Laser interferometry system and method

Abstract

The present invention provides a system and method for measuring a moving object using laser interferometry. The provided system includes a laser interferometry system, which includes: a laser transmitter, which is configured to emit a laser beam; a beam splitter, which is configured to split the emitted laser beam into a first beam split and a second beam split directed to a deflector, wherein the first beam split includes a first beam diameter and a second beam diameter, the first beam diameter is larger than the second beam diameter, and the second beam split includes a third beam diameter and a fourth beam diameter, the third beam diameter is larger than the fourth beam diameter; and a deflector, which is configured to deflect the first beam split to intersect with the second beam split, wherein the first beam diameter is parallel to the third beam diameter.

Description

[0001] CROSS REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 903,310, filed on September 20, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to methods of measuring moving objects using laser interferometry, and more particularly, to methods of obtaining reliable and accurate measurements of moving objects using laser interferometry. Background Art

[0004] Laser interferometry can be used to measure the speed or length of a moving object. Laser interferometry uses two laser beams that converge at the surface of the moving object to form an intersection area. The moving object reflects light within the intersection area (or depth of field). This reflected light is detected by a light detector and the speed and / or length of the moving object can be determined using the Doppler effect. Accurate measurements may rely on one or more of the following properties: object color, object texture, presentation angle, object reflectivity or absorption properties, cleanliness of the laser path between the laser surface velocimeter and the object, object composition, etc.

[0005] A laser surface velocimeter is an instrument that measures the velocity of a moving object using the Doppler shift of a laser beam (i.e., reflected light from the surface of the moving object). Specifically, a laser surface velocimeter intersects two collimated, monochromatic, and coherent laser beams at the moving object to be measured. Transmission optics direct the beams to intersect at a defined distance, where the two beams interfere and produce a set of fringes. As the moving object passes through the fringes, it reflects light, which is then collected by receiving optics and focused on a photodetector. Summary of the invention

[0006] Laser interferometry systems and methods are provided for measuring moving objects using laser interferometry. The systems and methods provided herein can measure various characteristics of a moving object, such as its velocity. To obtain more accurate measurements, the systems and methods provided herein can include an effective measurement area that is larger than the effective measurement area of ​​the conventional laser interferometry systems and methods described above. Specifically, the larger effective measurement area can be achieved by rotating the orientation of an elliptical laser beam profile, by extending one or more axes of the elliptical profile, and / or by using a smaller convergence angle.

[0007] The conventional methods described above using laser interferometry are particularly inadequate in capturing accurate measurements of moving objects with small cross-sectional areas. Because such objects have very little reflective area to produce a good measurement (e.g., the crown of an object with a circular cross-sectional area), the precise position of the laser is critical to achieving an accurate measurement. As a result, it is often difficult to receive enough light reflected back from a moving object to obtain an accurate measurement. In particular, objects with small cross-sectional areas, objects that change position rapidly (in directions other than the direction of velocity), and objects that cannot be guided due to the nature of the manufacturing process are often difficult to measure accurately using conventional laser interferometry.

[0008] Disclosed herein are methods for accurately measuring such objects (e.g., objects with small cross-sectional areas, objects that change position rapidly, and objects that cannot be guided due to the nature of the manufacturing process). Specifically, the methods provided herein include: (1) rotating the laser to increase the effective measurement area; (2) expanding the laser beam along one or more axes; and (3) minimizing the convergence angle to obtain a longer depth of field. Each of these features will be described in detail below.

[0009] In some embodiments, a laser interferometry system is provided, the system comprising: a laser emitter configured to emit a laser beam; a beam splitter configured to split the emitted laser beam into a first beam and a second beam directed toward a deflector, wherein the first beam comprises a first beam diameter and a second beam diameter, the first beam diameter is larger than the second beam diameter, and the second beam comprises a third beam diameter and a fourth beam diameter, the third beam diameter is larger than the fourth beam diameter; and a deflector configured to deflect the first beam to intersect with the second beam, wherein the first beam diameter is parallel to the third beam diameter.

[0010] In some embodiments of the system, the first beam diameter is equal to the third beam diameter and the second beam diameter is equal to the fourth beam diameter.

[0011] In some embodiments of the system, the first beam segment intersects the second beam segment at an angle of less than 60 degrees.

