FIG. 7 (a), the sensors 116 and 118 for measuring the beam profile are shown at the corners of the assembly of the chamber. The distance from the second scanning mirror on the optics base above the chamber assembly to the aperture of each beam profile measurement sensor is the focal length of the desired distance between the liquid and the scanning mirror plus a small increment. be equivalent to. Hereinafter, a focal length obtained by adding a small increment to a desired distance between the liquid and the scanning mirror is referred to as an “optically equivalent distance” as the distance between the liquid and the scanning mirror. SLA-1 sold by 3D Systems
In FIGS. 6 and 7, the distance from the scanning mirror to the liquid is about 27 inches (about 69 centimeters), and the slight increment is 0.3 inches (about 0.8 centimeters). ). Therefore, the focal length is about 27.3.
Inches (about 69.8 centimeters). Separating the sensors 116 and 118 for measuring the beam profile from the second scanning mirror by an optically equivalent distance to the photopolymerizable liquid is related to the designated surface of the photopolymerizable liquid in the SLA-1 resin container. Has the effect of detecting the best average degree of convergence. When the photopolymerizable liquid is at a desired level at the center of the resin container, the focal length of the laser beam is 0.3 mm above the surface of the photopolymerizable liquid.
This is the distance down to inches (about 0.8 cm). The convergence of the beam spot on the photopolymerizable liquid surface at the center of the resin container does not change much. SLA-
The focal length at the corner of one 12-inch resin container is about 1 inch (about 2.5 centimeters) above the surface of the photopolymerizable liquid. The focal length is the distance above the surface on a circle with a radius of 4.2 inches (about 10.7 centimeters) around the center of the photopolymerizable liquid surface. The arrangement of the sensor for measuring the beam profile at the focal length is intended to obtain an optimal beam profile, taking into account that the surface of the photopolymerizable liquid is usually not at the focal length of the laser.

FIG. 9 is a sectional view of a beam profile measuring sensor 35 of a preferred embodiment of the apparatus according to the present invention, and FIG. 10 is an upper plan view of a pinhole plate used for the beam profile measuring sensor. . The beam profile measuring sensor includes a stainless steel plate 40 in which four pinholes (passages) 45 of different sizes are etched. The diameter of these pinholes in the preferred embodiment is 0.0005 inch, 0.001 inch, 0.002 inch, and 0.004 inch (about 0.01 mm, about 0.03 mm, about 0.05 mm) , And about 0.1 mm)
It is. Each pinhole allows a portion of the laser beam 50 incident on the pinhole to reach a photodetector 55 below the thin steel plate 40. The purpose of providing several pinholes is to enable profile measurement of a beam with a wide range of incident power. One pinhole is devoted to measuring the intensity profile of a beam having a given incident power. SLA-1
For the helium-cadmium laser used in the mold, a single pinhole of 2 mil (about 0.03 mm) diameter has been found to be satisfactory. The beam is scanned along X and Y columns of the selected pinhole to form a two-dimensional profile of beam intensity.

As shown in FIG. 7A and particularly in FIG.
The beam profile measurement sensor 35 has two storage sections 60. The light beam 50 enters from the right side of FIG. 9 and moves toward the left side. When the resin container enters or exits the assembly section of the chamber, the beam profile measurement sensor is positioned at the corner of the assembly section of the chamber so as to prevent the beam profile measurement sensor from colliding with the resin container. It is installed (see FIG. 7A).

Returning to FIG. 9, the beam profile measuring sensor 35 is composed of two separate storage sections 60, a pinhole plate 40, and an ultraviolet transmission filter 70, and this filter 70 absorbs visible light. To prevent spurious readings caused by visible light. Filter 70
Is a 2 mm thick filter glass of the type Schott YG-11, which has been found to meet this purpose of the preferred embodiment. This filter has adequate transmission characteristics in the wavelength range of 300-310 nanometers, and has very low transmittance at other wavelengths. A one millimeter thick filter material of the type HOYA U-350 also meets the purpose.

Below the filter 70 in the housing, there is a photodiode detector 55, which detects the ultraviolet light passing through the filter 70 from the pinhole 45.
An EEG Vactec, VTS3072 type ultra-blue enhancing photodiode has been found to be suitable for this purpose. The output from the photodiode is sent to a current-voltage amplifier (not shown). OP07 type current-voltage amplifiers are well known to those skilled in the art and have been found to be usable for this purpose.

The pinhole plate 40 of the beam profile measuring sensor 35 is covered with a quartz filter (not shown). The quartz filter is cleanable and protects the beam profile sensor from dust and dripping of the photopolymerizable liquid. The quartz filter should be coated to prevent internal reflections when the photodetector is not perpendicular to the beam and to prevent false shape measurements. Optionally, a light diffuser (not shown) can be used between the pinholes. This is to assist the filter and prevent damage to the optical components.

FIG. 11 is a block diagram showing an apparatus according to a preferred embodiment of the present invention. Essential to this invention is
Computer for control and analysis. This computer receives input from programs, keyboards, etc.
The result can be displayed via a printer or a terminal. The control and analysis computer transmits a mirror positioning command to a mirror positioning system that adjusts the XY scanning mirror. The laser beam is focused by the optics shown in FIG. 8 to reach the XY scanning mirrors and is directed by these mirrors to one of the beam profile measurement sensors. For the purpose of correcting misregistration over time, it is recommended to use two sensors for measuring the beam profile. The signal from the beam profile measurement sensor is converted into a signal that can be read by a computer. This signal is then returned to the control and analysis computer for processing as described below.

