Optical combiner and optical device using the same

Abstract

An optical device includes a light-emitting element and an optical combiner. The light-emitting element is configured to emit invisible light. The optical combiner is disposed in the optical path of the invisible light. The optical combiner includes a series of phosphors. The series of phosphors is configured to emit visible light when excited by the invisible light.

Description

[Technical Field]

[0001] This disclosure relates to an optical combiner and an optical device using the same. [Previous Technology]

[0002] Current augmented reality (AR) devices employ various optical elements, such as mirrors and lenses, which are typically colorless and transparent, thus having minimal impact on the color of the original image source, aside from inherent element light loss. However, in AR devices using waveguide elements, the inherent wavelength and angle selectivity of these waveguides present challenges for color reproduction. Specifically, as an input image passes through a waveguide, light of different wavelengths is diffracted at different angles and efficiencies due to the diffraction / holographic structure. Theoretically, shorter wavelengths, such as blue light, diffract at smaller angles, while longer wavelengths, such as red light, diffract at larger angles. Even with narrow-band monochromatic light sources, this difference in diffraction angles and efficiencies across the color spectrum results in uneven brightness distribution and color scattering (color fringing). Therefore, when displaying a white image on a waveguide-based AR device, a gradient rainbow-like color shift and non-uniform brightness can be easily observed, typically transitioning from blue to red from one side of the viewing area.

[0003] A common traditional method is to adjust the energy ratio of red, green, and blue light sources in an image projector to compensate for different diffraction efficiencies and approximate the mixing of white light. For example, if the initial white light energy ratio of red, green, and blue light is 3:6:1, and the peak diffraction efficiencies are 3%, 8%, and 2%, respectively, the light source might be adjusted to a ratio of 2:1.5:1 to maintain the energy balance of white light after diffraction. However, the fundamental limitation of this method lies in the least efficient color component (e.g., blue light in the example), forcing the other colors to be adjusted proportionally, resulting in a significant reduction in the overall brightness of the final displayed image. Furthermore, AR devices typically employ high-transmittance optics, including waveguides, which allow ambient light from the real-world environment to pass through and reach the user's eyes. This ambient light can superimpose with the colors of the AR image, causing color distortion. For example, using an AR device in a yellow-lit environment may cause the AR image to appear yellow. Traditional color correction methods that focus solely on adjusting the virtual image light source often ignore or are significantly affected by this ambient light, thus limiting their effectiveness in achieving accurate and uniform color perception.

[0004] Therefore, the industry urgently needs to provide an optical combiner and an optical device using it that can solve the various problems mentioned above. [Summary of the Invention]

[0005] One aspect of this disclosure is to provide an optical combiner that can effectively solve the aforementioned problems and an optical device using the same.

[0006] According to one embodiment of the present disclosure, an optical combiner includes a light-transmitting substrate and a series of phosphors. The series of phosphors are disposed on the light-transmitting substrate and configured to emit visible light when excited by invisible light.

[0007] In one embodiment of this disclosure, the series of phosphors are distributed within a light-transmitting substrate.

[0008] In one embodiment of this disclosure, the series of phosphors are disposed on one edge of a light-transmitting substrate.

[0009] In one embodiment of this disclosure, the invisible light is infrared light.

[0010] In one embodiment of this disclosure, the infrared light has a wavelength of about 940 nm.

[0011] In one embodiment of this disclosure, the light-transmitting substrate is a diffraction structure or a reflection structure.

[0012] In one embodiment of this disclosure, the optical combiner further includes another series of phosphors. The other series of phosphors is disposed on a light-transmitting substrate and configured to emit another visible light when excited by another invisible light.

[0013] According to one embodiment of the present disclosure, an optical device includes a light-emitting element and an optical combiner. The light-emitting element is configured to emit invisible light. The optical combiner is disposed in the optical path of the invisible light. The optical combiner includes a series of phosphors. The series of phosphors is configured to emit visible light when excited by the invisible light.

[0014] In one embodiment of this disclosure, the optical combiner further includes a light-transmitting substrate. The series of phosphors are distributed within the light-transmitting substrate.

[0015] In one embodiment of this disclosure, the optical combiner further includes a light-transmitting substrate. The series of phosphors are disposed on one edge of the light-transmitting substrate.

[0016] In one embodiment of this disclosure, the invisible light is infrared light.

[0017] In one embodiment of this disclosure, the infrared light has a wavelength of about 940 nm.

