阅读说明：本技术 衍射光学元件、包括其的光学组件以及基准线投射装置 (Diffractive optical element, optical module including the same, and reference line projection apparatus ) 是由 王燚言 尹晓东 于 2019-11-15 设计创作，主要内容包括：本发明涉及一种用于投射出基准线的衍射光学元件,所述衍射光学元件包括成二维阵列状周期排布的多个微结构图案单元,每个所述微结构图案单元的相位分布被配置成,接收激光并调制所述激光投射出所述基准线,其中所述衍射光学元件在至少一个方向上的视场角大于等于90度。本发明还涉及一种包括该衍射光学元件的光学组件。本发明提出了一种衍射光学元件(DOE),代替传统的折射光学元件,形成所需要的激光基准线。因为DOE具有极高的设计自由度,目标光场不局限于一字线、十字线,还可以设计更多复杂的激光基准线,例如网格线。对于激光标准线为十字线的情况,只需要设计一片DOE即可实现,不需要像两个折射光学元件那样进行垂直方向的对准安装。(The invention relates to a diffractive optical element for projecting a reference line, which comprises a plurality of microstructure pattern units which are periodically arranged in a two-dimensional array, the phase distribution of each microstructure pattern unit is configured to receive laser light and modulate the laser light to project the reference line, wherein the angle of field of the diffractive optical element in at least one direction is greater than or equal to 90 degrees. The invention also relates to an optical assembly comprising the diffractive optical element. The invention provides a Diffractive Optical Element (DOE) which replaces a traditional refractive optical element to form a required laser reference line. Because the DOE has extremely high design freedom, the target light field is not limited to a word line and a cross line, and more complicated laser reference lines, such as grid lines, can be designed. For the case that the laser standard line is a cross line, the laser standard line can be realized by only designing one DOE, and the alignment and installation in the vertical direction are not needed like two refractive optical elements.)

1. A diffractive optical element for projecting a reference line,

the diffractive optical element comprises a plurality of microstructure pattern units which are periodically arranged in a two-dimensional array, the phase distribution of each microstructure pattern unit is configured to receive laser and modulate the laser to project the reference line,

wherein a field angle of the diffractive optical element in at least one direction is 90 degrees or more.

2. The diffractive optical element according to claim 1, wherein the reference lines include a horizontal reference line and a vertical reference line, and the angles of view of the diffractive optical element in both the horizontal direction and the vertical direction are 90 degrees or more.

3. The diffractive optical element according to claim 2, wherein angles of view of the diffractive optical element in both the horizontal direction and the vertical direction are 110 degrees or more.

4. The diffractive optical element according to one of claims 1 to 3, characterized in that the period of the microstructure pattern units has a size smaller than the size of the incident light field of the laser light on the diffractive optical element.

5. The diffractive optical element according to claim 4, characterized in that the incident light field can cover at least two microstructure pattern units.

6. The diffractive optical element according to claim 4, wherein the diffractive optical element is configured such that: the incident light field irradiated on the plurality of microstructure pattern units forms a datum line in a dotted line after diffraction modulation of the microstructure pattern units and interference modulation between the plurality of microstructure pattern units.

7. Diffractive optical element according to claim 6, characterized in that the period of the microstructure pattern elements is 100um x 100um to 2mm x 2mm and the size of the incident optical field is 500um x 500um to 5mm x 5mm, wherein preferably the period of the microstructure pattern elements is 500um x 500um to 1mm x 1mm and the size of the incident optical field is 1mm x 1mm to 3 mm.

8. An optical assembly for projecting a reference line, the optical assembly comprising:

a laser light source configured to emit laser light; and

the diffractive optical element according to any one of claims 1 to 7.

9. The optical assembly of claim 8 wherein the laser light source is a divergent light source and the diffractive optical element is designed for collimated light, the optical assembly further comprising a collimating lens between the laser light source and the diffractive optical element to shape the laser light emitted by the laser light source into collimated light.

10. The optical assembly of claim 8, wherein the laser light source is a divergent light source and the diffractive optical element is designed for the divergent light source.

11. A reference line projection arrangement, characterized in that the reference line projection arrangement comprises an optical assembly according to any one of claims 8-10.

Technical Field

The present invention generally relates to the field of optical technology, and more particularly, to a diffractive optical element for projecting a reference line, an optical assembly including the diffractive optical element, and a reference line projection apparatus.

