CN211928320U - Diffraction light projection device - Google Patents
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- CN211928320U CN211928320U CN201921978307.3U CN201921978307U CN211928320U CN 211928320 U CN211928320 U CN 211928320U CN 201921978307 U CN201921978307 U CN 201921978307U CN 211928320 U CN211928320 U CN 211928320U
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Abstract
The utility model provides a diffraction light projection arrangement, including light emitting source and diffraction optical module. The light source is used for outputting a light beam, and the diffraction optical module is used for allowing the light beam output by the light source to pass through to form diffraction light projected outwards. The diffraction optical module comprises a first diffraction optical element and a second diffraction optical element which are arranged in a stacked mode, wherein the first diffraction optical element and the second diffraction optical element are made of different materials and used for extending the usable wavelength range of the light beam together. The utility model discloses can extend diffraction optical module to the usable wavelength range of incident to light beam wherein, promote the design degree of freedom of diffraction optical module.
Description
Technical Field
The present invention relates to an optical device, and more particularly to a diffraction light (diffraction light) projection device.
Background
With the evolution of electronic industry and the vigorous development of industrial technology, various electronic devices are developed and designed in a direction of being portable and easy to carry, so that users can apply to mobile commerce, entertainment, leisure and the like at any time and any place. In addition, in recent years, as the degree of the integration and application of the machine, the light and the electricity is increasing, various optical devices are being widely extended to various products, such as smart phones and portable electronic devices which are small and convenient to carry, and the like, so that users can take out and use the optical devices at any time when they need them, which not only has important commercial value, but also adds color to the daily life of the general public.
Further, as the quality of life is improved, more diversified functions of electronic devices are desired, and thus, more demands such as stereoscopic (3D) sensing are required for optical devices applied to the electronic devices, and some applications related to diffractive optical elements have been proposed to meet the demands. For example, please refer to fig. 1, which is a conceptual diagram of a stereo sensing implementation using structured light technology. Fig. 1 illustrates that a laser beam L11 output by the laser light source 11 passes through the collimating element 13 and is collimated and incident on the diffractive optical element 12, and the collimated laser beam L11' passes through the diffractive optical element 12 to form a structured light (structured light) L12 projecting outward, so that a corresponding structured light pattern 14 can be presented in space for stereo sensing, wherein the structured light pattern 14 shown in fig. 1 is a dot pattern (dot pattern). For another example, please refer to fig. 2, which is a schematic diagram illustrating a conventional Time of flight (TOF) implementation of stereo sensing. Fig. 2 illustrates that the laser beams L21 outputted from the plural laser light sources 21 are uniformly scattered within a specific effective range (FOV) in the space after beam shaping (beam shaping) by the diffractive optical element 22, so as to perform time-of-flight measurement.
However, a typical laser source is manufactured in a factory with a certain tolerance, which results in a difference of the central wavelength of the laser beam outputted from the laser source with the same specification, and the difference of the central wavelength can reach tens of nanometers (nm) due to the influence of the temperature in the usage environment. Since the diffractive optical element is very sensitive to the wavelength of the diffracted light incident thereon and has wavelength selectivity, the application of the diffractive optical element is limited by its diffractive nature.
In detail, the diffraction efficiency of a general diffractive optical element having a single-layer structure can be expressed mathematically as follows:
wherein λ is the wavelength of the laser beam incident on the diffractive optical element, λ0Eta (lambda) is the diffraction efficiency of the diffractive optical element for a wavelength lambda,
is the optical path difference (phase difference) at a wavelength of λ, h is the maximum height of the diffractive optical element, n (λ) and n (λ)0) For wavelength lambda and wavelength lambda, respectively, of the diffractive optical element0Refractive index of (1), nairFor air versus wavelength λ and wavelength λ0Is used as a refractive index of (1). Thus, when the wavelength λ of the laser beam incident on the diffractive optical element is the same as the design wavelength λ of the diffractive optical element0The theoretical value of diffraction efficiency can be expressed as sinc2{1-1}＝100％。
Referring to FIG. 3, a diffraction optical element with a single-layer structure is made of Polycarbonate (PC) material and has a design wavelength λ0The relationship between diffraction efficiency at each wavelength is shown in 436.8. As is clear from the above description and fig. 3, the diffractive optical element has a high diffraction efficiency (77.64%) only when the wavelength of the laser beam is 436.8, and the diffraction efficiency is smaller as the wavelength increases, that is, the diffractive optical element having a single-layer structure is very narrow in the usable wavelength range, and the wavelength λ of the laser beam incident on the diffractive optical element needs to be close to the design wavelength λ of the diffractive optical element0A better diffraction efficiency can be obtained.