[0018] In one embodiment of this disclosure, the optical combiner further includes a light-transmitting substrate. The light-transmitting substrate is a diffraction structure or a reflection structure.

[0019] In one embodiment of this disclosure, the optical device further includes another light-emitting element configured to emit another invisible image light. An optical combiner is disposed in the optical path of this other invisible light and further includes another series of phosphors. This other series of phosphors is configured to emit another visible light when excited by the other invisible light.

[0020] In one embodiment of this disclosure, the optical device further includes a controller configured to individually control the light-emitting element and another light-emitting element.

[0021] In one embodiment of this disclosure, the optical device further includes a color light sensor and a controller. The color light sensor is configured to generate a sensing signal in response to sensing ambient light. The controller is configured to control a light-emitting element based on the sensing signal.

[0022] Therefore, in the optical combiner and optical device disclosed herein, a series of phosphors configured to emit visible light upon excitation by invisible light are disposed on or distributed within the light-transmitting substrate of the optical combiner. By emitting visible light upon excitation by invisible light, the color of the light perceived by the user can be adjusted and enhanced, thereby achieving color balance and improving the visual quality of the augmented reality experience. By employing one or more series of phosphors that respond to different invisible light emitting elements, various color adjustments and effects can be achieved, and even dynamic color control may be possible. In other words, this disclosure employs an optical combiner containing phosphors that, using additive color mixing, can effectively manage the color of virtual images superimposed on real-world scenes after being excited by invisible light. Therefore, this disclosure effectively solves the problems encountered in traditional optical devices, such as color distortion of virtual images and the difficulty in achieving the required color balance. These traditional optical devices rely solely on adjusting the light-emitting elements of virtual images or are significantly affected by ambient light, thereby improving the color fidelity and overall immersion of users in augmented reality experiences. In addition, using invisible light to excite phosphors can minimize the visibility of the light-emitting elements themselves and prevent unnecessary visual interference.

[0023] The above description is only used to illustrate the problem to be solved by this disclosure, the technical means to solve the problem, and the effects produced, etc. The specific details of this disclosure will be described in detail in the following implementation method and related figures.

Implementation Method

[0025] Specific embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Wherever possible, the same element symbols in the drawings and description will be used to refer to the same or similar components. However, the specific structural and functional details disclosed herein are for illustrative purposes only and may therefore be implemented in many alternative forms, and should not be construed as being limited to the illustrative embodiments described herein. Therefore, it should be understood that the illustrative embodiments are not intended to be limited to the specific forms disclosed; rather, the illustrative embodiments are intended to cover all modifications, equivalents, and alternatives falling within the scope of this disclosure.

[0026] Refer to Figure 1. Figure 1 is a schematic diagram illustrating an optical device 100 according to an embodiment of the present disclosure. As shown in Figure 1, in this embodiment, the optical device 100 can be used in an augmented reality device, which may be implemented as, but is not limited to, a pair of glasses or other wearable display devices. Specifically, the optical device 100 includes two optical combiners 110, an image projector 120, a temple 130, and a connecting member 140. The connecting member 140 is connected between the optical combiners 110. The temple 130 is connected to an edge of one of the optical combiners 110. The image projector 120 is disposed on the side of the temple 130 adjacent to the optical combiner 110. The optical device 100 may include another temple 130 (not shown) connected to the edge of the other optical combiner 110. The main function of each optical combiner 110 is to overlay a virtual image VI generated by the image projector 120 onto the real-world scene viewed by the user through the optical combiner 110.

[0027] Refer to Figure 2. Figure 2 is a schematic diagram illustrating the optical combiner 110 in Figure 1. As shown in Figure 2, and referring to Figure 1, in this embodiment, the image projector 120 is configured to emit image light L1 toward the optical combiner 110. The optical combiner 110 is disposed in the optical path of the image light L1. The optical combiner 110 includes a light-transmitting substrate 111 and a series of phosphors 112. The series of phosphors 112 are disposed on the light-transmitting substrate 111. The optical device 100 further includes a light-emitting element 150. The light-emitting element 150 is configured to emit invisible light. The series of phosphors 112 are configured to emit visible light when excited by the invisible light. Specifically, in this embodiment, the series of phosphors 112 are distributed within the light-transmitting substrate 111. In this way, the image light L1 that enters and propagates in the optical combiner 110 will combine with the visible light generated by the series of phosphors 112 and be output as image light L1', and the ambient light L2 will also combine with the visible light generated by the series of phosphors 112 after passing through the optical combiner 110 and be output as ambient light L2'.