Background

The laser demarcation device is widely applied to the building construction industry and is used for projecting a laser reference line so as to improve the construction precision. The laser projector commonly available on the market has a word line and a cross line, and the realization method is usually to collimate the divergent light emitted from the laser diode and then to form the required light field (reference line) by a Refractive Optical Element (ROE) such as a cylindrical lens. The existing laser demarcation device for realizing the cross line by utilizing the refraction optical element has the problems of vertical alignment of two vertical cylindrical lenses, higher installation difficulty and poorer shock resistance.

Disclosure of Invention

In view of at least one of the drawbacks of the prior art, the present invention provides a diffractive optical element, an optical assembly including the diffractive optical element, and a reference line projection apparatus.

According to an aspect of the present invention, there is provided a diffractive optical element for projecting a reference line, the diffractive optical element comprising a plurality of microstructure pattern units periodically arranged in a two-dimensional array, each microstructure pattern unit having a phase distribution configured to receive laser light and modulate the laser light to project the reference line, wherein an angle of view of the diffractive optical element in at least one direction is 90 degrees or greater.

According to another aspect of the present invention, the reference line includes a horizontal reference line and a vertical reference line, and the angle of view of the diffractive optical element in both the horizontal direction and the vertical direction is 90 degrees or more.

According to another aspect of the present invention, the angles of view of the diffractive optical element in both the horizontal direction and the vertical direction are 110 degrees or more.

According to another aspect of the present invention, the size of the period of the microstructure pattern unit is smaller than the size of the incident light field of the laser light on the diffractive optical element.

According to another aspect of the invention, the incident light field may cover at least two of the microstructure pattern units.

According to another aspect of the invention, the diffractive optical element is configured such that: the incident light field irradiated on the plurality of microstructure pattern units forms a datum line in a dotted line after diffraction modulation of the microstructure pattern units and interference modulation between the plurality of microstructure pattern units.

According to another aspect of the invention, the period of the microstructure pattern unit is 100um x 100um to 2mm x 2mm and the size of the incident optical field is 500um x 500um to 5mm x 5mm, wherein preferably the period of the microstructure pattern unit is 500um x 500um to 1mm x 1mm and the size of the incident optical field is 1mm x 1mm to 3mm x 3 mm.

The present invention also provides an optical assembly for projecting a reference line, comprising:

a laser light source configured to emit laser light; and

the diffractive optical element described above.

According to another aspect of the invention, the laser light source is a divergent light source, the diffractive optical element is designed for collimating light, and the optical assembly further comprises a collimating lens between the laser light source and the diffractive optical element, so as to shape the laser light emitted by the laser light source into collimated light.

According to another aspect of the invention, the laser light source is a divergent light source and the diffractive optical element is designed for the divergent light source.

The invention also provides a datum line projection device which comprises the optical assembly.

The invention designs a Diffraction Optical Element (DOE) which replaces a traditional ROE element to form a required laser reference line. Because the DOE has extremely high design freedom, the target light field is not limited to a word line and a cross line, and more complicated laser reference lines, such as grid lines, can be designed. For the case that the laser standard line is a cross line, the laser standard line can be realized by only designing one DOE, and the alignment and installation in the vertical direction are not needed like two refractive optical elements.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 shows a schematic view of an optical assembly for projecting a reference line according to one embodiment of the present invention;

FIG. 2 is a schematic view showing a diffractive optical element according to the present invention and a partial phase distribution of one of the microstructure pattern units;

two embodiments of reference lines are shown in FIGS. 3A and 3B, respectively;

FIG. 4 shows a reference line projected by a single microstructure pattern unit and a partial magnified view thereof;

FIG. 5 illustrates a projected reference line and a partial enlarged view thereof according to one embodiment of the present invention; and

FIG. 6 shows a schematic view of an optical assembly for projecting a reference line according to another embodiment of the present invention.

Detailed Description

In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the description of the present invention, it should be noted that unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection, either mechanically, electrically, or in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly above and obliquely above the second feature, or simply meaning that the first feature is at a lesser level than the second feature.

The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or uses of other materials.

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.

FIG. 1 shows a schematic view of an optical assembly 10 for projecting a reference line according to one embodiment of the present invention, described in detail below with reference to FIG. 1.

As shown in fig. 1, the optical assembly 10 includes a laser light source 11, a collimator lens 12, and a diffractive optical element 13. The laser light source 11 is, for example, a laser diode LD, and emits a laser beam when driven. The laser beam from the laser light source 11 is incident on the collimator lens 12, is shaped and modulated into a parallel beam by the collimator lens 12, and then is incident on the diffractive optical element 13 downstream of the optical path.