In addition to this, the present invention is,diffractive optical element for zero order beams (0) of different wavelengthsthorder) diffraction efficiency is shown in fig. 4, which is a phenomenon (indicated by an arrow) that when the wavelength of the laser beam output from the laser light source is different from the design wavelength of the diffractive optical element, a strong zero-order beam effect (indicated by an arrow) as shown in fig. 5 is formed, or a phenomenon (indicated by an arrow) that causes a reduction in the signal-to-noise ratio (SNR) as shown in fig. 6 is caused. As described above, the conventional diffractive light projection device has room for improvement.
SUMMERY OF THE UTILITY MODEL
The to-be-solved technical problem of the utility model lies in, the aforesaid that exists to prior art is not enough, provides a diffraction light projection arrangement, can extend diffraction optical module to the incident usable wavelength range to light beam wherein, promotes the design degree of freedom of diffraction optical module.
The technical solution adopted by the present invention to solve the technical problem is to provide a diffractive light projection device, which comprises a light source and a diffractive optical module, wherein the light source is used for outputting a light beam; the diffraction optical module is used for the light beam to pass through to form diffraction light projected outwards and comprises a first diffraction optical element and a second diffraction optical element; the first diffractive optical element and the second diffractive optical element are arranged in a laminated mode and made of different materials respectively and used for extending a usable wavelength range of the light beam together.
Preferably, the first diffractive optical element has a first light incident surface and a first light emitting surface, and the second diffractive optical element has a second light incident surface and a second light emitting surface; the light beam sequentially passes through the first light incident surface, the first light emergent surface, the second light incident surface and the second light emergent surface to form the diffraction light projected outwards.
Preferably, the first light-emitting surface has a first surface structure, and the second light-incident surface has a second surface structure; wherein the first surface structure and the second surface structure are complementary in shape; or the first light incident surface has the first surface structure, and the second light emergent surface has the second surface structure; wherein the first surface structure and the second surface structure are complementary in shape.
Preferably, the first surface structure and the second surface structure are both stepped, and any two complementary steps of the first surface structure and the second surface structure have the same width.
Preferably, a distance is provided between the first light emitting surface and the second light incident surface.
Preferably, the available wavelength range is between a first wavelength and a second wavelength, and the first diffractive optical element has a first refractive index and a second refractive index for the first wavelength and the second wavelength respectively, and the second diffractive optical element has a third refractive index and a fourth refractive index for the first wavelength and the second wavelength respectively; wherein a maximum height of the first diffractive optical element and a maximum height of the second diffractive optical element satisfy the following relations:
wherein h is1And h2The maximum height of the first diffractive optical element and the maximum height, λ, of the second diffractive optical element, respectively1And λ2The first wavelength and the second wavelength, n1(λ1) And n1(λ2) The first and second refractive indices, n2(λ1) And n2(λ2) The third refractive index and the fourth refractive index are respectively.
Preferably, the first light-emitting surface is attached to the second light-entering surface.
Preferably, the available wavelength range is between a first wavelength and a second wavelength, and the first diffractive optical element has a first refractive index and a second refractive index for the first wavelength and the second wavelength respectively, and the second diffractive optical element has a third refractive index and a fourth refractive index for the first wavelength and the second wavelength respectively; wherein, the diffraction optical module satisfies the following relation:
wherein λ is1And λ2The first wavelength and the second wavelength, n1(λ1) And n1(λ2) The first and second refractive indices, n2(λ1) And n2(λ2) The third refractive index and the fourth refractive index are respectively.
Preferably, the diffractive light projection device is a diffractive light projection device for a stereo sensing system or a biometric system.
The utility model also provides a diffraction light projection device, which comprises a luminous source and a diffraction optical module, wherein the luminous source is used for outputting a light beam; the diffraction optical module is used for the light beam to pass through to form diffraction light projected outwards, and the diffraction optical module comprises a first diffraction optical element and a second diffraction optical element which are arranged in a laminated mode and made of different materials respectively; wherein, an available wavelength range of the light beam comprises a first wavelength and a second wavelength which is different from the first wavelength by more than fifty nanometers, and the difference of the diffraction efficiency of the diffraction optical module to any two wavelengths between the first wavelength and the second wavelength is less than five-zero percent.
