CN111352181A

CN111352181A - Binary optical element, manufacturing method thereof and projection module

Info

Publication number: CN111352181A
Application number: CN201811569997.7A
Authority: CN
Inventors: 罗孟杰; 郭美杉; 张进
Original assignee: Yuyao Sunny Optical Intelligence Technology Co Ltd
Current assignee: Yuyao Sunny Optical Intelligence Technology Co Ltd
Priority date: 2018-12-21
Filing date: 2018-12-21
Publication date: 2020-06-30

Abstract

A binary optical element, a method for manufacturing the same and a projection module are provided. The binary optical element is used for being combined with a light source and comprises a substrate, a first microstructure and a second microstructure. The first microstructures are arranged on the substrate and used for modulating an input light field of the light source to obtain a plurality of first output light fields. The second microstructure is disposed on the substrate for modulating the input light field of the light source to obtain a plurality of second output light fields, wherein when the first and second microstructures of the binary optical element simultaneously correspond to the input light field of the light source, the first and second output light fields are superimposed on each other to form an output light field pattern.

Description

Binary optical element, manufacturing method thereof and projection module

Technical Field

The invention relates to the technical field of optical diffraction, in particular to a binary optical element, a manufacturing method thereof and a projection module.

Background

Binary optics is an important branch of a physical optics diffraction theory, and is based on the diffraction theory of light waves, and a preset output light field is realized through algorithm iteration. Of course, it can also implement the copy function of the pattern in this way. Binary Optical Element (BOE) is a phase type Diffractive Optical Element (DOE), and is a component for generating a predetermined output light field. The microstructure design of the binary optical element needs to know various parameter performance indexes of an input light field and an output light field, and the output light field is gradually converged to a target light field through an GS algorithm, a genetic algorithm, a simulated annealing method and other iteration modes, which is similar to the phase recovery problem in an optical transformation system.

The conventional binary optical element realizes the copy function of the output light field in a conventional manner, and can realize a regular copy pattern, that is, a single binary optical element can only arrange the copied pattern at a target in order. In this way, only a simple copy pattern can be realized, and a more complicated pattern such as a staggered splicing pattern cannot be realized.

Disclosure of Invention

An object of the present invention is to provide a binary optical element, a method for manufacturing the same, and a projection module, which can realize more complicated patterns such as offset replication, offset splicing, and overlapping splicing by using a single light source.

Another object of the present invention is to provide a binary optical element, a method for manufacturing the same, and a projection module, which can facilitate simplifying the structure of the module configured with the binary optical element and reducing the cost.

Another object of the present invention is to provide a binary optical element, a method for manufacturing the same, and a projection module, which can form a more complicated output optical field distribution while reducing the size of the module, thereby contributing to meeting the demand of the trend of miniaturization.

Another objective of the present invention is to provide a binary optical element, a method for manufacturing the same, and a projection module, wherein in an embodiment of the present invention, a single binary optical element has different microstructures, so that different output light fields modulated by different microstructures are superimposed, which is helpful for obtaining a more complex pattern.

Another objective of the present invention is to provide a binary optical element, a method for manufacturing the same, and a projection module, wherein in an embodiment of the present invention, output light fields modulated by different microstructures of a single binary optical element are distributed in a staggered manner, so as to obtain a staggered output light field pattern.

Another object of the present invention is to provide a binary optical element, a method for manufacturing the same, and a projection module, wherein in an embodiment of the present invention, the projection module can realize a more complicated pattern by using only a single light source and a single binary optical element, which is helpful for reducing the cost.

It is another object of the present invention to provide a binary optical element, a method of manufacturing the same, and a projection module, wherein it is not necessary to use expensive materials or complicated structures in order to achieve the above objects. The invention thus succeeds and effectively provides a solution not only to provide a simple binary optical element and a method for its manufacture and a projection module, but also to increase the practicality and reliability of the binary optical element and the method for its manufacture and the projection module.

To achieve at least one of the above objects or other objects and advantages, the present invention provides a binary optical element for use in combination with a light source, wherein the binary optical element comprises:

a substrate;

a first microstructure, wherein the first microstructure is disposed on the substrate for modulating an input light field of the light source to obtain a plurality of first output light fields; and

a second microstructure disposed on the substrate for modulating the input light field of the light source to obtain a plurality of second output light fields, wherein when the first and second microstructures of the binary optical element simultaneously correspond to the input light field of the light source, the first and second output light fields are superimposed on each other to form an output light field pattern.