[0012] In some embodiments of the system, the transmit laser beam includes a fifth beam diameter and a sixth beam diameter, the fifth beam diameter is greater than the sixth beam diameter, and at least one of the fifth beam diameter or the sixth beam diameter is increased by passing the transmit laser beam through a cylindrical lens.

[0013] In some embodiments of the system, the first beam diameter is at least three times the second beam diameter, and the third beam diameter is at least three times the fourth beam diameter.

[0014] In some embodiments of the system, the system includes a processor, a memory, and instructions stored on the memory, the instructions configured to cause the system to calculate a speed at which an object moves through an intersection area.

[0015] In some embodiments of the system, the calculation speed is in a direction orthogonal to the first beam diameter and the third beam diameter.

[0016] In some embodiments of the system, the object comprises a rope, a wire, a rod, or a flat piece of paper or plastic.

[0017] In some embodiments, a laser interferometry system is provided, the system comprising: a laser emitter configured to emit a laser beam; a beam splitter configured to split the emitted laser beam into a first beam and a second beam directed toward a deflector, wherein the first beam comprises a first beam diameter and a second beam diameter, the first beam diameter is larger than the second beam diameter, and the second beam comprises a third beam diameter and a fourth beam diameter, the third beam diameter is larger than the fourth beam diameter; and a deflector configured to deflect the first beam to intersect with the second beam, wherein the emitted laser beam comprises a fifth beam diameter and a sixth beam diameter, the fifth beam diameter is larger than the sixth beam diameter, and at least one of the fifth beam diameter or the sixth beam diameter is increased by passing the emitted laser beam through a cylindrical lens.

[0018] In some embodiments of the system, the first beam diameter is parallel to the third beam diameter.

[0019] In some embodiments of the system, the first beam diameter is equal to the third beam diameter and the second beam diameter is equal to the fourth beam diameter.

[0020] In some embodiments of the system, the first beam segment intersects the second beam segment at an angle of less than 60 degrees.

[0021] In some embodiments of the system, the first beam diameter is at least three times the second beam diameter, and the third beam diameter is at least three times the fourth beam diameter.

[0022] In some embodiments of the system, the system includes a processor, a memory, and instructions stored on the memory, the instructions configured to cause the system to calculate a speed at which an object moves through an intersection area.

[0023] In some embodiments of the system, the calculation speed is in a direction orthogonal to the first beam diameter and the third beam diameter.

[0024] In some embodiments of the system, the object comprises a rope, a wire, a rod, or a flat piece of paper or plastic.

[0025] In some embodiments, a laser interferometry system is provided, the system comprising: a laser emitter configured to emit a laser beam; a beam splitter configured to split the emitted laser beam into a first beam and a second beam directed toward a deflector, wherein the first beam comprises a first beam diameter and a second beam diameter, the first beam diameter is larger than the second beam diameter, and the second beam comprises a third beam diameter and a fourth beam diameter, the third beam diameter is larger than the fourth beam diameter; and a deflector configured to deflect the first beam to intersect with the second beam, wherein the first beam intersects with the second beam at an angle less than 60 degrees.

[0026] In some embodiments of the system, the first beam diameter is equal to the third beam diameter and the second beam diameter is equal to the fourth beam diameter.

[0027] In some embodiments of the system, the first beam segment intersects the second beam segment at an angle of less than 20 degrees.

[0028] In some embodiments of the system, the first beam diameter is parallel to the third beam diameter.

[0029] In some embodiments of the system, the transmit laser beam includes a fifth beam diameter and a sixth beam diameter, the fifth beam diameter is larger than the sixth beam diameter, and at least one of the fifth beam diameter or the sixth beam diameter is increased by passing the transmit laser beam through a cylindrical lens.

[0030] In some embodiments of the system, the first beam diameter is at least three times the second beam diameter, and the third beam diameter is at least three times the fourth beam diameter.

[0031] In some embodiments of the system, the system includes a processor, a memory, and instructions stored on the memory, the instructions configured to cause the system to calculate a speed at which an object moves through an intersection area.

[0032] In some embodiments of the system, the calculation speed is in a direction orthogonal to the first beam diameter and the third beam diameter.