[0028] In some embodiments, the invisible light emitted by the light-emitting element 150 is infrared light. For example, the wavelength of infrared light is about 940 nm, but this disclosure is not limited thereto. This particular choice of technology has significant advantages in terms of both functionality and practicality, as detailed below.

[0029] First, infrared light of approximately 940 nm is used, which is invisible to the human eye. This characteristic is crucial in applications where the user's visual experience must not be affected by the device's operating mechanism, such as in augmented reality glasses. The reason for using invisible light (infrared) with a wavelength of approximately 940 nm is to avoid seeing visible bright spots that may distract the user or reduce the quality of the augmented reality experience. Since the image light L1 output by the image projector 120 is very weak and difficult to view directly, this disclosure discloses a method of generating a brighter image light source by exciting phosphors to emit light with invisible light.

[0030] Secondly, by selecting a specific infrared wavelength of approximately 940 nm, the phosphors 112 in this series can be precisely and efficiently excited. The phosphorescent materials are designed to absorb light within a specific spectral range and then emit light at different (typically visible) wavelengths. Selecting an excitation source whose wavelength closely matches the absorption spectrum of the chosen phosphor ensures optimal energy transfer, resulting in brighter and more efficient visible light emission. This precision contributes to the fidelity and clarity of the virtual image (VI) projected onto the user.

[0031] Third, using an invisible infrared light source of approximately 940 nm can reduce interference from ambient visible light. If the series of phosphors 112 are excited using a visible light source, natural or artificial light in the environment may accidentally trigger the series of phosphors 112, causing unnecessary light emission or color shift in the virtual image VI. Excitation with invisible light can prevent real-world light from exciting the series of phosphors 112, or prevent the image light L1 used to display the virtual image VI from exciting the series of phosphors 112. This is crucial for maintaining the integrity and stability of the augmented reality display under various lighting conditions, ensuring that virtual elements are always presented as expected, regardless of the surrounding environment.

[0032] Please refer to Figure 3. Figure 3 is a schematic diagram illustrating additive color mixing. As shown in Figure 3, additive color mixing, also known as RGB color mixing, is based on the principle of mixing light of different wavelengths. The three primary colors for additive color mixing are red, green, and blue. When red light and green light are mixed, yellow light is produced; when green light and blue light are mixed, cyan light is produced; and when blue light and red light are mixed, magenta light is produced. When these three primary colors are mixed additively in appropriate proportions, they will produce white light.

[0033] In traditional augmented reality devices, regardless of whether the color light source of the image unit comes from LED, laser, LEDoS or OLEDoS, its color mixing theory is additive color mixing. For example, [λR (255)+λG (255)+λB (255)] makes the image ultimately display a white screen. Similarly, since augmented reality devices can directly see through the real world environment, natural light or artificial ambient light is also transmitted to the human eye through additive color mixing. As can be seen from the above discussion, augmented reality devices must simultaneously satisfy the transmission of virtual images and real world environment scenes. Therefore, they are usually described by light intensity formula and image intensity contrast formula respectively: Ivision= Ivirtual image+ Ireal world scene(1) Contrast ratio= Ivirtual image / (Ivirtual image+ Ireal world scene) (2) Where Ivision is the total light intensity, Ivirtual image is the light intensity of the virtual image, and Ireal world scene is the light intensity of the real world scene.

[0034] In this disclosure, light intensity is further subdivided into visible light color intensities Iλ, such as Ired, Igreen, and Iblue, where the red wavelength is approximately 620 nm to 750 nm, the green wavelength is approximately 495 nm to 570 nm, and the blue wavelength is approximately 450 nm to 475 nm. Since the visible light wavelength is approximately 380 nm to 750 nm, this disclosure is not limited to these three color intensities. By applying the above visible light color intensities to virtual images and real-world scenes, the intensity distribution of each color light can be analyzed separately.

[0035] Next, additive color mixing is introduced into the optical device 100. For example, when a series of phosphors 112 that emit yellow light when excited are uniformly doped into the light-transmitting substrate 111 of the optical combiner 110 and excited by a light-emitting element 150 configured to provide approximately 940 nm invisible light, the optical combiner 110 will act as a light source emitting a yellow spectral band. Therefore, the color of the virtual image VI projected through the optical combiner 110 will be additively mixed with the yellow light produced by the series of phosphors 112. Similarly, the real-world scene viewed through the optical combiner 110 will be superimposed with a yellow hue. The overall methodological characteristics can be explained as follows: Iλ *(virtual image)= Iλ (virtual image)+ Iλ (combiner) (3) Iλ *(real world scene)= Iλ (real world scene)+ Iλ (combiner) (4) Ivision= Ivirtual image+ Ireal world scene (5)