Physically speaking, the beam profile measuring method according to the present invention moves a beam to each array point of a pinhole plate centered on the optimally known position of the pinhole. As a result, different areas within the beam spot illuminate the pinhole, are transmitted through the pinhole, are detected by the photodiodes, and are converted into numerical signals that can be analyzed by a computer. An intensity profile summarizing the intensity of each different region in the beam spot is created by a computer (see FIG. 16).
This is the "intensity profile" of the beam.

FIG. 12 is a functional block diagram showing a method for creating a beam profile according to a preferred embodiment of the present invention. The best known position of the pinhole on the beam profile measurement sensor is retrieved from memory by the control and analysis computer and transmitted to the mirror positioning system to position the XY scanning mirror to direct the beam to this best known position. Is done. Through the beam positioning system, the control and analysis computer moves the beam to the first row and first column of each point of the rectangular array centered on the best known location. Thereafter, the intensity of the beam portion incident on the pinhole detected by the beam profile measuring sensor is read and stored together with a mirror positioning command corresponding to the intensity. The beam is then moved from the beginning to the end of the array point on a particular row or column, and the steps of reading and storing intensity values are repeated. The column or row array is then moved from beginning to end, and the move and read steps are performed for each column or row.

As a result, a reading of the beam intensity will be made for each point on the array (the "position" is known to the computer as a set of mirror positioning instructions). Standard analysis of the array of intensity values, performed by a control and analysis computer, is generally performed to generate a new optimal known position of the pinhole (the next time processing the first step of the profile scan). For use). This is performed irrespective of the detailed function actually being analyzed (see FIG. 15). According to this method, it has been found that the calculated optimal known position is very accurate and can be obtained with much higher accuracy than the size of the pinhole. Several suitable places were found,
If remembered, this control system
Alternatively, these values can be used with biaxial linear interpolation to move the beam to some intermediate location.

FIG. 13 is a functional block diagram for implementing the beam moving method and the method described with reference to FIG. The first step in moving the beam is to transmit beam positioning information about the desired location to the XY scanning mirror servo mechanism. Thereafter, the servo mechanism (either analog or digital) transmits a signal to the mirror driver to position the XY scanning mirror at the new location. The servo mechanism of the XY scanning mirror measures the actual position of the mirror driver, compares the actual position with the desired position, and adjusts the drive signal appropriately. The adjustment is
It continues within the specified values for the desired location.

FIG. 14 is a functional block diagram showing a method for reading the beam intensity and a method for performing the method of the preferred embodiment of the present invention. The first step is to convert the total amount of light passing through the pinhole into a signal proportional to the amount of light. In a preferred embodiment, this step is performed by a photodiode that measures the light incident through the pinhole and the filter. The current from the photodiode is transmitted to a current-to-voltage amplifier that generates a signal proportional to the amount of light received by the photodiode. Amplifying the signal (which is proportional to the intensity) and providing a wide range of measurements is important for obtaining small but sufficient readings on the edge of the beam spot that would otherwise be missed. .

The next step is to measure a signal proportional to the amount of received light after this signal has been converted to a digital form for numerical analysis.

FIG. 15 is a functional block diagram illustrating the steps and analysis, and this analysis is related to the method described with reference to FIG. As shown in this figure, various steps and analyzes can be selected from the menu, the first five of which communicate to the profile scanning routine of FIG. In the first stage, the method described in FIG.
Scanning the intensity profile of the beam. The intensity profile can be displayed in numerical or graphical form. Optionally, the power can be calculated from the intensity profile as well as the new optimal known position of the pinhole used. Another possible step is to add the data generated in connection with the intensity profile of the beam to a history file and provide the option of displaying the history file. An additional possible step is to generally scan also a second separate sensor (in the preferred embodiment, another sensor for measuring the beam profile) to calculate the displacement information over time of the mirror positioning system. Then, an offset value and a gain value relating to the temporal displacement are calculated and displayed. Another possible step is to calculate and display the power of the beam, including summing the intensity of the profile and multiplying by the power conversion.

The power conversion rate can be determined, for example, using a process with a beam of known power, or by comparing the calibrated sensor power with the calculated power to determine the required power magnification. Can also be determined. Other features include calculating and displaying the degree of convergence of the beam spot, which may be due to the option of utilizing a special transformation of the intensity data used to calculate the degree of convergence of the beam spot, and Alternatively, it may be based on the use of known resin characteristics for estimating the shape and size of the cured mark of the photopolymerizable liquid. Other possible features include moving the beam to a desired location for start-up (to make parts) and testing, etc., where the option to search for a sensor from a new location or scan a profile is provided. Is also possible. A useful function is to search for sensor pinholes in a spiral motion reading mode. This may be necessary if the best known location of the pinhole is not accurate, i.e., if the scan of the array has gone past the best known location of the pinhole. The next step is to verify (by pinhole location) by testing or profile scanning. Yet another function is to use a sensor for beam profile measurement for calibration, which involves making a measurement of misregistration over time while obtaining a calibration diagram for a surface corresponding to the surface of the photopolymerizable liquid. . The last function is to store variables such as optimal known location, scale factor, resin properties, etc. in the computer.

FIG. 16 is a sample diagram of a laser beam intensity profile according to a preferred embodiment of the present invention. That number corresponds to the beam intensity measured from the preferred embodiment of the present invention. Numerical values are converted to integers for easy reading of the display.

