Patent Application
20240110785
The invention relates to a light sensitive target and to an alignment system that includes the light sensitive target and at least one light emitting device, such as a laser emitter to produce a laser beam that impinges upon the target.
Laser alignment systems have been commercially available for decades and typically include at least one laser emitter that can emit a laser beam, at least one target that can identify the center of energy of the laser beam impinging upon the target and a data processor for receiving the data obtained by the target and presenting that data to an operator in a meaningful and usable form. This combination of a laser emitter, a target and a processor can be used to identify x, y coordinates of the target relative to the laser emitter.
The known laser emitter and/or the known target can be used with a collimating lens to produce a collimated laser beam. The collimated laser beam can be used to identify the angular alignment of the laser beam relative to the target.
U.S. Pat. No. 4,483,618 describes a target that employs a virtual target location. In particular, a pentaprism is mounted in the path of the incoming laser beam. The reflective surface of the pentaprism is disposed at a specified distance in front of a desired measurement point. The photoelectric cell of the target is disposed at that same distance from the reflective surface of the pentaprism but at a position to be impinged upon by the reflected laser beam. The actual photoelectric cell provides the same readings as readings that would be produced by a virtual target at the desired measurement point. Targets that incorporate this concept enable measurements to be taken at a desired measurement point even though the actual photoelectric cell cannot physically be placed at that point.
Some laser alignment systems have a rotating pentaprism associated with the laser emitter. The pentaprism reflects the incoming laser beam 90°, and the rotation of the pentaprism causes the reflected laser beam to sweep a flat optical plane. One or more targets can be positioned to be impinged upon the laser beam that is being swept through the flat optical plane to identify positions of the one or more targets relative to the plane.
The above-described laser alignment components and systems generally work very well and can provide high precision readings relating to the position of the target relative to the incoming laser beam with respect to x, y coordinates, to identify the angular alignment of the target relative to the incoming laser beam and to identify the position of the target relative to a flat optical plane. However, an ability to perform all of these measurements generally has required at least two different types of targets. Furthermore, obtaining accurate measurements is more difficult if the target is not aligned properly with respect to the incoming laser beam. For example, the target illustrated schematically in the above-referenced U.S. Pat. No. 4,483,618 would require the target to be fixtured fairly close to the desired position and alignment, and this known target would require calculations to be carried out to compensate for any misalignment or incorrect positioning of the target relative to the incoming laser beam. Additionally, the collimating lens that is required to make angular alignment measurements has required a complicated mounting arrangement with a possibility of inaccurate positioning and repeatability problems. Furthermore, the target described in U.S. Pat. No. 4,483,618 is not well suited for use with a with a laser emitter that sweeps a flat optical plane to determine the position of that target relative to the flat optical plane.
An object of this invention is to provide an enhanced target that can be used for measuring displacement of the target relative to the incoming laser beam, for determining the alignment of the target to the incoming laser beam and for determining the position of the target relative to a flat optical plane.
This disclosure relates to a target assembly with a housing having opposite front and rear faces. A face plate is mounted to the rear face of the target housing and has a rear surface that defines a measurement plane at which measurements can be made. A mounting stud is mounted to project rearward from the rear surface of the face plate and can be mounted in an apparatus, such as a chuck or spindle.
The front face of the target housing includes an aperture through which a laser beam can be directed.
The target assembly further has a lens assembly. The lens assembly includes a lens housing with a mounting face that can be mounted removably against the front face of the target housing. For example, magnets are provided in some embodiments to enable removable mounting of the lens assembly to the front face of the target housing. A collimating lens is mounted in the lens housing of some embodiments.
A right angle prism is mounted in the target housing at a position to align with the optical axis of the collimating lens when the lens assembly is mounted properly on the target housing. The right angle prism has a reflecting surface aligned at a 45° angle to the optical axis of the collimating lens. Additionally, a sensor cell is mounted in the target housing so that the plane of the sensing surface of the sensor cell is parallel to the optical axis of the lens and perpendicular to the rear surface of the face plate of the target housing. A distance from the point where the optical axis intersects the reflecting surface of the right angle prism to the sensor cell is equal to a distance from the point where the optical axis intersects the reflecting surface of the right angle prism to the rear surface of the face plate. The rear surface of the face plate defines the measurement plane at which measurements will be made. Thus, readings obtained by the sensor cell are exactly the same as readings that would be made if the surface of the sensor cell was coplanar with the measurement plane defined by the rear surface of the face plate.
The target housing of some embodiments includes a rechargeable battery that can provide sufficient power to operate the sensor cell. The target housing of some embodiments further may include a Bluetooth apparatus that enables readings obtained by the sensor cell to be communicated wirelessly with a data processing unit that is external of the target housing. The Bluetooth apparatus may be powered by the rechargeable battery.