[0036] In some other embodiments, when the series of phosphors 112, which emit magenta light upon excitation, are uniformly doped within the light-transmitting substrate 111 of the optical combiner 110 and excited by a light-emitting element 150 configured to provide invisible light of approximately 940 nm or other wavelengths, the optical combiner 110 serves as a light source emitting a magenta spectral band. Magenta is a mixture of red and blue light. When the white image light L1 emitted by the image projector 120 is transmitted to the human eye through the optical combiner 110, the colors of the virtual image VI in the red and blue light bands are enhanced through additive color mixing. Simultaneously, the red and blue light bands of the ambient light L2' of the real-world scene are also enhanced. Therefore, when a user views the virtual image VI, after the red and blue layers are enhanced, he / she can see the white light image content. If the virtual image VI is a magenta image (e.g., a peony), the image will be more vivid.

[0037] In the embodiment shown in Figure 1, when the virtual image VI is not projected, the optical device 100 can be used solely to enhance the color wavelengths of the ambient scene, much like a pair of photochromic glasses. In this embodiment, the optical device 100 further includes a color sensor 160. The color sensor 160 is configured to detect and read the color level or color temperature of the ambient light L2 in the real world, and then provide a signal to a system (e.g., a controller 170 shown in Figure 6, which may be included in the optical device 100 in Figure 1) to determine whether to automatically trigger the light-emitting element 150. In some other embodiments, the light-emitting element 150 can be manually triggered to excite the series of phosphors 112.

[0038] As shown in Figures 1 and 2, in this embodiment, the light-transmitting substrate 111 of the optical combiner 110 has a diffraction structure, but this disclosure is not limited thereto.

[0039] Please refer to Figure 4. Figure 4 is a schematic diagram illustrating an optical device 200 according to another embodiment of this disclosure. As shown in Figure 4, in this embodiment, the optical device 200 includes two optical combiners 210, an image projector 120, a lens 130, a connecting member 140, two light-emitting elements 150, and a color sensor 160, wherein the image projector 120, lens 130, connecting member 140, light-emitting elements 150, and color sensor 160 are the same as those in the embodiment shown in Figure 1. Therefore, the relevant descriptions of these components can be found in the preceding paragraphs and will not be repeated here for the sake of simplicity.

[0040] It should be noted that the light-transmitting substrate 211 of the optical combiner 210 is a reflective structure in which the series of phosphors 112 are distributed. Unlike the embodiment shown in Figure 1, in this embodiment, the virtual image VI is reflected to the human eye by the optical combiner 210. Furthermore, since the optical combiner 210 still retains the mechanism of exciting the series of phosphors 112 through invisible light to generate a color gradient, the intensity and energy of the visible light color gradient from the series of phosphors 112 can still be superimposed on the colors of the virtual image VI and the real-world scene, ultimately producing display image content with an enhanced color layer.

[0041] Please refer to Figure 5. Figure 5 is a schematic diagram illustrating an optical device 300 according to another embodiment of the present disclosure. As shown in Figure 5, in this embodiment, the optical device 300 includes an optical combiner 310 and a light-emitting element 150. The optical combiner 310 includes a light-transmitting substrate 111 and a series of phosphors 312a. The series of phosphors 312a is disposed on one edge of the light-transmitting substrate 111 (i.e., the upper edge of the light-transmitting substrate 111 in Figure 5). The series of phosphors 312a may be the same as the series of phosphors 112 in the embodiments of Figures 1 and 2. Therefore, the series of phosphors 312a is configured to be excited by the invisible light emitted by the light-emitting element 150, and thereby emit the aforementioned type of visible light.

[0042] As shown in Figure 5, in this embodiment, the optical device 300 further includes a plurality of light-emitting elements 350. The light-emitting elements 350 are configured to emit another type of invisible light. An optical combiner 310 is disposed in the optical path of this other type of invisible light and further includes another series of phosphors 312b. This series of phosphors 312b is disposed at another edge of the light-transmitting substrate 111 (i.e., the right edge of the light-transmitting substrate 111 in Figure 5). This series of phosphors 312b is configured to emit another type of visible light when excited by the other type of invisible light. Through the additional light-emitting elements 350 and the corresponding series of phosphors 312b, this disclosure enables a wider range of color rendering capabilities or specific color correction functions. For example, the light-emitting element 150 may emit infrared light with a first wavelength (e.g., about 940 nm) to excite the series of phosphors 312a to produce yellow light, while the light-emitting element 350 may emit infrared light with a second different wavelength (e.g., about 850 nm) to excite the series of phosphors 312b to produce blue light. Furthermore, it can be seen that this disclosure is not limited to using a continuous light-emitting structure (i.e., light-emitting element 150), but can also use a discontinuous light-emitting structure (i.e., light-emitting element 350).