Preferably, the first diffractive optical element has a first light incident surface and a first light emitting surface, and the second diffractive optical element has a second light incident surface and a second light emitting surface; the light beam sequentially passes through the first light incident surface, the first light emergent surface, the second light incident surface and the second light emergent surface to form the diffraction light projected outwards.
Preferably, the first light-emitting surface has a first surface structure, and the second light-incident surface has a second surface structure; wherein the shape of the first surface structure and the shape of the second surface structure are complementary; or the first light incident surface has the first surface structure, and the second light emergent surface has the second surface structure; wherein the first surface structure and the second surface structure are complementary in shape.
Preferably, the first surface structure and the second surface structure are both stepped, and any two complementary steps of the first surface structure and the second surface structure have the same width.
Preferably, a distance is provided between the first light emitting surface and the second light incident surface.
Preferably, the first diffractive optical element has a first refractive index and a second refractive index for the first wavelength and the second wavelength, respectively, and the second diffractive optical element has a third refractive index and a fourth refractive index for the first wavelength and the second wavelength, respectively; wherein a maximum height of the first diffractive optical element and a maximum height of the second diffractive optical element satisfy the following relations:
wherein h is1And h2The maximum height of the first diffractive optical element and the maximum height, λ, of the second diffractive optical element, respectively1And λ2The first wavelength and the second wavelength, n1(λ1) And n1(λ2) The first and second refractive indices, n2(λ1) And n2(λ2) Are respectively the third foldRefractive index and the fourth refractive index.
Preferably, the first light-emitting surface is attached to the second light-entering surface.
Preferably, the first diffractive optical element has a first refractive index and a second refractive index for the first wavelength and the second wavelength, respectively, and the second diffractive optical element has a third refractive index and a fourth refractive index for the first wavelength and the second wavelength, respectively; wherein, the diffraction optical module satisfies the following relation:
wherein λ is1And λ2The first wavelength and the second wavelength, n1(λ1) And n1(λ2) The first and second refractive indices, n2(λ1) And n2(λ2) The third refractive index and the fourth refractive index are respectively.
Preferably, the diffractive light projection device is a diffractive light projection device for a stereo sensing system or a biometric system.
The utility model discloses diffraction optical module of diffraction light projection arrangement adopts multilayer diffraction optical element's design to utilize multilayer diffraction optical element to have the characteristic of different refracting indexes to different wavelengths, extended diffraction optical module to the incident available wavelength scope to light beam wherein, and promoted diffraction optical module's design degree of freedom, possess the industrial utilization value in fact. Furthermore, the laminated diffractive optical elements are embedded and have a compact structure, and dirt such as dust and moisture are not easy to permeate.
Drawings
FIG. 1: is a conceptual diagram of the implementation of stereo sensing using structured light technology.
FIG. 2: is a conceptual diagram of the prior art using time-of-flight technology for stereo sensing.
FIG. 3: diffracted light of single-layer structureThe optical element is made of Polycarbonate (PC) material and has a design wavelength lambda0The relationship between diffraction efficiency at each wavelength is shown in 436.8.
FIG. 4: diffractive optical element of single-layer structure for zero-order light beams (0) of different wavelengthsthorder) diffraction efficiency.
FIG. 5: is a conceptual illustration of a single layer structure of a diffractive optical element resulting in a strong zero-order beam effect.
FIG. 6: is a conceptual diagram of a phenomenon in which a diffractive optical element of a single-layer structure causes a reduction in signal-to-noise ratio (SNR).
FIG. 7: is a schematic block diagram of a diffraction light projection device according to a first preferred embodiment of the present invention.
FIG. 8: is a conceptual diagram of the structure of the diffractive optical module shown in FIG. 7.
FIG. 9: is a schematic view of the structural concept of the diffractive optical module of the diffractive light projecting device of the present invention in a second preferred embodiment.
FIG. 10: is a schematic view of the structural concept of the diffractive optical module of the diffractive light projecting device of the present invention in a third preferred embodiment.
FIG. 11: the relationship between the diffraction efficiency of the diffractive optical module shown in FIG. 10 and the diffraction efficiency of the diffractive optical module for wavelengths between 436.8 nm and 633.7 nm is shown.
FIG. 12: the diffractive optical module of FIG. 10 is for a zero-order beam (0) of different wavelengths in one embodimentthorder) diffraction efficiency.
FIG. 13: is a conceptual diagram of the structure of the diffractive optical module according to a fourth preferred embodiment of the diffractive light projecting device of the present invention.
