A method for aligning and assembling a double-layered diffractive optical element

Abstract

This invention provides a method for aligning and assembling a double-layer diffractive optical element, comprising the following steps: S1, aligning and installing the double-layer diffractive optical element; S2, treating the double-layer diffractive optical element as a single refractive element and participating in the assembly of other optical elements. This invention applies alignment marks to the two-layer diffractive optical element, effectively simplifying the assembly process, and is simple, reasonable, highly accurate, and low-cost.

Description

Technical Field

[0001] This invention belongs to the field of optical technology, specifically relating to a method for alignment marking and assembly of a double-layer diffractive optical element. Background Technology

[0002] Existing assembly techniques for diffractive optical elements still follow the assembly methods used for refractive optical elements. Generally, optical focusing devices are employed to measure the offset of parallel light rays for positioning, or to measure the offset of the reflected image at the optical null position. During this process, an XY detector is used to measure the position of the focal point to adjust the position of each component. However, this method presents significant difficulties when assembling and adjusting optical systems containing double-layer diffractive optical elements. These difficulties are: 1. Double-layer diffractive optical elements consist of two layers of harmonic diffractive optical elements. Each layer does not have a fixed single focal point but rather multiple focal points, which complicates positioning. 2. The image formed by the first layer of harmonic diffractive optical elements has a large spot of confusion on the focal plane, making it difficult to determine the center position. Only after passing through two layers of diffractive elements can a smaller spot of confusion be formed. This further complicates the assembly and adjustment of double-layer diffractive optical elements. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for alignment marking and assembly of double-layer diffractive optical elements, which is simple and reasonable to operate, highly accurate, and can effectively simplify the assembly process of double-layer diffractive optical elements.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for alignment marking and assembly of a double-layer diffractive optical element, characterized by comprising the following steps:

[0005] S1. Apply concentric arc lines as alignment marks near the edge of each layer of optical elements, and install and adjust the double-layer diffractive optical elements.

[0006] S2. The installed and debugged double-layer diffractive optical element is used as a whole as a refractive element in the installation of other optical elements.

[0007] Preferably, the specific operation of S1 is as follows:

[0008] S101. Fix the first layer of diffractive optical elements so that the alignment mark faces upward, and set a ring of optical photosensitive adhesive on the edge of the top surface of the first layer of diffractive optical elements.

[0009] S102. Place the second layer of diffractive optical elements directly above the first layer of diffractive optical elements, and perform rough alignment using the outer edges of the two layers of diffractive optical elements.

[0010] S103. Use alignment marks to precisely align the two layers of diffractive optical elements to ensure that the alignment marks of the two layers of optical elements completely correspond and cover each other.

[0011] S104. Use ultraviolet light to irradiate the optical photosensitive adhesive to complete the assembly and debugging of the double-layer diffractive optical element.

[0012] Preferably, the alignment mark includes three sets of concentric arcs, the concentric arcs in the same set are of different lengths at the same center, the length of the concentric arcs in the same set decreases from the inside to the outside, and the three sets of concentric arcs are arranged in a ring array with a 120° interval.

[0013] Preferably, the alignment mark is located at the horizontal boundary of the outer periphery of the relief surface of the diffractive optical element.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. This invention simplifies the assembly and adjustment process of double-layer diffractive optical elements by applying alignment marks, and when combined with existing diffractive optical element processing methods, it does not incur additional processing costs. It also offers good coaxiality of the annular bands with existing diffractive optical elements and high horizontal control precision.

[0016] 2. In this invention, the double-layer diffractive optical element is installed first and regarded as a whole, and is approximated as a refractive element for subsequent assembly and adjustment. The double-layer diffractive optical element has a definite and unique principal focus, and the dispersion spot on the focal plane is not large, making it very easy to align. It can be used as an ordinary refractive optical element to participate in the assembly and adjustment of the optical system, which can overcome the problem of the difficulty in determining the focus of a single-layer diffractive optical element and simplify the assembly and adjustment process of the optical system.

[0017] 3. Since the current ring period width of double-layer diffractive optical elements is in the micrometer range, they are mostly manufactured using single-point diamond turning technology. The alignment mark combined with the turning process of this invention applies coaxial circular arc lines to the periphery of each layer of diffractive optical element. The concentric circular arc lines are easy to process during the turning process, have high precision, and remain parallel to the surface shape of the diffractive optical element.

[0018] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the present invention, which sets alignment marks on two layers of diffractive optical elements. Detailed Implementation

[0020] This invention includes the following steps:

[0021] S1. Apply concentric arc lines as alignment marks near the edge of each layer of optical elements, and install and adjust the double-layer diffractive optical elements.

[0022] S2. The installed and debugged double-layer diffractive optical element is used as a whole as a refractive element in the installation of other optical elements.

[0023] In this embodiment, the specific operation of S1 is as follows:

[0024] S101. Fix the first layer of diffractive optical elements with the alignment mark facing upwards, and apply a ring of optical photosensitive adhesive around the edge of the optical elements;

[0025] S102. Place the second layer of diffractive optical elements directly above the first layer of diffractive optical elements, and perform rough alignment using the outer edges of the two layers of diffractive optical elements. The edges of the second layer of diffractive optical elements are also coated with photosensitive adhesive.

[0026] S103. Use alignment marks to perform precise alignment of the two layers of diffractive optical elements to ensure that the alignment marks of the two layers of optical elements correspond and cover each other.

[0027] S104. Use ultraviolet light to irradiate the optical photosensitive adhesive to complete the assembly and debugging of the double-layer diffractive optical element.

[0028] In this embodiment, the alignment mark includes three sets of concentric arcs. The concentric arcs in the same set have different lengths at the same center. The lengths of the concentric arcs in the same set decrease sequentially from the inside to the outside. The three sets of concentric arcs are arranged in a ring array with a 120° interval.

[0029] In this embodiment, the alignment mark is located at the horizontal boundary of the outer periphery of the relief surface of the diffractive optical element.

[0030] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for alignment marking and assembly of a double-layer diffractive optical element, characterized in that, Includes the following steps: S1. Apply concentric arc lines near the edge of each optical element as alignment marks, and install and adjust the double-layer diffractive optical element. The specific operation is as follows: S101. Fix the first layer of diffractive optical elements so that the alignment marks face upwards, and set a ring of optical photosensitive adhesive around the edge of the optical elements; S102. Place the second layer of diffractive optical elements directly above the first layer of diffractive optical elements, and perform rough alignment using the outer edges of the two layers of diffractive optical elements. S103. Use alignment marks to precisely align the two layers of diffractive optical elements to ensure that the alignment marks of the two layers of optical elements completely correspond and cover each other. S104. Use ultraviolet light to irradiate the optical photosensitive adhesive to complete the assembly and debugging of the double-layer diffraction optical element; S2. The installed and debugged double-layer diffractive optical element is used as a whole as a refractive element in the installation of other optical elements; The alignment marks include three sets of concentric arcs. The concentric arcs in the same set are of different lengths from the center. The lengths of the concentric arcs in the same set decrease from the inside to the outside. The three sets of concentric arcs are arranged in a ring array with a 120° interval.

2. The alignment marking and assembly method for a double-layer diffractive optical element according to claim 1, characterized in that, Alignment marks are placed at the horizontal boundary of the outer perimeter of the relief surface of the diffractive optical element.

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