In an embodiment of the invention, the first microstructure is different from the second microstructure such that the first output light field modulated by the first microstructure is different from the second output light field modulated by the second microstructure.

In an embodiment of the present invention, the second output light field modulated by the second microstructures is located between the first output light fields modulated by the adjacent first microstructures to form the output light field pattern with a space duplication.

In an embodiment of the invention, the first output light field modulated by the first microstructure and the second output light field modulated by the second microstructure are mutually dislocated to form the dislocated and spliced output light field pattern.

In an embodiment of the invention, the first output light field modulated by the first microstructure and the second output light field modulated by the second microstructure are partially or completely overlapped to form the overlapped and spliced output light field pattern.

In an embodiment of the invention, the binary optical element is further provided with a third microstructure, wherein the third microstructure is disposed on the substrate and is configured to modulate the input light field of the light source to obtain a plurality of third output light fields, wherein the third output light fields are superimposed on the first and second output light fields to form another output light field pattern.

In an embodiment of the invention, the third microstructure is located on the same side of the substrate as the first and second microstructures.

In an embodiment of the invention, the third microstructure is located on a different side of the substrate than the first and second microstructures.

In an embodiment of the invention, the first microstructure is a multi-step phase structure or a continuous phase structure.

In an embodiment of the invention, the second microstructure is a multi-step phase structure or a continuous phase structure.

In an embodiment of the invention, the first and second microstructures are made by an etching process, an imprinting process or a deposition process, respectively.

In an embodiment of the invention, the light source is a vertical cavity surface emitting laser.

According to another aspect of the present invention, there is further provided a projection module, comprising:

a light source for emitting an input light field; and

the binary optical element of any preceding claim, wherein the binary optical element corresponds to an input light field of the light source for modulating the input light field of the light source to project an output light field pattern.

According to another aspect of the present invention, the present invention further provides a method for manufacturing a binary optical element, comprising the steps of:

arranging a first microstructure on a substrate, wherein the first microstructure is used for modulating an input light field of a light source to obtain a plurality of first output light fields; and

and arranging a second microstructure on the substrate, wherein the second microstructure is used for modulating the input light field of the light source to obtain a plurality of second output light fields, and the first output light fields and the second output light fields are mutually superposed to form an output light field pattern.

In an embodiment of the invention, the first microstructure is different from the second microstructure.

In an embodiment of the invention, the first and second microstructures are formed on the substrate by an etching process, an imprinting process or a deposition process, respectively.

In an embodiment of the present invention, the method for manufacturing a binary optical element further includes the steps of:

disposing a third microstructure on the substrate, wherein the third microstructure is configured to modulate the input light field of the light source to obtain a plurality of third output light fields, wherein the third output light fields are superimposed with the first and second output light fields to form the output light field pattern. Further objects and advantages of the invention will be fully apparent from the ensuing description and drawings.

These and other objects, features and advantages of the present invention will become more fully apparent from the following detailed description, the accompanying drawings and the claims.

Drawings

Fig. 1 shows a schematic diagram of a neatly arranged output light field pattern.

Fig. 2 shows a schematic diagram of an output optical field pattern for a mis-splice.

Fig. 3 shows a schematic representation of the application of a binary optical element according to the prior art.

FIG. 4 is a schematic diagram of an application of a binary optical element according to an embodiment of the present invention.

Fig. 5 shows a first variant implementation of the binary optical element according to the above-described embodiment of the invention.

Fig. 6 shows a second variant implementation of the binary optical element according to the above-described embodiment of the invention.

Fig. 7 shows a third variant of the binary optical element according to the above-described embodiment of the invention.

Fig. 8 shows a flow diagram of a method of manufacturing a binary optical element according to an embodiment of the invention.

Detailed Description

The following description is presented to disclose the invention so as to enable any person skilled in the art to practice the invention. The preferred embodiments in the following description are given by way of example only, and other obvious variations will occur to those skilled in the art. The basic principles of the invention, as defined in the following description, may be applied to other embodiments, variations, modifications, equivalents, and other technical solutions without departing from the spirit and scope of the invention.

It will be understood by those skilled in the art that in the present disclosure, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship indicated in the drawings for ease of description and simplicity of description, and do not indicate or imply that the referenced devices or components must be constructed and operated in a particular orientation and thus are not to be considered limiting.