The intensity profile generated according to the present invention can be used to calculate beam power and can be used to determine the cure of a photopolymerizable liquid (a photopolymerizable liquid solidified by exposure to a beam of UV light). Used to predict the shape and size of The results of the study are described below.

The beam intensity is measured by a beam profile measuring sensor when the beam is directed to each of the array points on the pinhole plate. Pinhole plates are generally
The plane is perpendicular to the optical path of the beam. The X and Y directions on this surface correspond to the directions in which the beam moves as one or more scanning mirrors rotate.

The coordinates of the arrays in the X and Y directions are 1 to i max and 1 to j max, respectively. (Generally, i
max and j max are each 22).

In general, a beam travels from point to point in the array with a travel time much shorter than the time the beam stays at a point. The interval between points is: S (mm) = scan step / scale factor [1].

The scanning step is typically 4 "bits"
The scale factor is usually 140 bits / mm. The scanning mirrors are 65535 (64K) each with a light beam rotation of 40 degrees.
Different positions can be obtained. This means that, in other words, one bit along the X or Y axis is 6.104 × 10
^-4 degrees of rotation. Since the distance from the mirror to the liquid surface is about 27 inches (about 69 centimeters), this rotation angle is 2.875 × 10 ^−4.
It corresponds to inches (7.303 × 10 ⁻³ mm), that is, 137 bits / mm, or about 140 bits / mm, which is the same.

The area of the array must be able to cover the entire beam spot (because it creates the most information about the beam spot, as well as the measurement of the entire beam spot is needed for beam power calibration). Also,
A sufficient number of points is needed to resolve the desired beam profile. Generally, the spacing between each point in the array is less than one tenth of its beam width. The diameter of the pinhole should be smaller than this resolution limit.

An "element" is a point (m,
It is a portion of the beam spot measured when the beam is pointed at n). Each element (m, n) is an intensity reading I
Take (m, n). The letters m and n mean the position in the X and Y directions in the array, ie, the array point. FIG.
Shows intensity readings in the array just considered.

The beam power is measured separately, and the power calibration factor K is derived from the following equation:

[0088] The power calibration factor K applies only to certain selected pinholes, measurement systems, and laser wavelengths. Individual power measurements must be performed on the beam after passing through the same number of optical surfaces on the beam path. These calculations also assume that the background optical signal has been removed and that the amplification factor of the amplifier has been compensated.

The power / unit area in the element (m, n) is obtained by the following equation.

Intensity (at element m, n) = K × I (m, n) / S ² (watt / mm ² ) [3] This is independent of whether the beam is stationary or moving. , The instantaneous intensity experienced by the small area of the element (m, n).

The beam has a velocity V (mm / sec) along the Y axis.
In the case of moving uniformly at the time and taking the same time as S / V to pass through each element, the exposure energy absorbed per unit area from the element (m, n) is as follows.

Element Exposure (m, n) = K × (I (m, n) / S ² ) · (S / V) (Joule / mm ² ) [4] This is the specific element (m, n) Exposure energy absorbed per unit area. The total beam exposure (absorbed beam energy) is as follows:

[0093] Physically speaking, this equation describes the situation where the beam traverses in the Y direction over an area having an area corresponding to the element size of the beam spot using the term element above. The area intersects with each element having the X coordinate m of the beam spot,
Therefore, when n changes from 0 to jmax, each region having an area of one element in each m is exposed over all the elements (m, n).

Although the calculations described above are based on individual elements, it is clear that integral values can be used. The movement is assumed to be along the Y axis for convenience. It can easily be determined along other directions of travel, which is necessary if the beam is asymmetric.

The speeds V corresponding to the variables SS and SP are as follows.

V = (SS / scale rate) (SP / 100,000) (mm / sec) [6] where SS = step size (bits / step) Generally, the scale rate is 140 bits / mm. is there.

SP / 100,000 = step cycle (second) (SP unit is the same unit as 10 microseconds). 1E6 = 1,000,000 is Joules / mm
² Joule / ^{m 2} or micro Joules / mm
^This is a conversion coefficient between ² .

Equations 5 and 6 describe the sensor or
Combined to calculate the total exposure (incident power or energy) at the liquid (photopolymerizable liquid) surface, represented by Z = 0, at a small area at position m when the beam moves in the Y direction. Can be used. That is, Finally, the absorption of the beam penetrating the liquid can be corrected according to Beer's law.

E (m, Z) = E (m, o) × exp (−Z / λ) [8] where λ is the depth of penetration (mm) E (m, o) is the surface The total exposure at
(M, z) is the exposure at a depth Z (mm) below the surface.

Since it can be assumed that the attenuation has no nonlinearity or time dependence with respect to absorption, it is simply represented by I (Z) = I (Z = 0) × exp (−Z / λ).

Obviously, it is possible to modify the above calculations appropriately, taking into account the deviations from the simplified situation for the absorption described above.

Photopolymerizable liquids have been experimentally shown to cure into gels if the exposure is greater than the critical value Ec, and thus the shape of the cured trace of the cured plastic for a given system. Can be calculated by calculating the trajectory of the point having the exposure Ec. E
c can be accurately and individually measured for each photopolymer. The "gel point" gives only the boundary of "cured part" to "uncured part" and Ec
Exposure gradients (related to penetration depth) at resin depths other than the depth boundary corresponding to are ignored. The strength of the part is likely to be related to the higher exposure, so the absorption properties should be chosen to give the optimum (highest) cure gradient. Also, the slope or penetration depth limits the optimal effective resolution in the Z direction. This is because slight variations in exposure (such as line-to-line variations) cannot be avoided, thus resulting in varying cure depths according to this variation in exposure.