FIG. 14: is a schematic view of the structural concept of the diffractive optical module according to a fifth preferred embodiment of the diffractive light projection device of the present invention.
FIG. 15: is a schematic view of the structural concept of the diffractive optical module according to a sixth preferred embodiment of the diffractive light projection device of the present invention.
Detailed Description
Embodiments of the present invention will be further explained with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings and the description to refer to the same or like parts. In the drawings, the shape and thickness may be exaggerated for simplicity and convenience. It is to be understood that elements not specifically shown in the drawings or described in the specification are in a form known to those of ordinary skill in the art. Various changes and modifications may be made by one of ordinary skill in the art in light of the teachings of the present invention.
Referring to fig. 7 and 8, fig. 7 is a schematic block diagram of a diffractive light projection device according to a first preferred embodiment of the present invention, and fig. 8 is a schematic structural diagram of a diffractive optical module shown in fig. 7. The diffractive light projection device 3 includes a light source 31 and a diffractive optical module 32, wherein the light source 31 is used for outputting a light beam L31, alternatively, the light source 31 is a laser light source, but not limited thereto, and after the light source 31 outputs a light beam L31, the diffractive optical module 32 can allow the light beam L31 to pass through to form a diffractive light L32 which is projected outward.
Furthermore, the diffractive optical module 32 includes a first diffractive optical element 321 and a second diffractive optical element 322 stacked together, the first diffractive optical element 321 has a first light incident surface 3211 and a first light emitting surface 3212, and the second diffractive optical element 322 has a second light incident surface 3221 and a second light emitting surface 3222. When the light beam L31 output by the light source 31 enters the diffractive optical module 32, the light beam L31 sequentially passes through the first light incident surface 3211, the first light emitting surface 3212, the second light incident surface 3221 and the second light emitting surface 3222 to form a diffracted light L32 projecting outwards. The first light emitting surface 3212 has a plurality of first surface structures 32121A, the second light incident surface 3221 has a plurality of second surface structures 32211, and a shape of any one of the first surface structures 32121 is complementary to a shape of its corresponding second surface structure 32211.
In the preferred embodiment, a distance is provided between the first light emitting surface 3212 and the second light incident surface 3221, the first surface structure 32121 and the second surface structure 32211 are both in a step shape with four steps, and any two complementary steps of the first surface structure 32121 and the second surface structure 32211 have the same width. However, the above embodiments are only examples, and the number of the diffractive optical elements, the shape of the first surface structure and the shape of the second surface structure are not limited to the above embodiments, and those skilled in the art can make any equivalent design changes according to the practical application requirements.
It is to be noted that, in the present invention, the first diffractive optical element 321 and the second diffractive optical element 322 are made of different materials, and therefore have different refractive indexes for the same wavelength, and the main purpose is to jointly extend the usable wavelength range of the light beam L31 incident on the diffractive optical module 32, which will be described in further detail in the following embodiments. Preferably, but not limited thereto, based on the structural design of the diffractive optical module 32, the usable wavelength range of the light beam L31 exceeds fifty nanometers, and the difference between the diffraction efficiencies of the diffractive optical module 32 for any two wavelengths in the usable wavelength range is less than zero-point five percent.
Please refer to fig. 9, which is a schematic view illustrating a structural concept of a diffractive optical module according to a second preferred embodiment of the diffractive light projection apparatus of the present invention. The diffractive light projection device of the present preferred embodiment is substantially similar to that described in the first preferred embodiment, and will not be described herein again. The difference between the preferred embodiment and the aforementioned first preferred embodiment is that the first light emitting surface 4212 of the first diffractive optical element 421 of the diffractive optical module 42 is attached to the second light incident surface 4221 of the second diffractive optical element 422, and any first surface structure on the first light emitting surface 4212 and any second surface structure on the second light incident surface 4221 are in a two-step shape.