The target assembly that has the collimating lens assembly mounted to the front surface of the target housing can be used with a laser emitter to identify angular alignment of an incoming laser beam from the laser emitter to the measurement plane at the rear of the face plate. The target assembly can also can be used with the laser emitter to identify horizontal and vertical displacements of the laser beam by removing the collimating lens assembly from the front surface of the target housing. These reading also are the same as those that would be obtained if the sensor cell was located at the rear surface of the face plate.
The target assembly also can be used for flatness measurements relative to a plane. In this regard, a measuring base can be mounted on a frame of reference in proximity to the optical plane that will be swept e.g. by a rotating pentaprism. The base may include a mounting plate with an aperture that is dimensioned to receive the mounting stud of the target assembly. The above-described lens assembly can be removed from the target housing. The laser beam that sweeps a flat optical plane will sweep across the right angle prism in the target housing and will be reflected to the sensor cell to define the position of the desired measurement point relative to the optical plane produced by the laser.
These and other aspects of this disclosure will become more apparent from accompanying drawings and the description of those drawings.
A target assembly in accordance with an embodiment of the invention is identified by the numeral 10 in
The front face 14 of the target housing 12 includes an aperture 24, as shown in
The mounting face 30 of the lens housing 28 has an alignment hole 33 and two alignment balls 34a and 34b. The mounting face 30 of the lens housing 28 also has three permanent magnets 37 spaced circumferentially around the mounting face 30 at an angular spacing of 120°. The front face 14 of the target housing 12 includes an alignment pin 13 disposed to engage in the alignment hole 33 of the lens housing 28, two alignment recesses 14a and 14b disposed and dimensioned to receive the two alignment balls 34a and 34b on the lens housing 28 and three permanent magnets 17 disposed to align with the permanent magnets 37 on the lens housing 28 when the lens housing 28 is aligned properly on the target housing 12. A projecting distance of the alignment pin 13 of this embodiment exceeds a projecting distance of the alignment balls 34a and 34b on the lens housing 28. Thus, the alignment pin 13 of the target housing 12 can be inserted into the alignment hole 33 of the lens housing 28, and the lens housing 28 then can be rotated about the alignment pin 13 until the alignment balls 34a, 34b of the lens housing 28 align respectively with the alignment recesses 14a, 14b of the target housing 12. The magnets 37 also will align with one another at this rotational position of the lens housing 28 with the target housing 12 and will urge the lens housing 28 toward the target housing 12. Thus, the two alignment balls 34a, 34b on the lens housing 28 will engage respectively with the two alignment recesses 14a and 14b on the front face 14 of the target housing 12 and will be held in position by the opposed magnets 17, 37 to ensure that the lens assembly 26 is retained removably and is aligned properly on the target housing 12 vertically, horizontally and rotationally.
A right angle prism 44 is mounted in the target housing 12 at a position to align with the optical axis X of the collimating lens 32 when the lens assembly 26 is mounted properly on the target housing 12, as shown in
The target housing 12 further includes a rechargeable battery 50 that provides sufficient power to operate the sensor cell 48. A charger input port 51 is connected to the rechargeable battery 50 and is accessible from the exterior of the target housing 12 to receive, for example, a USB port for charging the battery 50. The input port 51 also can be used for cabled data transfer. The target housing 12 further includes a Bluetooth radio 52 that communicates with the sensor cell 48 and enables readings obtained by the sensor cell 48 to be communicated wirelessly with the data processing unit or control unit 53 external of the target housing 12, as shown schematically in
In the context of this disclosure, a “control unit” can be understood to include, for example, a processor and/or a storage unit or memory for storing algorithms and program commands. By way of example, the processor and/or the control unit is specifically configured to carry out program commands in such a way that the processor and/or the control unit carries out functions to implement or realize a method as disclosed herein or a step of a method as disclosed herein. The term control unit is used here synonymously with devices known from the prior art. A control unit, therefore, encompasses a “computer” and accordingly comprises one or more general-purpose processors (CPUs) or microprocessors, RISC processors, GPUs and/or DSPs. The control unit or computer has for example additional elements such as storage interfaces or communication interfaces such as a keyboard and/or a touch screen monitor. Optionally or additionally, the terms “control unit” and “computer” refer to a device that is capable of executing a provided or included program, preferably with standardized programming language (for example C++, JavaScript or Python), and/or of controlling and/or accessing data storage devices and/or other devices such as input interfaces and output interfaces. The term computer also refers to a multiplicity of processors or a multiplicity of (sub)computers that are interconnected and/or connected and/or otherwise communicatively connected and possibly share one or more other resources, such as for example a memory.