Curing depth Zc for a certain X position (m)
(M) is derived by the following equation.

Zc (m) = λ × ln (E (m, Z = 0) / Ec) [9] The beam profile measured with sufficient reliability and accuracy has a curing depth determined only by the chemical properties of the resin. Used to predict the length. FIG. 17 illustrates two examples of prediction along the X and Y axes, respectively.
The profile function (m, Z) also allows the cure width to be automatically predicted as a function of cure depth (and "beam width" and "minimum surface angle" with appropriate changes). The formation and measurement of the "banjo top", i.e., cure marks cured by the beam to directly determine the shape and size of the cured photopolymerizable liquid, is only for checking. FIG. 18 shows a cross section of a test scan of the banjo top, which should be compared with FIG.

In order to display the profile of the predicted hardening mark, a correspondence diagram of the hardening depth versus the position is drawn for the beam spot. The scale factor for the distance across the beam is simple, and may simply be determined by selecting one row (or one column) as the dimension s according to the pixel or graphic display block. At this time,
The depth measure is λ / s pixels for each exposure multiplied by e. The only optional element is the depth zero, which is related to the exposure characteristic Ec in Equation 9 or the equivalent factor in Equation 7. The displayed effective depth is determined by the operating range of the intensity measurement system and whether the truncation at I (m, n) is above some suitable value near the noise level.

Calibration and Normalization As noted above, it is desirable to have an apparatus or method for calibrating the position of the reaction means with respect to the working medium in order to obtain improved precision and accuracy in the stereolithography machine. That is. The calibration procedure of the preferred embodiment of the present invention draws a "map" from the design in CAD space,
It is possible to derive the instruction for the actual SLA. In any automated modeling system, there are several sources of different errors that need to be corrected in the calibration process. This system has a pair of scanning mirrors in close proximity to each other, and if the simple map of the CAD dimension versus mirror angle remains uncorrected, stitch-like distortion will result. This is because the system also models a flat surface that extends far from a point on the surface closest to the mirror, so that a uniform increment of angle projects onto that surface as a progressively larger distance. Because. this is,
A major distortion in this system, it is possible to make geometric predictions so that corrections can be calculated. However, there are many other errors and distortions that need to be corrected, many of which are not easily predictable.

The calibration and normalization of the present invention is used in a wide range of applications and systems, and includes instructions to be sent to the scanning system to draw the indicated pattern on the work surface.
A "look-up table" that allows the D position to be translated is automatically created.

The term “normalization” can be used to indicate that more than one dimension is modified at a time,
On the other hand, "calibration" has the implicit meaning of providing a single correction factor for a system. The device in the preferred embodiment has a single position sensor (sensor for measuring the beam profile), which moves automatically for each array of positions on the work surface, and then each of these positions Record the substantial mirror positioning instructions needed to reach. In another preferred embodiment, a rectangular calibration plate with two-dimensionally arranged sensor pinholes is used to eliminate the need for sensor movement. In another preferred embodiment, the sensor pinholes that need to move only along a single axis are linear (one-dimensional).
Is used.

FIGS. 19 and 20 illustrate a rectangular calibration plate 200 of the preferred embodiment of the present invention.
The UV opaque metallization 206 is a substrate 204 made of a preferred material of quartz or Pyrex with a thickness of 1/8 inch to 1/4 inch (about 3.2 mm to about 6.4 mm). Provided by vapor deposition. In the preferred embodiment, 49 × 49 pinholes 202 arranged two-dimensionally are etched on the UV opaque metallization 206 at １ ／ inch (about 6.4 mm) intervals. The diameter of each etched pinhole is 0.004 inches ± 0.0005
Inches (about 0.1 ± 0.01 mm), but it is very important that the pinhole diameter be smaller than the beam diameter projected on the calibration plate to achieve the best resolution. That is what. A sensor (not shown) is mounted below the calibration plate and is positioned such that, when the calibration plate is used, it is accurately positioned at a fixed position relative to the working medium surface.

In a preferred embodiment of the present invention, two-dimensionally arranged 5.times.5 or 25 UV-sensitive photodiodes 208 are used with a calibration plate.

In this preferred embodiment, the UV light enters the pinhole because the UV light only passes through one of the pinholes and enters the calibration plate, and the calibration plate material tends to diffuse the incoming light. Light spreads horizontally beyond the exact location of the pinhole, and the 25 sensors described above are 49 ×
This is enough to cover the area of 49 pinholes.

A typical calibration procedure can be performed before shipping the SLA to a customer and after the mirror control system has been subjected to physical trauma that could invalidate the SLA calibration.

The actual calibration procedure uses a beam profile measurement methodology similar to the method for obtaining the “optimal position” of a pinhole from the center of the scan data.

The new "optimum position" is that for a square calibration plate where the pinholes are arranged two-dimensionally,
Determined for each row of pinholes in the case of a calibration plate with pinholes arranged in a straight line, and for each preset location when the sensor is located at a preset location. . Scanning each pinhole to find the look-up table that is actually used is not necessarily required. In a preferred embodiment of the present invention, 4
0x40 pinholes are arranged and mapped. In situations where the geometric distortion is small, or where the required accuracy is low, or other sources of distortion are properly and reliably corrected by interpolation correction,
Fewer pinholes may be used. Linear interpolation associated with the X and Y positions is used to determine mirror positioning for points falling between "optimal positions" stored in look-up tables in storage. The appropriate number of pinholes is determined by these considerations and from the time required to perform the calibration or from the system memory available to store the look-up table. The temporal displacement correction apparatus and method described below are optionally and preferably used with calibration to obtain more precise and more accurate results. Similarly, the same temporal displacement correction method and apparatus may be used during part fabrication to improve accuracy and precision.