Furthermore, the diffraction efficiency of the diffractive optical module 42 of the preferred embodiment can be expressed by the following mathematical formula:
wherein λ is2The wavelength of the light beam L41 incident on the diffractive optical module 42 (regarded as the second wavelength in the present embodiment), λ1Is the design wavelength of the diffractive optical element 42 (considered as the first wavelength in this embodiment), η (λ)2) For the diffractive optical module 42 to be lambda for the wavelength2The efficiency of the diffraction at the time of diffraction,
the first light exiting surface 4212 and the second light entering surface 4221 are continuous in phase and have a wavelength λ2The optical path difference (phase difference) between the first light emitting surface 4212 and the second light incident surface 4221 is a second order phase in the preferred embodiment
Is modified into
And Level 2. H is the maximum height of the diffractive optical module 42 (i.e., the first diffractive optical element and the second diffractive optical element share the same height), and n is1(λ1) And n1(λ2) The first diffractive optical element 421 for the wavelength λ1And wavelength lambda2Refractive index (n) of1(λ1) And n1(λ2) In the present embodiment, referred to as the first refractive index and the second refractive index, respectively), n2(λ1) And n2(λ2) For the wavelength λ of the second diffractive optical element 422, respectively1And wavelength lambda2Refractive index (n) of2(λ1) And n2(λ2) Respectively considered as the third refractive index and the fourth refractive index in the present embodiment).
From the above description, when the diffractive optical module 42 satisfies the following relation, the theoretical value of the diffraction efficiency can be expressed as sinc2{1-1}＝100％：
In detail, when the first wavelength λ1Divided by a second wavelength lambda2Ratio of (lambda)1/λ2) Same as the first diffractive optical element 421 and the second optical element 422 for the first wavelength λ1Refractive index difference (n) of1(λ1)-n2(λ1) Divided by the first diffractive optical element 421 and the second diffractive optical element 422 for the second wavelength λ2Refractive index difference (n) of1(λ2)-n2(λ2) In time, the diffractive optical module 42 for the first wavelength λ1And a second wavelength lambda2All have diffraction efficiencies of 100% theoretical values, and the diffractive optical module 42 has a first wavelength λ1And a second wavelength lambda2Other wavelengths in between can also be kept at a better diffraction efficiency, i.e. the usable wavelength range of the diffractive optical module 42 at least includes the first wavelength λ1To a second wavelength lambda2In the middle range.
However, in order to make the first wavelength λ1Divided by a second wavelength lambda2Ratio of (lambda)1/λ2) The same as the first diffractive optical element 421 and the second diffractive optical element 422 for the first wavelength λ1Refractive index difference (n) of1(λ1)-n2(λ1) Divided by the first diffractive optical element 421 and the second diffractive optical element 422 for the second wavelength λ2Refractive index difference (n) of1(λ2)-n2(λ2) The choice of material for the first diffractive optical element 421 and the choice of material for the second optical element 422 will be greatly limited. Accordingly, the present invention also provides the following diffractive optical module 52.
Please refer to fig. 10, which is a schematic view illustrating a structural concept of a diffractive optical module according to a third preferred embodiment of the diffractive light projection apparatus of the present invention. The diffractive optical module of the present preferred embodiment is substantially similar to that described in the first preferred embodiment, and will not be described herein again. The difference between the present preferred embodiment and the foregoing first preferred embodiment is that any one of the first surface structures on the first light-emitting surface 5212 of the first diffractive optical element 521 and any one of the second surface structures on the second light-entering surface 5221 of the second diffractive optical element 522 are stepped.
Furthermore, the diffraction efficiency of the diffractive optical module 52 of the preferred embodiment can be expressed by the following mathematical formula:
where λ is the wavelength of the light beam L51 incident on the diffractive optical module 52, η (λ) is the diffraction efficiency of the diffractive optical module 52 for the wavelength λ,
the optical path difference (phase difference) when the first light emitting surface 5212 and the second light incident surface 5221 have continuous phase and the wavelength is λ, and the first light emitting surface 5212 and the second light incident surface 5221 in the preferred embodiment have second-order phase, so the first light emitting surface 5212 and the second light incident surface 5221 have second-order phase
Is modified into
And Level 2. And, h1And h2The maximum height of the first diffractive optical element 521 and the maximum height of the second diffractive optical element 522, n1(lambda) and n2(λ) is a refractive index of the first diffractive optical element 521 and the second diffractive optical element 522 with respect to the wavelength λ.