In the present invention, the terms "a" and "an" in the claims and the description should be understood as meaning "one or more", that is, one element may be one in number in one embodiment, and the element may be more than one in number in another embodiment. The terms "a" and "an" should not be construed as limiting the number unless the number of such elements is explicitly recited as one in the present disclosure, but rather the terms "a" and "an" should not be construed as being limited to only one of the number.

In the description of the present invention, it is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In the description of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "connected" and "connected" are to be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be directly connected or indirectly connected through an intermediate. 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 description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Binary optical elements are well known as one type of diffractive optical element that can perform a replication function of the output light field. However, a single conventional binary optical element is provided with only one microstructure, and only regular replication results can be achieved, for example, a neatly arranged output light field pattern (as shown in fig. 1); more complex patterns, such as the output optical field pattern of the mis-splice (as shown in fig. 2), cannot be realized. In other words, a single conventional binary optical element can only realize a simple copying function, and can arrange the copied patterns at the target regularly; more complex patterns such as mis-stitching, mis-replication, etc. cannot be realized.

Currently, in order to realize the output light field pattern shown in fig. 2, the prior art solution generally uses a plurality of light sources corresponding to a plurality of prior binary optical elements. Exemplarily, as shown in fig. 3, two existing binary

optical elements

1P, 2P are arranged side by side and the two existing binary

optical elements

1P, 2P are respectively provided with different microstructures, wherein two

light sources

3P, 4P respectively correspond to the existing binary

optical elements

1P, 2P to modulate an input

light field

301P, 401P from the

light sources

3P, 4P into two

output light fields

302P, 402P by the existing binary

optical elements

1P, 2P. The

output light fields

302P, 402P are displaced from each other to form a complex pattern of displaced mosaics (as shown in fig. 2). Of course, if a more complex output light field pattern is desired, the number of binary optical elements and light sources can be increased accordingly, for example using multiple existing binary optical elements and multiple light sources, to obtain multiple output light fields to form a mis-stitched output light field pattern.

However, the use of two or more binary optical elements in a module such as a projection module or the like inevitably leads to an increase and complexity in the overall structure, which makes the overall size of the module larger, and thus is not in line with the trend of miniaturization. In addition, two or more light sources are used, and corresponding light source control systems have to be configured respectively, so that the number of required components is multiplied, the cost is greatly increased, the whole system is complicated, and the assembly and control difficulty of the module is greatly increased. In particular, in order to obtain output light fields with the same spot structure as shown in fig. 2, it is also necessary to ensure that the input light fields emitted by the two light sources are consistent. This requires the input light fields emitted by the two light sources to be modulated in a consistent manner, and a modulation system has to be additionally added, which further increases the cost, and results in resource waste and low cost performance. Therefore, there is a great need for a new binary optical element to achieve more complex output light field patterns, such as mis-stitching, using only a light source.

Referring to fig. 4 of the drawings, a binary optical element according to an embodiment of the present invention is illustrated, wherein the binary optical element 10 is used in combination with a light source 20 to form a projection module for obtaining a more complex output light field pattern by modulating an input light field 210 of the light source 20. Specifically, the binary optical element 10 includes a substrate 100, a first microstructure 110 and a second microstructure 120, wherein the first microstructure 110 and the second microstructure 120 are disposed on the substrate 100 to form the binary optical element 10 having an integrated structure. The first microstructures 110 are used to modulate the input light field 210 of the light source 20 to obtain a plurality of first output light fields 221. The second microstructures 120 are used to modulate the input light field 210 of the light source 20 to obtain a plurality of second output light fields 222. When the binary optical element 10 is combined with the light source 20, the first microstructures 110 and the second microstructures 120 are configured to collectively correspond to the input light field 210 of the light source 20, and the first output light field 221 and the second output light field 222 are superimposed on each other to form a final output light field pattern 220.

Thus, since only a single binary optical element 10 and a single light source 20 need to be combined to realize a more complicated output light field pattern 220, the binary optical element 10 of the present invention not only can simplify the overall structure and system of the module, which is helpful to greatly save the cost, but also can reduce the overall size of the module, so as to meet the current demand of miniaturization development. In addition, since the module only includes one binary optical element 10 and one light source 20, when the binary optical element 10 and the light source 20 are assembled, only one calibration needs to be performed on the binary optical element 10 and the light source 20, unlike the prior art in which a plurality of binary optical elements and a plurality of light sources need to be calibrated one by one, which not only increases the difficulty of calibration and assembly, but also increases the corresponding cost.