The method according to the preferred embodiment of the present invention will now be briefly described.

First step: The operator inserts the calibration plate into the SLA modeling chamber so that each sensor pinhole of the calibration plate is located at a position where the liquid level is normally located, and performs sensors 1 and 2 (fixed). The delay time between each reading time between the positions of the measured beam profile measurement sensors 116 and 118) and the calibration plate (which can be regarded as “sensor 3”) is designated.

Second stage: The sensors 1 and 2 are repositioned to the positions to be positioned when the first profile scan occurs, and their coordinates are determined and recorded as mirror positioning information.

Third step: The center position of the calibration plate is determined by determining whether the position of the sensor 3, that is, the coordinates are within an allowable error range. The center coordinates of the calibration plate should match the center coordinates for mirror positioning. This arrangement allows the mirror to move equally and maximally in all directions.

Fourth step: The signal level obtained by the calibration plate (sensor 3) is set by reading the center pinhole of the calibration plate. (The pinhole at the center is
The beam profile is found by the sensor search algorithm defined by FIG. 1). The actual beam intensity is found by reading the sensor with and without the beam in the center pinhole. This reduces the background noise received by the sensor 3. Control of the signal level is adjusted by the operator until the sensitivity of the sensor is optimal.

Step 5: The calibration plate boundary is established by advancing the beam in a stepwise manner from the pinhole to the calibration plate boundary. (1 = west, 2 = north, 3 = south, 4 =
east).

A) In direction 1, a preset (bit /
By moving by the value of (pinhole separation distance), a pinhole is searched for along that direction. The bit indicates the change value of the mirror coordinates.

B) One more time after reading a known number of pinholes up to the boundary (bit / pinhole separation)
The minute is moved.

C) If the reading finds a pinhole there, the wrong pinhole has been read and the signal level has been improperly set, or the search has started at the center pin. Either a pinhole to the right of the hole. Return to the third stage.

D) If no pinhole is detected,
The left and right boundaries have been established.

E) The beam returns to the center pinhole and A
Search for the back boundary in the same way as -D.

F) Once all the boundaries have been determined through movements 1 and 2, the values indicating the position of the pinholes for movements 1, 2, 3, and 4 are indicated on the mirror bit plate by the "pinhole schematic separation map". Used to create ". After the movement 4, the beam is left in the pinhole (1, 1).

Step 6: Rapid search for all pinhole positions on the calibration plate. If the pinhole is no longer located, the beam will remain in the most likely optimal location as determined by the "schematic separation map of the pinhole" and will be operated to investigate the dust around the pinhole Urging people. After waiting, the search continues until the pinhole is located or the operator stops. If the operator so desires, the signal level can be reset at this stage. When the signal level is changed, the operator performs a quick search again from the pinhole (1, 1).

Seventh stage: After searching for all pinholes on the calibration plate by rapid search, a final search is performed after a necessary delay time from the first stage. Sensor 1 also determines the "calibration gain value" and "calibration offset value" corrections performed during the mirror bit move interval to the same location (end of each row) in the rapid and final search. And positions 2 are checked. These corrections are applied as proportionality factors to proportionally correct the position of each calibration point in a way that normalizes to a single combination of fixed reference locations for sensors 1 and 2.

Eighth stage: After the final search is completed, all the data of the gain value at calibration, the offset value at calibration, the intensity, and the position are stored. This completes the procedure.

Temporal displacement correction Temporal displacement correction is performed by using one or more beam profile measurement sensors (here, “sensor means”).
This is a procedure for periodically correcting the apparent position of the mirror positioning system to check the apparent position. Measuring the variation in the apparent position of one sensor is called “zero setting”
Of the mirror system can be corrected over time. In the case of two separate sensors, furthermore, correction of variations in the component size of the SLA due to thermal or other influences, such as extending the mirror operating range of the system and which cannot be compensated for by one sensor. enable. Other errors can be corrected by using multiple sensors, but the use of two beam profile measurement sensors in the preferred embodiment of the present invention is considered sufficient.

In a preferred embodiment of the present invention, the calibration operation is performed periodically. The calibration procedure uses a calibration plate with a large number of pinholes and a sensor to generate a table of mirror position settings in system memory corresponding to pre-fixed positions on the calibration plate.

While performing the calibration, the system periodically checks the apparent positions of the two sensors. Since these measurements are the values used to correct the calibration measurements for this temporal displacement value, the values are 2
They are all standardized as "standard values" indicating the current position of each sensor. After the part is formed, the same two sensors are again scanned periodically and the apparent position is used to correct for zero point variations from the time of calibration and for extended mirror operating range. This method has been found to eliminate 90% of the errors due to mirror displacement over time. The calibration procedure has already been described.

In a method and apparatus for correcting misregistration over time according to a preferred embodiment of the present invention, two beam profile measurements capable of detecting a laser beam when the laser beam is directed at a sensor by a mirror positioning system. The application sensor is located at a predetermined position which is fixed relative to the surface of the working medium which the reaction means can collide with and thereby solidify.

The laser beam is periodically directed at the sensor, and the sensor position output means provides a readout of the apparent position of the sensor. The current apparent position of the sensor is compared to past apparent sensor positions stored in the storage device, and the difference indicates the need to correct for misregistration over time.