Fig. 2 shows a schematic view of a diffractive optical element according to the present invention and a partial phase distribution of one of the microstructure pattern units. As shown in the left side of fig. 2, the diffractive optical element 13 of the present invention includes a plurality of, for example, G × H microstructure pattern units, which are periodically arranged in a two-dimensional array, wherein each microstructure pattern unit has the same phase distribution pattern. The right side of fig. 2 also shows a partial phase distribution pattern of one microstructure pattern unit of the diffractive optical element, which is an 8-step element as shown in the figure, where different grayscales represent different step heights, i.e., different phases. Each microstructure pattern unit on the diffractive optical element 13 is capable of changing the phase distribution of the wave surface of light incident thereon, thereby modulating the transmission of light such that the output light beam conforms to a preset light intensity distribution and light field pattern. In the present invention, the phase distribution of each microstructure pattern unit is configured to receive laser light and modulate the laser light to project the reference line. Two embodiments of the reference lines are shown in fig. 3A and 3B, respectively, the reference lines in fig. 3A being cross-shaped and including horizontal and vertical reference lines, and the reference lines in fig. 3B being tessellated, the plurality of horizontal and vertical reference lines intersecting one another to form a tessellation. Those skilled in the art will readily appreciate that the scope of the present invention is not limited to a particular reference line type, but may be a word line, including only horizontal or vertical reference lines, for example.

The angle of view of the diffractive optical element 13 according to the present invention in at least one direction is 90 degrees or more. Shown in fig. 1 is a schematic view of the optical assembly 10, and as shown in the drawing, the angle of field θ of the diffractive optical element 13 in the horizontal direction is 90 degrees or more. Additionally or alternatively, the angle of field of the diffractive optical element 13 in the vertical direction is likewise equal to or greater than 90 degrees. In addition, according to one preferred embodiment of the present invention, the angles of view of the diffractive optical element 13 in both the horizontal direction and the vertical direction are 110 degrees or more.

The diffractive optical element of the present invention has a larger projection area, i.e., a larger angle of view, than a typical diffractive optical element. The field angle of a typical diffractive optical element is generally small, for example, less than 60 degrees, and can be designed according to the paraxial approximation principle. However, since the laser projector is required to project a reference line as long as possible within a small projection distance, the angle of view of the diffractive optical element used for the laser projector is required to be as large as possible, for example, 90 degrees or more, and preferably 110 degrees or more. Under the condition that the field angle is large, the target pattern designed by the conventional design method is unevenly distributed on a plane in a bright middle and dark periphery mode, the reference line of the laser projector is taken as an example, the part of the line, which is located near the center of the projection area, is bright, and the brightness of the line becomes dark gradually as the line extends to the edge of the projection area. This is because the brightness distribution of the target pattern designed by the conventional design method is uniform on a spherical surface, but the projection onto a plane is distorted, and the edge pixels are elongated to cause a decrease in brightness. Aiming at the problem, the diffractive optical element of the invention carries out distortion correction in the design process, namely, carries out brightness compensation on the edge area of the reference line, thereby ensuring that the reference line presents a straight line with more uniform brightness in a larger view field range.

In addition, since the field angle of the diffractive optical element to be designed is relatively large, the phase distribution of the diffractive optical element obtained by the conventional design method has many characteristic regions with very small size, for example, a few hundred nanometers of tiny characteristics, and the tiny characteristic phases contain high-frequency component information, which affects the large-angle energy distribution of the target light field. However, due to the limitation of the processing level, these tiny features are difficult to process, which causes the deviation between the actually processed diffraction optical element morphology and the theoretical design morphology, and thus causes the deviation between the actual target light field and the preset target light field. The inventor of the present invention has made a feature size limitation in the design process of the diffractive optical element in consideration of the existing process level, thereby ensuring consistency of the manufacturing result and the design result.

In addition, because laser has high coherence, a target pattern formed by projection of the diffractive optical element has a relatively obvious speckle effect, and for the design of a reference line of the laser line projector, the line has irregular granular dark spots and is not beautiful enough, as shown in fig. 4. In fig. 4, the left side shows the cross lines projected by the single microstructure pattern unit of the diffractive optical element, and the right side is a partially enlarged graph of the cross lines, wherein a large number of irregular granular dark spots can be seen, and the reference line is not clear and beautiful. In view of this problem, according to an embodiment of the present invention, the period size of the microstructure pattern unit of the diffractive optical element may be adjusted, so that the incident light field emitted from the laser light source is irradiated onto a plurality of periods of the diffractive optical element, and diffraction images formed by the plurality of periods on the diffractive optical element interfere with each other, so that so-called continuous lines originally formed by diffraction of a single period interfere with each other to form a dotted line distribution, so that no obvious irregular speckle is observed on the target pattern, and the beauty of the cross line is improved.