[0033] In some embodiments of the system, the object comprises a rope, a wire, a rod, or a flat piece of paper or plastic. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Various embodiments are described with reference to the accompanying drawings, in which:

[0035] Figure 1A and 1B each depicts a laser beam reflected from a moving object according to some embodiments;

[0036] Figure 2A and 2B each depicts a schematic diagram of a laser beam orientation for measuring a moving object according to some embodiments;

[0037] Figure 3 shows a top view of a laser surface velocimeter according to some embodiments;

[0038] Figure 4 Demonstrating features of a laser surface velocimeter according to some embodiments;

[0039] Figure 5 Demonstrating features of a laser surface velocimeter according to some embodiments;

[0040] Figure 6 showing laser beam configurations according to some embodiments;

[0041] Figure 7 showing a converging laser beam producing a fringe pattern according to some embodiments; and

[0042] Fig. 8A and 8B Each depicts a stripe pattern according to some embodiments. DETAILED DESCRIPTION

[0043] Laser interferometry systems and methods are described herein for measuring moving objects using laser interferometry. Specifically, the methods described herein are used to obtain more reliable and accurate measurements of such objects. For example, measurements that can be obtained using the systems and methods described herein can include measurements related to the movement of such moving objects for process control, speed monitoring, cut length control and verification, and thickness control.

[0044] Laser interferometry obtains measurements by using a beam splitter to split laser energy into two beams. The split beams are then recombined or intersected. The light reflected by the object in the area where the split beams intersect (called the depth of field) is measured. Accurate measurements may depend on one or more of the following properties: object color, object texture, angle of presentation, object reflectivity or absorptive properties, cleanliness of the laser path between the laser surface velocimeter and the object, and object composition.

[0045] Conventional methods of measuring moving objects have difficulty obtaining reliable and accurate measurements due to small reflective areas on the surface of the object. In addition, these methods are designed so that the laser surface velocimeter is stationary and measures the speed of the moving object in the X-axis. However, even if the object moves in the X-axis, the position of the moving object will continue to fluctuate in the Y and Z-axis directions. Therefore, this small reflective area plus the object moving in the Y and Z axes can lead to inaccurate, unreliable or lack of measurement.

[0046] Figure 1A and 1B The two figures illustrate the difficulty of measuring moving objects using conventional methods. The two figures show a cross section of an object 102 traveling in a direction extending into and out of the page. Figure 1A , a laser beam 104 is directed directly onto the crown of object 102, so that reflected or scattered light 106 is directed back along the path of laser beam 104. Figure 1B The object 102 is shown to have been moved slightly to the left so that the laser beam 104 is not directed onto the crown of the object 102, but rather onto the side of the object 102. Therefore, the reflected or scattered light 106 is directed out at an angle that does not intersect the path of the laser beam 104. Therefore, assuming that the scattered light 106 needs to be directed back in the direction of the laser beam 104 to be detected by the detector, Figure 1B The scattered light 106 cannot be received / detected to obtain accurate measurement. Therefore, even a slight movement of the object 102 will prevent the laser surface velocimeter from obtaining reliable and accurate measurement.

[0047] Figure 2A and 2B It also shows how conventional laser surface velocimeters, and in particular, the effective measurement area of ​​conventional laser surface velocimeters, are unreliable. In particular, Figure 2A A moving object 204 is shown configured to move linearly in the X-axis direction (e.g., left or right). Laser beam profile 202A depicts a laser beam profile consistent with the systems and methods described herein. Laser beam profile 202B depicts a non-rotating laser beam profile consistent with a conventional measurement system. When the moving object 204 is centered relative to laser beam profiles 202A and 202B, both the conventional system (i.e., laser beam profile 202B) and the system described herein (i.e., laser beam profile 202A) can obtain accurate measurements.

[0048] However, Figure 2BThe difficulty that arises when using conventional measurement methods is shown. As shown, the moving object has shifted slightly in the Y-axis direction, so that it is not completely centered relative to the laser beam profiles 202A and 202B. Therefore, the conventional measurement method (i.e., laser beam profile 202B) cannot account for this shift and obtain an accurate measurement. However, the systems and methods provided herein (i.e., laser beam profile 202A) are more capable of obtaining an accurate measurement because the laser beam profile 202A is still directed to the crown of the moving object 204 even though the object is shifted.