For example, one sensor 1 is used, and this sensor 1 has a past apparent position of X = 20, Y = 20 and a current apparent position of X = 22, Y = 22. If, for example, a + 2X and + 2Y displacement has occurred over time, the mirror positioning system can apply an appropriate correction factor to direct the beam to the desired position. As another example, a sensor 2 is used in addition to the sensor 1, and the sensor 2 has X = 64000 and Y = 64.
000 at the time of calibration, and X = 6400
4. Assume that Y = 64004 has been obtained as the current apparent position. In this case, in addition to the + 2X, -2X linear movement over the entire system (two sensors arranged diagonally), the + 2X, + 1Y extension for the normalized distance between sensor 1 and sensor 2 is: is there. The ratio of the distance between the sensor 1 and the sensor 2 after the expansion to the normalized distance is referred to as a “gain value”. And we
For different relative positions with respect to the sensor 1, different proportions of expansion proportional to the above are expected and corrected. In making the correction, linear interpolation can be used to help the mirror positioning system correct for stretching due to misalignment over time.

Special computer software algorithms have been developed to achieve more accurate part fabrication using 3D modeling. This algorithm is known as the "temporal misregistration correction algorithm" and is considered to have two parts.

The first part is a code for determining the value of a variable to be used for correcting a temporal displacement. The second part is
Here is the code for the use of these variables in the correction of displacement over time.

The time-dependent displacement correction variables are as follows.

* The X-axis gain value is, in our example,
Call it DriftGain X.

* X-axis offset value of the first sensor
DriftOffset X * Y-axis gain value DriftGain Y * Y-axis offset value of first sensor DriftOffset
Y These variables are the values of each X,
Used to calculate the correction rate applied to the Y coordinate position. This correction is applied individually to each axis and has a gain (multiplier) value and an offset (addition) value for each axis. The correction is represented by the following equation.

Coordinate value after correction in a certain axis direction = (gain value × desired distance from the first sensor along the axis) + offset value of first sensor Here, gain value and offset value as variables Makes the ideal desired position in each axis direction correspond to the actual corrected coordinate position based on the measured values.

The displacement correction variable over time is determined at the beginning of each layer formation by using an algorithm for measuring the beam profile which is very similar to the algorithm in the beam program. 2 placed at the diagonal part of the resin container
The position of the beam profile measurement sensor is measured and calculated and compared with the ideal position stored in a data file on the disk. The difference between the measurement position of these two profile measurement sensors and the ideal position determines the value of the temporal displacement correction variable. Arranging two sensors for profile measurement at the diagonal of the scanning area optimizes each of the baselines along the X and Y axes, which are the basis for measuring the change in gain value.

The following Pascal function is a sample for calculating the value of the temporal displacement correction variable. 'R
The ef ′ variable is the reference position of the two beam profile measurement sensors read from the data file in the disk. The 'now' variable is the latest position of the two profile measurement sensors. Due to dynamic changes in the physical properties of the laser scanning system, the position held in the 'Now' variable is slightly different from the ideal reference position. It is the purpose of this function to utilize these positional differences to adjust the mirror direction immediately after.

For CorrectForDrift ... compute value of drift correctionvariables｝ procedure CorrectForDrift; Var quotient: Float Type; begin DriftGain X: = (Sensor2 NowX-Sensor1 NowX) / (Sensor 2Ref X-Sensor1 RefX;) DriftOffset X: = Sensor1 NowX; DriftGain Y: = (Sensor2 NowY-Sensor1 NowY) / (Sensor 2Ref Y-Sensor1 RefY;) DriftOffset Y: = Sensor1 NowY; end; The following Pascal procedure shows how the temporal displacement correction can be applied to a pair of coordinates after determining the temporal displacement correction variable. Note that the corrections for each axis are independent of each other.

Rif DriftCorfect ... correct coordinate pair for drift｝ procedure DriftCorrect (oldX, oldY: FloatType: Var newX, newY: FloatType); begin newX: = (oldX-Sensor1 RefX) * DriftGain X + DriftOffsetX; newY: = (oldY-Sensor1) RefY) * DriftGain Y + DriftOffsetY: end: The DriftCorreet procedure converts the drawing vector into a "feature" which is a highly optimized form of laser drawing used within 3D Systems software. It is used to modify the start and end coordinates of each drawing vector. After the latest position of the two beam profile measurement sensors is determined, CorrectF
orDrift is used only once per layer.

In practice, these routines are located in a special memory resident driver (known as STERIO) that can be used by different stereolithography application programs. This application program is responsible for detecting the position of the profile measurement sensor and transmits this position information to the special device driver.

BUILD STERREO Application used for part formation Program including correction of positional deviation over time; For each layer → Sending the position information of the server for performing three-dimensional modeling of various types of profile measurement sensors related to multiple tasks I do. Memory resident driver.

The procedure equivalent to the temporal displacement correction is SL
Performed at all calibration points during calibration of A. In a preferred embodiment, the displacement over time is determined at the end of the scan for each row having a pre-fixed position, and the correction is applied through linear interpolation of that row. The actual software implementation of such a modification routine is within the capabilities of those skilled in the art and will not be described further here.

While a particular form of the invention has been illustrated and described, it will be apparent from the foregoing description that many modifications can be made without departing from the spirit and scope of the invention. Therefore, other than by the appended claims,
The present invention is not limited.