[0043] By independently or simultaneously controlling the light-emitting elements 150 and 350, richer colors can be mixed or presented in the virtual image VI, or precise color adjustments can be performed for specific application scenarios. This design can also more flexibly adjust the color performance of the virtual image VI by controlling the excitation intensity of different invisible lights to respond to changes in ambient light L2, further enhancing the visual quality for users of augmented reality experiences.

[0044] Please refer to Figure 6. Figure 6 is a functional block diagram illustrating the optical device 300 in Figure 5. As shown in Figure 6, in this embodiment, the optical device 300 may further include the same color sensor 160 and controller 170 as in the embodiments of Figures 1 and 2. The color sensor 160 is configured to generate a sensing signal in response to sensing ambient light L2. The controller 170 is configured to individually control the light-emitting elements 150 and 350 according to the sensing signal, thereby achieving different color effects, such as a theater mode.

[0045] Please refer to Figure 7. Figure 7 is a partial schematic diagram illustrating the optical combiner 110 in Figure 2. As shown in Figure 7, in this embodiment, the light-transmitting substrate 111 of the optical combiner 110 includes at least one holographic grating 1111. The holographic grating 1111 is configured to diffract light incident on the optical combiner 110. The holographic grating 1111 of the optical combiner 110 can be a reflective holographic grating or a transmissive holographic grating. The holographic grating 1111 is a volume holographic grating. It is worth noting that the light diffracted by the volume holographic grating can propagate based on Bragg's law.

[0046] Please refer to Figure 8. Figure 8 is a partial schematic diagram illustrating an optical combiner 110' according to another embodiment of the present disclosure. As shown in Figure 8, in this embodiment, the light-transmitting substrate 111' of the optical combiner 110' includes a plurality of surface structures 1111'. The optical combiner 110' utilizes the surface structures 1111' to form a width-periodic structure. The surface structures 1111' can be manufactured to form a surface relief diffraction grating, and the surface relief diffraction grating can form a holographic grating. Thus, the diffraction characteristics of the holographic grating of the optical combiner 110' formed by the surface relief diffraction grating can be the same as or similar to the diffraction characteristics of the holographic grating of the optical combiner 110 formed by the volume holographic grating.

[0047] Please refer to Figure 9. Figure 9 is a partial schematic diagram illustrating an optical combiner 110'' according to another embodiment of this disclosure. As shown in Figure 9, in this embodiment, the optical combiner 110'' includes a plurality of liquid crystal molecules 111'' disposed between two photoalignment layers 112a, 112b, and the photoalignment layers 112a, 112b are sandwiched between two light-transmitting substrates 113a, 113b. A voltage can be applied to the photoalignment layers 112a, 112b to rotate the liquid crystal molecules 111'', thereby forming a width-periodic structure. In other words, the optical combiner 110'' utilizes the internal liquid crystal molecules 111'' to form a width-periodic structure, therefore the outer surfaces of the light-transmitting substrates 113a, 113b have no solid structure. The rotating liquid crystal molecules 111'' can form a liquid crystal grating, and the liquid crystal grating can form a holographic grating. Thus, the diffraction characteristics of the holographic grating of the optical combiner 110'' formed by the liquid crystal grating can be the same as or similar to the diffraction characteristics of the holographic grating of the optical combiner 110 formed by the volume holographic grating.

[0048] In some embodiments, at least one of the optical combiner 110 and the optical combiner 210 may be a waveguide element, a reflective lens element, a semi-transparent lens element and a freeform lens element, but this disclosure is not limited thereto.