As can be seen from the above description, when h is1·(n1(λ)-1)-h2·(n2When (λ) -1) ═ λ, the theoretical value of diffraction efficiency can be expressed as sinc2{1-1}＝100 percent. Thus, when the maximum height h of the first diffractive optical element 521 is set1And the maximum height h of the second diffractive optical element 5222When the following relation is satisfied, the wavelength λ of the light beam L51 incident on the diffractive optical module 52 is λ1(referred to as the first wavelength in this embodiment) and λ2The diffraction efficiency (considered as the second wavelength in the present embodiment) is 100%, and the diffractive optical module 52 has a first wavelength λ1And a second wavelength lambda2Other wavelengths in between can also be maintained at a better diffraction efficiency, i.e., the usable wavelength range of the diffractive optical module 52 includes at least the first wavelength λ1To a second wavelength lambda2In the range of (A) to (B):
wherein n is1(λ1) And n1(λ2) For a first wavelength λ for the first diffractive optical element 521, respectively1Is (referred to as the first refractive index in the present embodiment) and the first diffractive optical element 521 has a refractive index for the second wavelength λ2Is (is) a refractive index (referred to as a second refractive index in this embodiment), n2(λ1) And n2(λ2) For the first wavelength λ for the second diffractive optical element 522, respectively1Is (referred to as a third refractive index in the present embodiment) and the second diffractive optical element 522 for the second wavelength λ2Is (is regarded as a fourth refractive index in the present embodiment).
Two embodiments of the diffractive optical module according to the preferred embodiment are illustrated below. In the first embodiment, the usable wavelength range of the diffractive optical module 52 for the incident light beam L51 at least includes 436.8 nm (the first wavelength λ1) To 633.7 nm (first wavelength lambda)2) In the range between, the first diffractive optical element 521 uses a polymethyl methacrylate (PMMA) material for the first wavelength λ1Has a refractive index (first refractive index) of 1.502 and λ for a second wavelength2Has a refractive index of 1.489 (second refractive index), and the second diffractive optical element 522 uses a Polycarbonate (PC) material for the first wavelength λ1Has a refractive index (third refractive index) of 1.611 and λ for a second wavelength2Has a refractive index (fourth refractive index) of 1.58, is the maximum height h of the first diffractive optical element 5211Can be designed to be 9.1461 micrometers (μm) with the maximum height h of the second diffractive optical element 5222Can be designed to be 7.1548 microns.
Wherein, based on the above design, the diffractive optical module 52 is designed for 436.8 nm (the first wavelength λ)1) To 633.7 nm (first wavelength lambda)2) The relationship between the diffraction efficiency of each wavelength is schematically shown in FIG. 11, and the diffraction optical module is for 436.8 nm (the first wavelength λ1) To 633.7 nm (first wavelength lambda)2) Between the zero order beam (0) of each wavelengththorder) diffraction efficiency is shown in fig. 12. As can be seen from comparing fig. 3 and 11 and fig. 4 and 12, the diffraction optical module 52 of the present invention greatly increases the usable wavelength range of the light beam L51 incident therein.
Furthermore, in the second embodiment, in order to make the available wavelength range of the diffraction optical module 52 for the incident light beam L51 at least include 486.1 nm (the first wavelength λ1) To 587.6 nm (first wavelength lambda)2) In the range between, the first diffractive optical element 521 adopts the wavelength λ for the first wavelength1Has a refractive index of 1.6848 (first refractive index) and for a second wavelength λ2A material having a refractive index of 1.6613 (second refractive index), and the second diffractive optical element 522 employs a material for the first wavelength λ1Has a refractive index of 1.55134 (third refractive index) and λ for a second wavelength2A material having a refractive index of 1.5445 (fourth refractive index) is such that the maximum height h of the first diffractive optical element 521 is1Can be designed as7.1667 microns and the maximum height h of the second diffractive optical element 5222Can be designed to be 9.7831 microns.
It is to be understood that the above description is only exemplary and that those skilled in the art can make various modifications and changes according to the actual application. For example, although in the diffractive optical module 32 of the first preferred embodiment, the first surface structure 32121 and the second surface structure 32211 are respectively formed on the first light-emitting surface 3212 of the first diffractive optical element 321 and the second light-entering surface 3221 of the second diffractive optical element 322, the first surface structure 32121 ' and the second surface structure 32211 ' may be alternatively designed to be respectively formed on the first light-entering surface 3211 ' of the first diffractive optical element 321 ' and the second light-emitting surface 3222 ' of the second diffractive optical element 322 ', which is the diffractive optical module 32 ' shown in fig. 13.
For another example, although the first surface structure and the second surface structure are respectively formed on the first light-emitting surface 4212 of the first diffractive optical element 421 and the second light-entering surface 4221 of the second diffractive optical element 422 in the diffractive optical module 42 of the second preferred embodiment, the first surface structure and the second surface structure can be alternatively designed to be respectively formed on the first light-entering surface 4211 ' of the first diffractive optical element 421 ' and the second light-emitting surface 4222 ' of the second diffractive optical element 422 ', which is the diffractive optical module 42 ' shown in fig. 14.