Illustratively, the first microstructure 110 and the second microstructure 120 are disposed on the same side of the substrate 100, and the first microstructure 110 is different from the second microstructure 120, so that a plurality of first output light fields 221 modulated by the first microstructure 110 are different from a plurality of second output light fields 222 modulated by the first microstructure 110, so as to obtain the more complex output light field pattern 220.

In particular, the plurality of first output light fields 221 modulated by the first microstructures 110 and the plurality of second output light fields 222 modulated by the first microstructures 110 are misaligned with each other to form a misaligned replica output light field pattern 220 (as shown in fig. 2). In other words, a plurality of the first output light fields 221 and a plurality of the second output light fields 222 are mis-spliced to form the mis-spliced output light field pattern 220.

It is noted that, as shown in fig. 4, the second output light field 220 modulated by the second microstructures 120 is located between the adjacent first output light fields 210 modulated by the first microstructures 110, that is, the first output light fields 210 are distributed at intervals with the second output light field 220 to form an output light field pattern with a replicated interval.

It is worth mentioning that fig. 5 shows a first variant implementation of the binary optical element 10 according to the above embodiment of the present invention, wherein the second output light field 220 modulated by the second microstructure 120 and the first output light field 210 modulated by the first microstructure 110 may also partially overlap to obtain a more complex overlapped and spliced output light field pattern.

Of course, in another example of the present invention, the second output light field 220 modulated by the second microstructures 120 and the first output light field 210 modulated by the first microstructures 110 may also be all overlapped to obtain a complex overlapped and superimposed output light field pattern.

It is understood that the microstructures on the binary optical element are designed by iterative methods such as GS algorithm, genetic algorithm, simulated annealing, etc. according to the performance indexes of parameters of known input light field and output light field. That is, the first microstructure 110 of the binary optical element 10 is designed according to the input light field 210 and the first output light field 210 of the light source 20; accordingly, the second microstructure 120 of the binary optical element 10 is designed in accordance with the input light field 210 and the second output light field 220 of the light source 20. Thus, various microstructures on the binary optical element can be designed according to the used light source and the preset output light field pattern, so that various complicated output light field patterns are realized, and the practical requirements are met under the condition of ensuring miniaturization and low cost.

It is noted that, in the above embodiments of the present invention, the first and

second microstructures

110 and 120 of the binary optical element 10 may be, but are not limited to, implemented as a multi-step phase structure (including a two-step phase structure, a four-step phase structure, etc.). Of course, in other examples of the present invention, the first and

second microstructures

110, 120 may also be implemented as continuous phase structures; alternatively, the first microstructure 110 is implemented as a multi-step phase structure and the second microstructure 120 is implemented as a continuous phase structure. It is understood that the first and

second microstructures

110, 120 of the binary optical element 10 can also be implemented as other types of phase structures as long as the desired output optical field pattern can be achieved, and the invention is not further limited thereto.

Furthermore, in the above-described embodiments of the present invention, the first and

second microstructures

110 and 120 of the binary optical element 10 may be, but are not limited to being, implemented by etching processes such as electron beam etching, ion beam etching, laser etching, or the like, for example, various relief structures (i.e., phase structures) are etched on the surface of the substrate 100. Of course, in other examples of the present invention, the first and

second microstructures

110 and 120 may also be formed by deposition processes such as thin film deposition, etc., respectively; alternatively, the first microstructure 110 is made by the etching process and the second microstructure 120 is made by the deposition process. It is understood that the first and

second microstructures

110 and 120 of the binary optical element 10 can also be formed by other types of manufacturing processes, such as an imprint process, as long as the desired phase structure can be formed, and the invention is not further limited thereto.

In this embodiment of the present invention, the light source 20 may be, but is not limited to, implemented as a Vertical Cavity Surface Emitting Laser (VCSEL), which is beneficial to further reduce the overall size of the corresponding module by the VCSEL light source with smaller volume. Of course, in other examples of the present invention, the light source 20 may also be implemented as other light sources such as an LED or an LD, etc.

It is worth mentioning that although the features and advantages of the binary optical element 10 of the present invention are illustrated in the descriptions of fig. 4 and 5 and the above embodiments by taking the example that each binary optical element 10 includes only two microstructures as an example, it can be understood by those skilled in the art that the binary optical element 10 disclosed in fig. 4 and 5 and the above description is only an example and does not limit the content and scope of the present invention, for example, in other examples of the binary optical element 10, the number of microstructures may be more than two so as to obtain a more complex output optical field pattern.