[0049] From the detailed description of the specific embodiments disclosed above, it is clear that in the optical assemblies and optical devices disclosed herein, a series of phosphors configured to emit visible light when excited by invisible light are disposed on or distributed within the light-transmitting substrate of the optical assemblies. By emitting visible light when excited by invisible light, the color of the light perceived by the user can be adjusted and enhanced, thereby achieving color balance and improving the visual quality of the augmented reality experience. By employing one or more series of phosphors that respond to different invisible light emitting elements, various color adjustments and effects can be achieved, and even dynamic color control may be possible. In other words, the present disclosure employs an optical assemblies containing phosphors, which, using an additive color mixing method, can effectively manage the color of virtual images superimposed on real-world scenes after being excited by invisible light. Therefore, this disclosure effectively solves the problems encountered in traditional optical devices, such as color distortion of virtual images and the difficulty in achieving the required color balance. These traditional optical devices rely solely on adjusting the light-emitting elements of virtual images or are significantly affected by ambient light, thereby improving the color fidelity and overall immersion of users in augmented reality experiences. In addition, using invisible light to excite phosphors can minimize the visibility of the light-emitting elements themselves and prevent unnecessary visual interference.

[0050] Although this disclosure has been described in considerable detail with reference to certain embodiments thereof, other embodiments are also possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments included in this disclosure.

[0051] It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of this disclosure without departing from the scope or spirit of this disclosure. In view of the foregoing, this disclosure is intended to cover modifications and variations thereof, provided they fall within the scope of the following claims. [Simplified Explanation of the Diagram]

[0024] To make the above and other objects, features, advantages and embodiments of this disclosure more apparent and understandable, the accompanying drawings are described below: Figure 1 is a schematic diagram illustrating an optical device according to one embodiment of this disclosure. Figure 2 is a schematic diagram illustrating the optical combiner in Figure 1. Figure 3 is a schematic diagram illustrating additive color mixing. Figure 4 is a schematic diagram illustrating an optical device according to another embodiment of this disclosure. Figure 5 is a schematic diagram illustrating an optical device according to another embodiment of this disclosure. Figure 6 is a functional block diagram illustrating the optical device in Figure 5. Figure 7 is a partial schematic diagram illustrating the optical combiner in Figure 2. Figure 8 is a partial schematic diagram illustrating an optical combiner according to another embodiment of this disclosure. Figure 9 is a partial schematic diagram illustrating an optical combiner according to another embodiment of this disclosure. [Biomaterial Storage]

[0053] Domestic storage information (please note in order of storage institution, date, and number): None. International storage information (please note in order of storage country, institution, date, and number): None.

Claims

1. An optical combiner comprising: a light-transmitting substrate; a series of phosphors disposed on the light-transmitting substrate and configured to emit visible light when excited by an invisible light; and another series of phosphors disposed on the light-transmitting substrate and configured to emit another visible light when excited by another invisible light.

2. The optical assemblies as claimed in claim 1, wherein the series of phosphors are distributed within the light-transmitting substrate.

3. The optical assemblies as claimed in claim 1, wherein the series of phosphors are disposed on one edge of the light-transmitting substrate.

4. The optical combiner as claimed in claim 1, wherein the invisible light is infrared light.

5. The optical combiner as claimed in claim 4, wherein the infrared light has a wavelength of approximately 940 nm.

6. The optical combination as claimed in claim 1, wherein the light-transmitting substrate is a diffraction structure or a reflection structure.

7. An optical device comprising: a light-emitting element configured to emit an invisible light; another light-emitting element configured to emit a different invisible light; and an optical combiner disposed in an optical path of the invisible light and an optical path of the different invisible light, wherein the optical combiner comprises a series of phosphors and another series of phosphors, the series of phosphors being configured to emit visible light when excited by the invisible light, and the other series of phosphors being configured to emit another visible light when excited by the different invisible light.

8. The optical device as claimed in claim 7, wherein the optical assembly further includes a light-transmitting substrate, and the series of phosphors are distributed within the light-transmitting substrate.

9. The optical device as claimed in claim 7, wherein the optical assembly further includes a light-transmitting substrate, and the series of phosphors are disposed on an edge of the light-transmitting substrate.

10. The optical device as claimed in claim 7, wherein the invisible light is infrared light.

11. The optical device as claimed in claim 10, wherein the infrared light has a wavelength of about 940 nm.

12. The optical device as claimed in claim 7, wherein the optical assembly further includes a light-transmitting substrate, and the light-transmitting substrate is a diffraction structure or a reflection structure.

13. The optical device as claimed in claim 7 further includes a controller configured to individually control the light-emitting element and the other light-emitting element.

14. An optical device comprising: a light-emitting element configured to emit invisible light; an optical combiner disposed in an optical path of the invisible light, wherein the optical combiner includes a series of phosphors configured to emit visible light when excited by the invisible light; a color sensor configured to generate a sensing signal in response to sensing ambient light; and a controller configured to control the light-emitting element according to the sensing signal.

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