[0049] The systems and methods described herein include a larger intersection or effective measurement area (i.e., where two laser beams intersect) that can allow for more reliable and accurate measurement of moving objects. The systems and methods described herein utilize a laser surface velocimeter for measurement. Where it can be implemented to form a larger effective measurement area, specific features of the systems and methods include: (1) rotating the laser beam profile; (2) expanding the laser beam on one or more axes; and (3) producing a longer depth of field. In addition to a detailed description of each of the above features of the measurement methods described herein, a description of a laser surface velocimeter for use with the systems and methods provided herein is provided below.

[0050] Laser surface velocimeter

[0051] In addition to methods for measuring moving objects, also provided herein is a laser surface velocimeter (ie, a laser interferometry system) that can be used with the measurement methods provided herein. A description of a laser surface velocimeter is provided below.

[0052] Figure 3 A top view configuration of a laser surface velocimeter 300 according to some embodiments provided herein is provided. As shown in the figure, the laser surface velocimeter 300 can include a laser diode 302, a collimating lens 304, an emission laser beam 306, a cylindrical lens 308, a beam splitter 310, a transmission laser beam 312, a deflection laser beam 314, and a mirror 316.

[0053] In some embodiments, the laser diode 302 can be rotated relative to the laser diode of a conventional laser surface velocimeter to produce a rotated laser beam profile. Figure 4 Shown is a conventional laser beam diode 402, a conventional laser beam profile 404, and a moving object 406. In this conventional configuration, the length of the laser beam profile 404 is parallel to the direction of movement of the moving object 406.

[0054] In comparison, Figure 5A configuration of a laser surface velocimeter 500 is shown according to some embodiments. The laser surface velocimeter 500 may include a laser diode 502, a laser beam profile 504, and a moving object 506. A cylindrical lens 508 may also be included to expand the length or width of the laser beam profile 504, as described in more detail below.

[0055] like Figure 5 As shown in FIG. 5 , the laser diode 502 is Figure 4 The laser diode 402 is rotated 90 degrees. The laser beam profile 504 is rotated by rotating the laser diode 502. By rotating the laser diode 502 to generate the rotated laser beam profile 504, the effective measurement area of ​​the laser beam can be increased.

[0056] Figure 3 The laser surface velocimeter 300 also includes a collimating lens 304. The collimating lens 304 is an optical lens that helps to narrow the laser beam and / or collimate the beam as desired.

[0057] In some embodiments, the laser surface velocimeter 300 may also include a cylindrical lens 308 (or any other means for expanding the diameter of the laser beam). Figure 3 The cylindrical lens 308 of the cylindrical lens is a lens that can expand or compress light in one or more directions. In some embodiments, the cylindrical lens 308 can be used to expand the laser beam profile 304 in a specific direction. For example, the cylindrical lens 308 can be used to expand the laser beam profile 304 in the direction along the Y axis. More details related to cylindrical lenses and expansion of laser beam profiles will be provided below.

[0058] In some embodiments, the laser surface velocimeter 300 may include a beam splitter 310. A beam splitter is an optical device that can split a beam of light into two beams. Figure 3 , the beam splitter 310 can split the collimated laser beam 306 into two separate laser beams: a transmission laser beam 312 and a deflection laser beam 314. In some embodiments, the transmission laser beam 312 and the deflection laser beam 314 can diverge from the beam splitter 310 at an angle of 30 to 90 degrees. In some embodiments, the size and / or shape of the cross-section of the transmission laser beam 312 and the deflection laser beam 314 can be the same.

[0059] In some embodiments, the laser surface velocimeter 300 may include a reflector 316. The reflector 316 may be used to deflect the deflected laser beam 314. In particular, the reflector 316 may be configured to deflect the deflected laser beam 314 so that the transmission laser beam 312 and the deflected laser beam 314 converge at the surface of the moving object. In some embodiments, the laser surface velocimeter 300 may include two reflectors 316: one for redirecting the deflected laser beam 314 and the other for redirecting the transmission laser beam 312. In some embodiments, the reflector 316 may redirect the transmission laser beam 312 and / or the deflected laser beam 314 so that the two laser beams converge downstream. In some embodiments, the transmission laser beam 312 and the deflected laser beam 314 may converge at the location of the object to be measured, such as the surface of a moving object. In some embodiments, the laser surface velocimeter 300 may include a polarizer.