Fig. 6 shows a second variant embodiment of the binary optical element 10 according to the embodiment of the invention, wherein a third microstructure 130 is provided on the substrate 100 of the binary optical element 10, wherein the third microstructure 130 is located on the same side of the substrate 100 as the first and second microstructures 120, and the second microstructure 120 is located between the first microstructure 110 and the third microstructure 130, wherein the third microstructure 130 is used to modulate the input light field 210 of the light source 20 to obtain a plurality of third output light fields 223, wherein the third microstructure 130 of the binary optical element 10 also corresponds to the input light field 210 of the light source 20, and the third output light fields 223 are superimposed with the first and second output light fields 221, 222 to form the output light field pattern 220. Thus, in this first variant embodiment of the present invention, the output light field pattern 220 formed by the superposition of the first output light field 221, the second output light field 222 and the third output light field 223 is more complex than the output light field pattern formed by the superposition of the first and second output light fields 221, 222 according to the above-mentioned embodiment of the present invention, so as to meet the needs of various specific situations.

In particular, although in this second variant embodiment of the invention the number of microstructures on a single binary optical element 10 is increased, the overall dimensions of the binary optical element 10 can remain unchanged compared to the above-described examples of the invention, i.e. the dimensions of the first and

second microstructures

110, 120 are reduced accordingly, in order to make room for the third microstructure 130. This allows the size of the binary optical element 10 to be kept constant while further increasing the complexity of the output light field pattern 220 to meet the demands of the trend of miniaturization.

It is noted that in other examples of the present invention, the first and

second microstructures

110 and 120 of the binary optical element 10 can be located on the same side of the third microstructure 130, so that three output light fields are superimposed at another angle to obtain another output light field pattern, of course, in still another example of the present invention, the binary optical element 10 can be provided with a plurality of microstructures (such as an array distribution of 2 × 2, an array distribution of 2 × 3, etc.) distributed in an array to obtain different output light field patterns.

It should be noted that a plurality of microstructures of the binary optical element 10 may also be respectively located on different sides of the substrate 100, so that output optical fields modulated by different microstructures are mutually superimposed to obtain a more complex output optical field pattern.

Fig. 7 shows a third variant embodiment of the binary optical element 10 according to the embodiment of the invention, wherein a third microstructure 130 is provided on the substrate 100 of the binary optical element 10, wherein the third microstructure 130 is located on a different side of the substrate 100 than the first and second microstructures 120, i.e. the first and

second microstructures

110, 120 are located on the bottom side of the substrate 100 and the third microstructure 130 is located on the top side of the substrate 100, wherein the third microstructure 130 is used for modulating the input light field 210 of the light source 20 to obtain a plurality of third output light fields 223, wherein the third microstructure 130 of the binary optical element 10 also corresponds to the input light field 210 of the light source 20 and the third output light fields 223 are superimposed with the first and second output light fields 221, 222, to form the output light field pattern 220. In this way, in this second variant embodiment of the invention, the output light field pattern 220 is formed by the superposition of the first output light field 221, the second output light field 222 and the third output light field 223, in order to meet the needs of each specific case.

According to another aspect of the present invention, the present invention further provides a method of manufacturing a binary optical element. Specifically, as shown in fig. 8, the method for manufacturing the binary optical element 10 includes the steps of:

s310: disposing a first microstructure 110 on a substrate 100, wherein the first microstructure 110 is configured to modulate an input light field 210 of a light source 20 to obtain a plurality of first output light fields 221; and

s320: disposing a second microstructure 120 on the substrate 100, wherein the second microstructure 120 is configured to modulate the input light field 210 of the light source 20 to obtain a plurality of second output light fields 222, wherein the first and second output light fields 221, 222 are superimposed to form an output light field pattern 220.

In an example of the invention, in the step S310, the first microstructure 110 may be etched on the substrate 100 through an etching process. Of course, in another example of the present invention, in the step S310, the first microstructure 110 may also be deposited on the substrate 100 by a deposition process. In another example of the present invention, the step S310 may further stamp the first microstructure 110 on the substrate 100 through a stamping process.

In an example of the present invention, in the step S320, the second microstructure 120 is etched on the substrate 100 through an etching process. Of course, in another example of the present invention, in the step S320, the second microstructure 120 may also be deposited on the substrate 100 by a deposition process. In addition, in another example of the present invention, the step S320 may further stamp the second microstructure 110 on the substrate 100 through a stamping process.