Appendix A 34.166-34.169 '88 .4.13 Software status other than 3D Systems Corporation Slice Computer (NEC386) TM 386 / ix Operation System UNIX (registered trademark); System V Release 1.0.4 80386 TDCP Ethernet (registered) Trademark) support, MICOM version INTERACTIVE Systems Corporation, 2401 Colorado Avenue, 3rd Floor Santa Monica, Calivornia 90404 Process computer (WYSE 286) MS-DOS 3.21 Wyse Technology, 3571 N. First Street , San Jose, CA 95134) Q-DOS II version 2.00 Gazelle Systems, 42 North University Avenue, Suite 10 Provo, Utah 84601 FTP software PC / TCP file transfer program version 1.16 FTP software PC / TCP telnet Version 1.16 MICOM-Interlan, Inc., 155 Swanson Rd., Boxborough, MA 01719) April 13, 1988 SLA-1 Main parts list Laser: 1) Linconix, 1390 Borregas Abenue, Sunnyvale, CA 94089 A) 4240H He-Cd multimode laser B) 4240PS power supply 2) Omnichrome, 13620 Fifth Street, Chinno, CA 91710 A) 356XM He-Cd laser B) 100 power supply Scanning mirror: 1) General Scanning, Inc., 500 Arsonal Street, Watertown, MA 02172) A) P / N E00-Z2173 XY0507 scanning mirror B) P / N E00-DX2005 XY0507 scanning mirror controller Z-axis (vertical) elevator: 1) Dedal (Daedal, PO Box G, Harrison City, PA 15838) (Purchased through an agency) Pacific Technical Products, Inc. (Pacific Technical Products, 15901 Foothill Blvd., Sylmer, CA 91342) A) P / N 008-0324-3 14 inches・ 5 pitch linear table B) P / N MC5000-20 Motor drive control SLA-1 process Computers: 1) Wyse Technology, 3571 N. First Street, San Jose, CA 95134 (purchased through distributor) Peripheral Systems, Inc., 8107 Orion Avenue, Van Nuys, CA 91406) A) Wyse 286, Model 2200 (including the following) 1.40MB hard disk 2.PC AT keyboard 3.Monitor 4.Graphic card 5.Mathematical coprocessor 2) Tarnz Technologies, 8025 Sepulveda Blvd., Van Nuys, CA 91406) A) I / O board SLA-1 Slice computer: 1) NEC Information Systems, Inc., 1414 Massachusetts Avenue, Boxborough, MA 01719 (purchased through an agency) Peripheral Systems, Inc., 8107 Orion Avenue, Van Nuys, CA 91406 A) NEC PowerMate 386 Computer Beam Expander: 1) Optomio Design Optomeo Design Co., 901 18th St. Suite 203, Los Alamos, NM 67544) A) No. D10493 (4X) type beam expander

[Brief description of the drawings]

FIG. 1 is a flow chart illustrating a basic concept used when implementing a three-dimensional printing method.

FIG. 2 is a flow chart illustrating a basic concept used when implementing a three-dimensional printing method.

FIG. 3 is a flow chart illustrating a basic concept used when implementing a three-dimensional printing method.

FIG. 4 is a diagram combining a block diagram and a schematic vertical sectional view of a three-dimensional printing system.

FIG. 5 is a block diagram of a three-dimensional printing system.

FIG. 6 is an exploded view of main components in the three-dimensional printing system.
Perspective view

FIG. 7: Disassembly / disassembly of the main components in the 3D modeling system
Perspective view

FIG. 8 is a perspective view of a laser and optical system of a stereolithography system using a preferred embodiment of the present invention.

FIG. 9 is a schematic sectional view of a sensor for measuring a beam profile according to a preferred embodiment of the present invention.

FIG. 10 is a top plan view of a pinhole plate of the beam profile measurement sensor according to the preferred embodiment of the present invention.

FIG. 11 is a block diagram showing an apparatus according to a preferred embodiment of the present invention.

FIG. 12 is a functional block diagram of a preferred embodiment of a beam intensity profile deriving method according to the present invention;

FIG. 13 is a functional block diagram of a method of moving a beam when performing the method described with reference to FIG. 12;

14 is a functional block diagram of a method of reading the intensity of a part of a beam when the method described with reference to FIG. 12 is performed.

FIG. 15 is a functional block diagram showing processing and analysis that can be combined with the method described with reference to FIG.

FIG. 16 is a chart showing a sample of a beam intensity profile derived according to a preferred embodiment of the present invention.

FIG. 17 shows a profile of expected cure depth along two axes derived from beam profile information according to a preferred embodiment of the present invention.

FIG. 18 is a diagram illustrating a cross section of a cured mark of a photopolymerizable liquid cured by exposure to a beam.

FIG. 19 is a perspective view of a calibration plate.

FIG. 20 is a sectional view of a calibration plate.

FIG. 21 illustrates the main steps of the three-dimensional modeling process.

FIG. 22 is a software diagram of a three-dimensional printing system.

FIG. 23 is a diagram illustrating switches and indicators on a control panel.

FIG. 24: Sample of component record

FIG. 25: Sample of action curve

FIG. 26 is a diagram showing a recommended optical system.

FIG. 27 is a diagram showing a method of cleaning each element of the optical system shown in FIG. 26;

FIG. 28 illustrates replacement of an air filter.

FIG. 29 is a view showing components of a SLICE computer.

FIG. 30 is a diagram showing components of an electronic cabinet.

FIG. 31 is a diagram showing components of an electronic cabinet.

FIG. 32 is a view showing optical system components.

FIG. 33 is a diagram showing components of an optical system.