[0060] Rotating laser

[0061] The following describes a system and method for measuring a moving object including a laser beam profile that is rotated compared to the laser beam profile of a conventional measurement method. For example, a laser emitter may be rotated so that the laser beam profile of the emitted laser beam is oriented so that its length is orthogonal to the direction of travel of the moving object. (The length of the laser beam profile is greater than the width of the laser beam profile). As used herein, the term "profile" with respect to a laser beam (e.g., a laser beam profile) refers to the cross-sectional area of ​​the laser beam that is in the same plane as the diameter of the beam, where the diameter is perpendicular to the beam axis of the laser beam.

[0062] A beam of light (eg, a laser beam) may be defined by a beam axis, a first beam diameter (BD1), and a second beam diameter (BD2). As used herein, BD1 and BD2 are perpendicular to the beam axis of the beam of light, and BD1 and BD2 are perpendicular to each other.

[0063] In some embodiments, rotating the laser beam profile can produce a larger effective measurement area (i.e., the area where the transmitted beam and the deflected beam intersect at the surface of the moving object). In some embodiments, the shape of the laser beam profile can be elliptical. In some embodiments, the laser beam can be rotated so that the major axis of the ellipse of the elliptical profile (i.e., BD1 or BD2 of the beam) is orthogonal to the direction of travel of the moving object to be measured.

[0064] Figure 6Depicted is a configuration 600 including a laser beam profile 602 that has been rotated so that the major axis (BD1) of the elliptical profile is perpendicular to the direction of object movement. The laser beam profile 602 is shown as having a major axis (BD1) in the vertical direction (Y-axis) and a minor axis (BD2) in the horizontal direction (X-axis). A moving object 604 is shown as having a length in the horizontal direction (X-axis) and movement in the horizontal direction (X-axis). Thus, the rotated laser produces a beam profile 602 having a major axis (BD1) that is perpendicular to the movement of the moving object 604.

[0065] Expanding the laser beam profile

[0066] The method for measuring a moving object provided herein may include expanding the profile of the laser beam along one or more beam diameters. In some embodiments, the expansion of the laser beam profile is achieved by using a cylindrical lens.

[0067] The enlargement of the laser beam profile can be achieved without degrading the quality of the collimated light received from the laser. If the quality of the collimated light is degraded, it will compromise the accuracy consistency over the full depth of the laser surface velocimeter.

[0068] In some embodiments, the expansion of the laser beam profile does not compromise the accuracy of measurements obtained using the laser surface velocimeter. In particular, if performed properly, the expansion of the profile does not change the fringe pattern in the depth of field (compared to the original non-expanded laser beam profile).

[0069] In some embodiments, the laser beam profile can be expanded from 1.5 times to 10 times or from 2 times to 5 times its original length. In some embodiments, the laser beam profile can be expanded to more than 1.5 times, more than 2 times, more than 3 times, more than 4 times, more than 5 times, or more than 6 times its original length. In some embodiments, the laser beam profile can be expanded to less than 10 times, less than 8 times, less than 6 times, less than 5 times, less than 4 times, or less than 3 times its original length. In some embodiments, the laser beam profile can be expanded in a single dimension. In some embodiments, the laser beam profile can be expanded in more than one dimension.

[0070] Figure 5 A laser surface velocimeter 500 is shown including an expanded laser beam profile according to some embodiments. As described above, the laser surface velocimeter 500 may include a laser diode 502, a laser beam profile 504, a moving object 506, and a cylindrical lens 508.

[0071] The laser diode 502 may be rotated, as described in detail above, or the laser diode 502 may be configured to emit a laser beam consistent with the prior art (and not rotated).

[0072] like Figure 5As shown, the moving object 506 can have a velocity direction that is horizontal or along the X-axis. Thus, to prevent damage to the accuracy of the measurement, the laser beam profile 504 can be expanded in the Y dimension and / or in the Z dimension. In some embodiments, a cylindrical lens 508 can be used to expand the laser beam profile 504 in one or more dimensions. For example, as Figure 5 shown, the cylindrical lens 508 expands the laser beam profile 504 at least in the vertical direction or along the Y-axis.