For example, although the first surface structure and the second surface structure are respectively formed on the first light-emitting surface 5212 of the first diffractive optical element 521 and the second light-entering surface 5221 of the second diffractive optical element 522 in the diffractive optical module 52 of the third preferred embodiment, the first surface structure and the second surface structure can be alternatively designed to be respectively formed on the first light-entering surface 5211 ' of the first diffractive optical element 521 ' and the second light-emitting surface 5222 ' of the second diffractive optical element 522 ', as shown in the diffractive optical module 52 ' shown in fig. 15.
According to the above description, the diffractive optical module of the diffractive light projection apparatus of the present invention adopts the design of the multilayer diffractive optical element, and utilizes the characteristic that the multilayer diffractive optical element has different refractive indexes for different wavelengths and each diffractive optical element has the respective maximum height, so as to extend the usable wavelength range of the diffractive optical module for the light beam incident therein, and improve the design freedom of the diffractive optical module, thereby achieving industrial utility value. Preferably, the stacked diffractive optical elements are embedded and have a compact structure, which has the advantages of being less prone to dirt such as dust and moisture infiltration.
In particular, the diffraction light projection device of the present invention can be applied to a stereo sensing system or a biometric system (e.g., a human face recognition system), but not limited thereto, and since the usable wavelength range of the light beam incident to the diffraction optical module is extended, when the wavelength of the light beam projected by the diffraction light projection device drifts or does not conform to the design with the wavelength, the sensing quality of the stereo sensing system or the recognition quality of the biometric system is not affected, for example, the strong zero-order light effect (indicated by the arrow) shown in fig. 5 or the phenomenon of the reduction of the signal-to-noise ratio (SNR) (indicated by the arrow) shown in fig. 6 can be improved.
The above description is only for the preferred embodiment of the present invention and should not be construed as limiting the scope of the claims, therefore, all other equivalent changes and modifications that do not depart from the spirit of the present invention should be included in the scope of the claims.
Claims (18)
1. A diffractive light projection apparatus, comprising:
a light source for outputting a light beam; and
the diffraction optical module is used for forming diffraction light projected outwards by the light beam, and comprises a first diffraction optical element and a second diffraction optical element; the first diffractive optical element and the second diffractive optical element are arranged in a laminated mode and made of different materials respectively and used for extending a usable wavelength range of the light beam together.
2. The diffractive light projection device according to claim 1, wherein the first diffractive optical element has a first light incident surface and a first light emitting surface, and the second diffractive optical element has a second light incident surface and a second light emitting surface; the light beam sequentially passes through the first light incident surface, the first light emergent surface, the second light incident surface and the second light emergent surface to form the diffraction light projected outwards.
3. The diffractive light projection device according to claim 2, wherein the first light exiting surface has a first surface structure and the second light entering surface has a second surface structure; wherein the first surface structure and the second surface structure are complementary in shape; or
The first light incident surface has the first surface structure, and the second light emergent surface has the second surface structure; wherein the first surface structure and the second surface structure are complementary in shape.
4. The diffractive light projection device according to claim 3, wherein the first and second surface structures are both stepped, and any two complementary steps of the first and second surface structures have the same width.
5. The diffractive light projection device according to claim 2, wherein a distance is provided between the first light exiting surface and the second light entering surface.
6. The diffractive light projection device according to claim 5, wherein the available wavelength range is between a first wavelength and a second wavelength, and the first diffractive optical element has a first refractive index and a second refractive index for the first wavelength and the second wavelength, respectively, and the second diffractive optical element has a third refractive index and a fourth refractive index for the first wavelength and the second wavelength, respectively; wherein a maximum height of the first diffractive optical element and a maximum height of the second diffractive optical element satisfy the following relations:
wherein h is1And h2The maximum height of the first diffractive optical element and the maximum height, λ, of the second diffractive optical element, respectively1And λ2The first wavelength and the second wavelength, n1(λ1) And n1(λ2) The first and second refractive indices, n2(λ1) And n2(λ2) The third refractive index and the fourth refractive index are respectively.
7. The diffractive light projection device according to claim 2, wherein the first light exit surface is bonded to the second light entrance surface.