FIG. 34 is a diagram showing optical system components.

FIG. 35 shows the components of the chamber.

FIG. 36 is a diagram showing an arrangement of laser resonators;

FIG. 37 shows an alignment of the optical system.

FIG. 38 is a view showing an alignment in a chamber.

FIG. 39 is a diagram illustrating an SLA-1 type three-dimensional printing system;

FIG. 40 shows an assembly of an electronic cabinet.

FIG. 41 is a view showing an assembly of an optical apparatus.

FIG. 42 shows the assembly of the chamber.

FIG. 43 is an SLA-1 type wiring diagram

FIG. 44: Geometric model of a car that can be input to SLICE

FIG. 45 shows that all triangles included in the geometric model belong to one of three types: a plane triangle, a near-plane triangle, or a scanning triangle.

FIG. 46 shows how SLICE ranks triangles by type and height.

FIG. 47: SLIC scans triangle with smallest angle
Diagram showing how E ranks

FIG. 48 illustrates how SLICE stacks individual thin layers to represent a model and how to “skin-fill” triangles that are close to plane and plane triangles. Figure

FIG. 49 illustrates how individual thin layers are formed by skin-filling or hatching a region between boundaries.

FIG. 50 shows how SLICE creates a trapezoid for a triangle that is close to a plane.

FIG. 51 is a diagram showing why SLICE does not form a trapezoid for a plane triangle.

FIG. 52 illustrates how SLICE generates only a boundary for a scanning triangle (after which the boundary is hatched).

 ──────────────────────────────────────────────────続 き Continued on front page (31) Priority claim number 268,837 (32) Priority date November 8, 1988 (1988.11.8) (33) Priority claim country United States (US) (72) Inventor Stuart Thomas Spence California, United States, Sauss, Pasadena, Grand, Avenue, 333 (72) Inventor Harry Turnov California, United States, Van, Neuss, Sepulveda, Boulevard, 6025 (72) Inventor Thomas Olmquist, California, United States , San, Gabriel, Duart, Road, 9035 F-term (Reference) 2F065 AA52 AA53 BB05 FF44 GG04 HH04 JJ01 JJ18 JJ24 JJ26 LL22 LL30 LL49 LL62 MM16 QQ03 2G065 AA04 AA11 AB05 AB09 BA09 BB22 A08 BC09 WA25 WA97 WB01 WL02 WL13 WL44 WL67 WL92

Claims (12)

[Claims] 1. A working medium (22), which hardens upon exposure to a beam spot (27), continuously adjoins thin layers (30a-c) on a surface (23) of the working medium (22).
In a three-dimensional modeling device for modeling a three-dimensional object (30) from the working medium (22) by curing the working medium (22).
A beam profile measuring device for measuring an intensity profile of said beam spot (27), wherein said beam profile measuring device is disposed at a position fixed relative to said surface (23), and is selected in advance in said beam spot (27). The beam spot (27) is measured by measuring the intensities of a plurality of different regions each having a different size.
A beam profile measuring device comprising at least one sensor means (35; 116, 118) for measuring said intensity profile. 2. The at least one sensor means (3)
5; 116, 118) on the beam spot (27).
2. The beam profile measuring apparatus according to claim 1, further comprising scanning means for positioning said laser beam. 3. A working medium (22), which hardens upon exposure to a beam spot (27), continuously adjoins thin layers (30a-c) on a surface (23) of the working medium (22).
In a three-dimensional molding device for molding a three-dimensional object (30) from the working medium (22) by curing the working medium (22),
A beam profile measuring method for measuring an intensity profile of the beam spot (27), wherein the at least one sensor means (35; 11) is disposed at a position fixed relative to the surface (23).
6, 118) using the beam spot (27).
A beam profile measuring method, comprising: measuring the intensity profile of the beam spot (27) by measuring the intensity borne by each of a plurality of different partial regions having a preselected size within the region. 4. A method for determining a curing depth of a curing mark of the working medium (22) by the beam spot (27) using the beam profile measuring device according to claim 1. 5. The surface (2) of the working medium (22) using a beam profile measuring device according to claim 1.
3) A method of examining the degree of convergence of the beam spot (27) above. 6. A method for measuring the beam power of the beam spot (27) using the beam profile measuring device according to claim 1. 7. At least one sensor means (35; 116, 118) capable of detecting a beam spot (27).
An apparatus for determining a curing depth of a curing mark of the working medium (22) by the beam spot (27), comprising a beam profile measuring means including: 8. A step of obtaining an intensity profile of the beam spot (27), and the step of obtaining the beam spot (2) based on the intensity profile.
7) A method for determining the cure depth of the cure trace, comprising calculating the cure depth of the cure trace of the working medium (22) according to 7). 9. At least one sensor means (35; 116, 118) capable of detecting a beam spot (27).
An apparatus for examining the degree of convergence of the beam spot (27) on the surface (23) of the working medium (22), comprising a beam profile measuring means comprising: 10. Obtaining an intensity profile of the beam spot (27); and calculating a degree of convergence of the beam spot (27) on a surface (23) of the working medium (22) based on the intensity profile. Determining the degree of convergence at the surface (23), comprising: 11. At least one sensor means (35; 116, 11) capable of detecting a beam spot (27).
An apparatus for measuring the beam power of the beam spot (27), comprising a beam profile measuring means including (8). 12. A step of obtaining an intensity profile of a beam spot (27), and the step of obtaining the beam spot (2) based on the intensity profile.
7) A method for measuring the beam power, comprising the step of calculating the beam power.