[0073] Depth of field

[0074] In some embodiments, the method of measuring a moving object provided herein can include a longer depth of field. In some embodiments, the depth of field can be expanded in a direction that is different from the velocity direction of the material to be measured. For example, if the material to be measured has a velocity direction along the X-axis, then the depth of field can be expanded in the Y-axis and / or in the Z-axis. As used herein, "depth of field" and "effective measurement region" (or "measurement region") can be used interchangeably. This region (i.e., depth of field, effective measurement region, or measurement region) is produced when the transmitted laser beam and the deflected laser beam partially or fully converge and intersect.

[0075] In the depth of field, a fringe pattern is produced. For example, the light waves of the transmitted laser beam interfere with the light waves of the deflected laser beam to produce interference fringes (e.g., alternating bright and dark bands). This redistribution of light intensity produces an interference pattern. When these interference patterns are reflected from the surface of a material (e.g., the material to be measured), the reflected light produces high and low intensity levels. These different levels are reflected into the laser surface velocimeter and used to measure characteristics and more specifically, the movement of the material. For example, the reflected energy can be received by the laser surface velocimeter and directed onto a photodiode. The photodiode converts the energy from light energy to electrical energy. The electrical energy is also referred to as a Doppler signal because its frequency changes with the velocity of the material from which the laser energy is reflected. This Doppler signal is converted to velocity based on a known calibrated fringe pattern geometry and compared with the time between electrical cross patterns received by the laser surface velocimeter.

[0076] Figure 7 A schematic diagram showing a converging laser beam is presented. As shown, the laser beam 720 and the laser beam 722 converge and intersect, thereby producing a depth of field / effective measurement region 724. This depth of field / effective measurement region 724 includes a fringe pattern produced by the intersecting laser beams at the convergence point. In some embodiments, the object or material to be measured is positioned within the depth of field / effective measurement region 724. As shown in the figure, the laser beam profile rotates Figure 5 in unison with the laser beam profile 502.

[0077] Fig. 8A and 8B each show a fringe pattern produced by intersecting two laser beams. In Fig. 8AIn the embodiment, laser beam 820 and laser beam 822 are larger than Figure 8B The angle of convergence represented by the convergence angle is convergent. Fig. 8A As shown in FIG. 1 , a large crossover (i.e., convergence) angle produces a smaller fringe pattern or a shorter depth of field. Conversely, Figure 8B Smaller crossover (ie, convergence) angles are shown, which produce larger fringe patterns or longer depth of field.

[0078] In some embodiments, the depth of field may be expanded to accommodate the reduced depth of field produced by rotating the laser beam profile and / or by expanding the laser beam profile. For example, rotating the laser beam profile as described above may reduce the depth of field due to a vertical laser beam profile (e.g., Figure 5 The laser beam profile 504) rather than the horizontal laser beam profile of the prior art (eg Figure 4 The laser beam profile 404) reduces the intersection range on the Z axis.

[0079] In some embodiments, to accommodate this shorter depth of field produced by the rotated laser beam profile, a smaller angle may be used between the two laser beams to recover at least a portion of the depth that would otherwise be lost due to the rotation of the laser beam profile. For example, a smaller angle between the two laser beams may be achieved to minimize the distance between the transmitted laser beam and the deflected laser beam (e.g., Figure 3 The distance between the transmitted laser beam 312 and the deflected laser beam 314 is minimized. Minimizing this distance between the transmitted and deflected laser beams can minimize the convergence angle of the two laser beams.

[0080] In some embodiments, the convergence angle of the transmission laser beam and the deflection laser beam may be from 5 to 40 degrees or from 10 to 30 degrees. In some embodiments, the convergence angle of the transmission laser beam and the deflection laser beam may be greater than 5 degrees, greater than 10 degrees, greater than 15 degrees, greater than 20 degrees, greater than 25 degrees, or greater than 30 degrees. In some embodiments, the convergence angle of the transmission laser beam and the deflection laser beam may be less than 40 degrees, less than 35 degrees, less than 30 degrees, less than 25 degrees, less than 20 degrees, less than 15 degrees, or less than 10 degrees.