According to a preferred embodiment of the present invention, the size of the period of the microstructure pattern unit is smaller than the size of the incident light field of the laser light on the diffractive optical element 13. Preferably, the incident light field may cover at least two of the microstructure pattern units. Since the incident light field irradiates on at least two microstructure pattern units, a reference line in the form of a dotted line is formed after diffraction modulation of the microstructure pattern units and interference modulation between the plurality of microstructure pattern units, as shown in fig. 5.

The period of the diffractive optical element refers to a basic unit of a phase distribution designed according to an incident light field and a target light field, i.e., a target pattern, and the period size can be set according to specific design requirements, and the period length can be, for example, several hundred micrometers to several millimeters, such as 200um to 5 mm. The larger the period is, the smaller the dot pitch of dot lines formed by the interference between the periods is, and conversely, the smaller the period is, the larger the dot pitch of dot lines formed by the interference between the periods is. According to a preferred embodiment of the present invention, the period of the microstructure pattern elements is 100um x 100um to 2mm x 2mm, and the size of the incident optical field is 500um x 500um to 5mm x 5 mm. Preferably, the microstructure pattern elements have a period of 500um x 500um to 1mm x 1mm, and the incident optical field has a size of 1mm x 1mm to 3mm x 3 mm.

The machining accuracy (i.e., the minimum feature size) of the diffractive optical element determines the number of phase distributions in a single period of the diffractive optical element. In the case where the period is constant, the smaller the minimum feature size is, the larger the number of phase distributions is, and the higher the design flexibility of the diffractive optical element is, and a more flexible and complicated target pattern can be designed. But limited by the level of the fabrication process of diffractive optical elements, the minimum feature size is typically a few hundred nanometers to a few micrometers, e.g., 200nm to 5 um. In the preferred embodiment of the present invention, the minimum feature size is 200nm, the period is 700um, and the size of the incident light field of the laser light source is 2 mm.

The laser light source 11 shown in fig. 1 is a divergent light source, and the diffractive optical element 13 is designed for collimated light, so a collimating lens 12 needs to be disposed between the laser light source 11 and the diffractive optical element 13, so as to shape the laser light emitted from the laser light source 11 into collimated light. Those skilled in the art will readily appreciate that the present invention is not so limited. For example, the laser light source 11 may be a divergent light source, the diffractive optical element is designed for the divergent light source, as schematically shown in fig. 6, wherein the optical assembly 10' includes a laser light source and a diffractive optical element, the laser light source is a divergent light source, the diffractive optical element is designed for the divergent light source, for example, a fresnel diffractive lens similar to a collimating lens in function may be designed and a phase distribution pattern is obtained, then a DOE for collimated light is designed and a corresponding phase distribution pattern is obtained, and then the two phase patterns are superimposed. The diverging laser beam can thus be received directly and modulated to project a light field pattern similar to that of figures 4 and 5. In addition, various features of the embodiments described with reference to FIGS. 1-5 may be incorporated into the embodiment of FIG. 6 without the need for inventive labor.

On the other hand, the design scheme aiming at the collimated light has higher safety risk for human eyes, the LD forms parallel laser beams after passing through the collimating lens, the power density is very high, and if the ROE is damaged, the parallel laser beams can directly irradiate the human eyes, so that the human eyes are greatly damaged. And aiming at the design scheme of the divergent light, the collimating link is omitted, and the laser beam is divergently transmitted, so that the power density of the laser beam is lower after a certain distance from the laser light source, and the risk of eye safety is reduced. Under the same requirement of human eye safety, the design scheme of the divergent light can adopt an LD light source with higher power.

The invention also relates to a reference line projection device comprising an optical assembly 10 as described above.

The invention provides a Diffractive Optical Element (DOE) which replaces a traditional ROE element and forms a required laser reference line. Because the DOE has extremely high design freedom, the target light field is not limited to a word line and a cross line, and more complicated laser reference lines, such as grid lines, can be designed. For the case that the laser standard line is a cross line, the laser standard line can be realized by only designing one DOE, and the alignment and installation in the vertical direction are not needed like two refractive optical elements.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein. Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.