It is noted that in one example of the present invention, the first microstructure 110 is different from the second microstructure 120, such that the first output light field 221 modulated by the first microstructure 110 is different from the second output light field 222 modulated by the second microstructure 120.

Further, in an example of the present invention, the first output light field 221 modulated by the first microstructure 11 and the second output light field 222 modulated by the second microstructure 12 are distributed in a staggered manner to form the output light field pattern 220 of a staggered joint.

In this embodiment of the present invention, as shown in fig. 8, the method for manufacturing the binary optical element 10 may further include the steps of:

s330: disposing a third microstructure 130 on the substrate 100, wherein the third microstructure 130 is configured to modulate the input light field 210 of the light source 20 to obtain a plurality of third output light fields 223, wherein the third output light fields 223 are superimposed with the first and second output light fields 221, 222 to form the output light field pattern 220.

Further, in some examples of the present invention, the third microstructure 130 may be disposed on the substrate 100 through an etching process, an imprinting process, or a deposition process.

It should be noted that, in the manufacturing method of the binary optical element 10, the steps S310, S320, and S330 are not in sequence, that is, the steps S310, S320, and S330 may be executed simultaneously or separately, for example, the step S320 is executed first, and then the step S310 and the step S330 are executed, and the invention is not limited thereto.

It will be appreciated by persons skilled in the art that the embodiments of the invention described above and shown in the drawings are given by way of example only and are not limiting of the invention. The objects of the invention have been fully and effectively accomplished. The functional and structural principles of the present invention have been shown and described in the examples, and any variations or modifications of the embodiments of the present invention may be made without departing from the principles.

Claims

1. A binary optical element for use in conjunction with a light source, wherein the binary optical element comprises:

a substrate;

2. The binary optical element of claim 1, wherein said first microstructure is different from said second microstructure such that said first output light field modulated by said first microstructure is different from said second output light field modulated by said second microstructure.

3. The binary optical element of claim 2, wherein said second output light field modulated by said second microstructures is located between said first output light fields modulated by adjacent said first microstructures to form said output light field pattern that is a spaced replica.

4. The binary optical element of claim 1, wherein said first output light field modulated by said first microstructure and said second output light field modulated by said second microstructure are misaligned with each other to form said misaligned-spliced output light field pattern.

5. The binary optical element of claim 1, wherein the first output light field modulated by the first microstructures partially or fully overlaps the second output light field modulated by the second microstructures to form the overlapped-spliced output light field pattern.

6. The binary optical element of any one of claims 1 to 5, further provided with a third microstructure, wherein said third microstructure is provided on said substrate for modulating the input light field of the light source to obtain a plurality of third output light fields, wherein said third output light fields are superimposed on said first and second output light fields to form another output light field pattern.

7. The binary optical element of claim 6, wherein the third microstructure is on the same side of the substrate as the first and second microstructures.

8. The binary optical element of claim 6, wherein the third microstructure is on a different side of the substrate than the first and second microstructures.

9. The binary optical element according to any one of claims 1 to 5, wherein the first microstructure is a multi-step phase structure or a continuous phase structure.

10. The binary optical element of claim 9, wherein said second microstructure is a multi-step phase structure or a continuous phase structure.

11. The binary optical element according to any one of claims 1 to 5, wherein said first and second microstructures are made by an etching process, an embossing process or a deposition process, respectively.

12. The binary optical element of any one of claims 1 to 5, wherein said light source is a vertical cavity surface emitting laser.

13. A projection module, comprising:

a light source for emitting an input light field; and

the binary optical element of any one of claims 1 to 12, wherein said binary optical element corresponds to an input light field of said light source for modulating the input light field of said light source to project an output light field pattern.

14. A method of manufacturing a binary optical element, comprising the steps of:

15. The method of manufacturing a binary optical element according to claim 14, wherein said first microstructure is different from said second microstructure.

16. The method of manufacturing a binary optical element according to claim 15, wherein said first and second microstructures are formed on said substrate by an etching process, an imprinting process, or a deposition process, respectively.

17. The method for manufacturing a binary optical element according to any one of claims 14 to 15, further comprising the steps of:

disposing a third microstructure on the substrate, wherein the third microstructure is configured to modulate the input light field of the light source to obtain a plurality of third output light fields, wherein the third output light fields are superimposed with the first and second output light fields to form the output light field pattern.