[0081] Unless otherwise defined, all technical terms, symbols, and other technical terms or nouns used herein are intended to have the same meaning as commonly understood by those of ordinary skill in the art to which the claimed subject matter belongs. In some cases, terms with commonly understood meanings are defined herein for clarity and / or for ease of reference, and the inclusion of such definitions herein is not necessarily to be construed as representing a substantial difference from what is generally understood in the art.

[0082] As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that, as used herein, the term "and / or" refers to and encompasses any and all possible combinations of one or more of the associated items. It should be further understood that the terms "comprising" and / or "including" used herein specifically refer to the presence of the features, integers, steps, operations, elements, components and / or units, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, units and / or groups thereof.

[0083] The present application discloses several numerical ranges in the text and figures. The disclosed numerical ranges inherently support any range or value (including endpoints) within the disclosed numerical ranges, even if the precise range limitations are not verbatim stated in the specification, because the present disclosure can be practiced within the disclosed numerical ranges.

[0084] For purposes of explanation, the above description has been described with reference to specific embodiments. However, the above illustrative discussion is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations may be made in light of the above teachings. The embodiments are selected and described so as to best explain the principles of the technology and its practical application. Thus, others skilled in the art will be able to best utilize the technology and the various embodiments and various modifications suitable for the particular use contemplated.

[0085] Although the present disclosure and examples have been fully described with reference to the accompanying drawings, it should be noted that various changes and modifications will be apparent to those skilled in the art. Such changes and modifications should be understood to be included within the scope and examples of the present disclosure defined by the claims.

Claims

1. A laser interferometry system, include: a laser emitter configured to emit a laser beam; wherein the laser emitter is a rotated laser diode having a rotated laser beam profile; a beam splitter configured to split the emission laser beam into a first beam split and a second beam split directed toward a single deflector, wherein the first beam split includes a first beam diameter and a second beam diameter, the first beam diameter being larger than the second beam diameter, and the second beam split includes a third beam diameter and a fourth beam diameter, the third beam diameter being larger than the fourth beam diameter; and the single deflector being configured to deflect the first partial beam to intersect the second partial beam, The first light beam diameter is parallel to the third light beam diameter. 2 . The system of claim 1 , wherein the first beam diameter is equal to the third beam diameter and the second beam diameter is equal to the fourth beam diameter.

3. The system of any one of claims 1-2, wherein the first beamlet intersects the second beamlet at an angle of less than 60 degrees.

4. The system of any one of claims 1-2, wherein the transmit laser beam comprises a fifth beam diameter and a sixth beam diameter, the fifth beam diameter being greater than the sixth beam diameter, and at least one of the fifth beam diameter or the sixth beam diameter is increased by passing the transmit laser beam through a cylindrical lens.

5. The system of any one of claims 1-2, wherein the first beam diameter is at least three times the second beam diameter, and the third beam diameter is at least three times the fourth beam diameter.

6. The system of any one of claims 1-2, comprising a processor, a memory, and instructions stored on the memory, the instructions configured to cause the system to calculate a speed at which an object moves through an intersection area.

7. The system of claim 6, wherein the calculation speed is in a direction orthogonal to the first beam diameter and the third beam diameter.

8. The system of claim 6, wherein the object comprises a rope, a wire, a rod, or a flat piece of paper or plastic.

9. The system of claim 1, wherein the beam splitter is a single beam splitter.

10. The system of claim 1, further comprising a single cylindrical lens.

11. The system of claim 1 , wherein the beam splitter is a single beam splitter and further comprises a single cylindrical lens.

12. The system of claim 1, wherein the laser beam profile is expanded from 1.5 to 10 times its initial length.

13. The system of claim 1, wherein the laser beam profile is expanded in a single dimension.

14. The system of claim 1, wherein the laser beam profile is expanded in more than one dimension.

15. A laser interferometry system, include: a laser emitter configured to emit a laser beam; wherein the laser emitter is a rotated laser diode having a rotated laser beam profile; a beam splitter configured to split the emission laser beam into a first beam split and a second beam split directed toward a single deflector, wherein the first beam split includes a first beam diameter and a second beam diameter, the first beam diameter being larger than the second beam diameter, and the second beam split includes a third beam diameter and a fourth beam diameter, the third beam diameter being larger than the fourth beam diameter; and the single deflector being configured to deflect the first partial beam to intersect the second partial beam, wherein the transmit laser beam comprises a fifth beam diameter and a sixth beam diameter, the fifth beam diameter being greater than the sixth beam diameter, and at least one of the fifth beam diameter or the sixth beam diameter is increased by passing the transmit laser beam through a cylindrical lens.