In the context of this disclosure, a “storage unit” can be understood to mean, for example, a volatile memory in the form of random access memory (RAM) or a permanent memory such as a hard disk drive or a data medium or, for example, a replaceable storage module or a cloud-based storage solution.
The target assembly 10 can be used with a laser emitter 54 to identify angular alignment of an incoming laser beam 56 from the laser emitter 54 to the measurement plane at the rear of the face plate 18. In this regard, the lens assembly 26 is mounted to the front surface 14 of the target housing 12 by relying upon the alignment balls 34a, 34b on the mounting face 30 of the lens housing 28, the alignment recesses 14a, 14b on the front face 14 of the target housing 12 and the opposed pairs of magnets 17, 37 to align and retain the lens assembly 26 in a proper position on the front face 14 of the target housing 12. The collimating lens 32 produces a collimated laser beam 56 that is reflected off the surface 46 of the right angle prism 44 and impinges upon the sensor cell 48. The center of energy of the reflected laser beam 56 impinging upon the sensor cell 46 is transmitted by the Bluetooth apparatus to the external control unit 53 to provide highly accurate information regarding the angular alignment of the measurement plane at the rear surface 20 of the face plate 18 relative to axis of the laser beam 56.
The target assembly 10 also can be used with the laser emitter 54 to identify horizontal and vertical displacement of the laser beam relative to the axis of the machine tool or other apparatus that is being aligned. For this purpose, the lens assembly 26 is removed from the front surface 14 of the target housing 12 merely by exerting sufficient force to overcome the attraction between the magnets 37 in the lens housing 28 and the corresponding magnets 17 on the front surface 14 of the target housing 12. The laser beam 54 again is reflected from the reflective surface 46 of the right angle prism 44 and impinges upon the sensor cell 46. These readings obtained without the collimating lens assembly 26 will identify horizontal and vertical positions of the laser beam 54 relative to the target assembly 10. These readings are the same as those that would be obtained if the sensor cell 46 was located at the rear surface 20 of the face plate 18.
As noted above, laser alignment systems can be used to determine the location of one or more points to a plane. Laser alignment systems used for this purpose could have a rotating pentaprism that receives an incoming laser beam and effectively sweeps a plane with the reflection generated by the rotating pentaprism. Examples of laser devices for sweeping one or more flat optical planes are shown and described in U.S. Pat. Nos. 6,038,050 and 6,292,303, the disclosures of which are incorporated herein by reference. Targets would be located at one or more positions and readings obtained by those targets would determine the relationship between the measurement points and the optical plane that is swept by the rotating pentaprism. Prior art targets that were used to measure horizontal and vertical displacements of two parts of a machine relative to a rotational axis of the machine and/or to measure the alignment of rotatable components relative to a rotational axis generally were not well suited for determining the positions of locations relative to a plane. Accordingly, two different types of targets generally would be purchased for these different types of measurements.
The target assembly 10 described and illustrated herein also can be used for flatness measurements relative to a plane. In this regard, a measuring base 60, as shown in
A target mount 80 is mounted for vertical and rotational adjustments relative to the body 66 of the mounting bracket 64. More particularly, a lower surface of the target mount 80 has a post 82 that is mounted in the aperture 70 extending vertically through the body 66 of the mounting bracket 64 so that the target mount 80 can be rotated about the vertical axis of the post 82 relative to the body 66 of the mounting bracket 64. Additionally, the post 82 enables the target mount 80 to be moved vertically relative to the body 66 of the mounting bracket 64. The bolts 72 can be tightened for holding the target mount 80 in a fixed rotational position and a fixed vertical position relative to the mounting bracket 64. The target mount 80 includes a horizontal supporting surface 82 for supporting a lower surface of the target assembly 10 and a vertical support 84 for supporting the rear surface 20 of the faceplate 18 of the target assembly 10. More particularly, the vertical support 84 has an aperture 86 extending therethrough for receiving the mounting stud 22 of the target assembly 10. A bolt 88 can be threaded into the aperture 23 in the mounting stud 22 of the target assembly 10 for securing the target assembly 10 on the vertical support 84 of the target mount 80. The position of the aperture 24 in the front surface 14 of the target assembly 10 can be adjusted vertically and rotationally by making corresponding vertical and rotational movements of the target mount 80 relative to the mounting bracket 64 to enable a laser beam from a remote location to pass through the aperture 24 in the front surface 14 of the target assembly 10 and to be reflected by the right angle prism 44 toward the sensing cell 46.
The invention has been described with respect to a preferred embodiment. However, changes can be made without departing from the scope of the invention.
This application claims the benefit of U.S. Provisional Patent application No. 63/411,316 filed Sep. 29, 2022, the disclosure of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63411316 | Sep 2022 | US |