8. The diffractive light projection device according to claim 7, wherein the available wavelength range is between a first wavelength and a second wavelength, and the first diffractive optical element has a first refractive index and a second refractive index for the first wavelength and the second wavelength, respectively, and the second diffractive optical element has a third refractive index and a fourth refractive index for the first wavelength and the second wavelength, respectively; wherein, the diffraction optical module satisfies the following relation:
wherein λ is1And λ2The first wavelength and the second wavelength, n1(λ1) And n1(λ2) Are respectively asThe first and second refractive indices, n2(λ1) And n2(λ2) The third refractive index and the fourth refractive index are respectively.
9. The diffractive light projection device according to claim 1, wherein the diffractive light projection device is a diffractive light projection device for a stereo sensing system or a biometric system.
10. A diffractive light projection apparatus, comprising:
a light source for outputting a light beam; and
the diffraction optical module is used for allowing the light beam to pass through to form diffraction light projected outwards and comprises a first diffraction optical element and a second diffraction optical element which are arranged in a laminated mode and made of different materials respectively; wherein, an available wavelength range of the light beam comprises a first wavelength and a second wavelength which is different from the first wavelength by more than fifty nanometers, and the difference of the diffraction efficiency of the diffraction optical module to any two wavelengths between the first wavelength and the second wavelength is less than five-zero percent.
11. The diffractive light projection device according to claim 10, wherein the first diffractive optical element has a first light incident surface and a first light emitting surface, and the second diffractive optical element has a second light incident surface and a second light emitting surface; the light beam sequentially passes through the first light incident surface, the first light emergent surface, the second light incident surface and the second light emergent surface to form the diffraction light projected outwards.
12. The diffractive light projection device according to claim 11, wherein the first light exiting surface has a first surface structure and the second light entering surface has a second surface structure; wherein the shape of the first surface structure and the shape of the second surface structure are complementary; or
The first light incident surface has the first surface structure, and the second light emergent surface has the second surface structure; wherein the first surface structure and the second surface structure are complementary in shape.
13. The diffractive light projection device according to claim 12, wherein the first surface structure and the second surface structure are both stepped, and any two complementary steps of the first surface structure and the second surface structure have the same width.
14. The diffractive light projection device according to claim 11, wherein a distance is provided between the first light exiting surface and the second light entering surface.
15. The diffractive light projection device according to claim 14, wherein the first diffractive optical element has a first refractive index and a second refractive index for the first wavelength and the second wavelength, respectively, and the second diffractive optical element has a third refractive index and a fourth refractive index for the first wavelength and the second wavelength, respectively; wherein a maximum height of the first diffractive optical element and a maximum height of the second diffractive optical element satisfy the following relations:
wherein h is1And h2The maximum height of the first diffractive optical element and the maximum height, λ, of the second diffractive optical element, respectively1And λ2The first wavelength and the second wavelength, n1(λ1) And n1(λ2) The first refractive index and the second refractive indexRate, n2(λ1) And n2(λ2) The third refractive index and the fourth refractive index are respectively.
16. The diffractive light projection device according to claim 11, wherein the first light exit surface is bonded to the second light entrance surface.
17. The diffractive light projection device according to claim 16, wherein the first diffractive optical element has a first refractive index and a second refractive index for the first wavelength and the second wavelength, respectively, and the second diffractive optical element has a third refractive index and a fourth refractive index for the first wavelength and the second wavelength, respectively; wherein, the diffraction optical module satisfies the following relation:
wherein λ is1And λ2The first wavelength and the second wavelength, n1(λ1) And n1(λ2) The first and second refractive indices, n2(λ1) And n2(λ2) The third refractive index and the fourth refractive index are respectively.
18. The diffractive light projection device according to claim 10, wherein the diffractive light projection device is a diffractive light projection device for a stereo sensing system or a biometric system.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| TW108214855U TWM592976U (en) | 2019-11-08 | 2019-11-08 | Diffraction light projecting device |
| TW108214855 | 2019-11-08 |
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| Publication Number | Publication Date |
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| CN211928320U true CN211928320U (en) | 2020-11-13 |
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|---|---|---|---|---|
| CN112782863A (en) * | 2019-11-08 | 2021-05-11 | 高准精密工业股份有限公司 | Diffraction light projection device |
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- 2019-11-08 TW TW108214855U patent/TWM592976U/en unknown
- 2019-11-15 CN CN201921978307.3U patent/CN211928320U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112782863A (en) * | 2019-11-08 | 2021-05-11 | 高准精密工业股份有限公司 | Diffraction light projection device |
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| TWM592976U (en) | 2020-04-01 |
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