16. The system of claim 15, wherein the first beam diameter is parallel to the third beam diameter.

17. The system of any of claims 15-16, wherein the first beam diameter is equal to the third beam diameter and the second beam diameter is equal to the fourth beam diameter.

18. The system of any of claims 15-16, wherein the first beamlet intersects the second beamlet at an angle of less than 60 degrees.

19. The system of any of claims 15-16, wherein the first beam diameter is at least three times the second beam diameter, and the third beam diameter is at least three times the fourth beam diameter.

20. The system of any one of claims 15-16, comprising a processor, a memory, and instructions stored on the memory, the instructions configured to cause the system to calculate a speed at which an object moves through an intersection area.

21. The system of claim 20, wherein the calculation speed is in a direction orthogonal to the first beam diameter and the third beam diameter.

22. The system of claim 20, wherein the object comprises a rope, a wire, a rod, or a flat piece of paper or plastic.

23. The system of claim 15, wherein the beam splitter is a single beam splitter.

24. The system of claim 15, wherein at least one of the fifth beam diameter or the sixth beam diameter is increased by passing the transmit laser beam through a single cylindrical lens.

25. The system of claim 15, wherein the beam splitter is a single beam splitter, and wherein at least one of the fifth beam diameter or the sixth beam diameter is increased by passing the transmit laser beam through a single cylindrical lens.

26. The system of claim 15, wherein the laser beam profile is expanded from 1.5 times to 10 times its initial length.

27. The system of claim 15, wherein the laser beam profile is expanded in a single dimension.

28. The system of claim 15, wherein the laser beam profile is expanded in more than one dimension.

29. A laser interferometry system, include: a laser emitter configured to emit a laser beam; wherein the laser emitter is a rotated laser diode having a rotated laser beam profile; a beam splitter configured to split the emission laser beam into a first beam split and a second beam split directed toward a single deflector, wherein the first beam split includes a first beam diameter and a second beam diameter, the first beam diameter being larger than the second beam diameter, and the second beam split includes a third beam diameter and a fourth beam diameter, the third beam diameter being larger than the fourth beam diameter; and the single deflector being configured to deflect the first partial beam to intersect the second partial beam, The first beam and the second beam intersect at an angle less than 60 degrees.

30. The system of claim 29, wherein the first beam diameter is equal to the third beam diameter and the second beam diameter is equal to the fourth beam diameter.

31. The system of any of claims 29-30, wherein the first beam segment intersects the second beam segment at an angle of less than 20 degrees.

32. The system of any one of claims 29-30, wherein the first beam diameter is parallel to the third beam diameter.

33. The system of any one of claims 29-30, wherein the transmit laser beam comprises a fifth beam diameter and a sixth beam diameter, the fifth beam diameter being greater than the sixth beam diameter, and at least one of the fifth beam diameter or the sixth beam diameter is increased by passing the transmit laser beam through a cylindrical lens.

34. The system of any one of claims 29-30, wherein the first beam diameter is at least three times the second beam diameter, and the third beam diameter is at least three times the fourth beam diameter.

35. The system of any one of claims 29-30, comprising a processor, a memory, and instructions stored on the memory, the instructions configured to cause the system to calculate a speed at which an object moves through an intersection area.

36. The system of claim 35, wherein the calculation speed is in a direction orthogonal to the first beam diameter and the third beam diameter.

37. The system of claim 35, wherein the object comprises a rope, a wire, a rod, or a flat piece of paper or plastic.

38. The system of claim 29, wherein the beam splitter is a single beam splitter.

39. The system of claim 29, further comprising a single cylindrical lens.

40. The system of claim 29, wherein the beam splitter is a single beam splitter and further comprises a single cylindrical lens.

41. The system of claim 29, wherein the laser beam profile is expanded from 1.5 to 10 times its initial length.

42. The system of claim 29, wherein the laser beam profile is expanded in a single dimension.

43. The system of claim 29, wherein the laser beam profile is expanded in more than one dimension.

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