System for observing an object by using a holographic optical element

Abstract

A system for observing an object by using a holographic optical element is provided. The system for observing an object includes an infrared (IR) light source that emits IR light, a holographic optical element (HOE) including an optical element film that reflects and diffracts a specific wavelength of the IR light emitted from the IR light source toward the object, and an IR light detector that detects the specific wavelength of the IR light reflected from the object.

Description

Technical Field

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2020-0135094, filed with the Korean Intellectual Property Office on October 19, 2020, and Korean Patent Application No. 10-2021-0139197, filed with the Korean Intellectual Property Office on October 19, 2021, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to a system for observing an object using a hologram optical element (HOE), and more particularly, to a system for observing an object using a hologram optical element that reflects light of a specific wavelength in infrared light. Background Technology

[0004] In recent years, infrared (IR) light sources and sensors have been used to check whether someone is in the driver's seat of a vehicle. IR light sources can directly illuminate the driver, and sensors can then detect the light reflected or scattered from the driver to determine whether the driver is in the vehicle.

[0005] Here, the IR light source can primarily use light-emitting diodes (LEDs) with wavelengths including approximately 850 nm. However, LEDs have a broad wavelength spectrum, so the driver can see red light, which may obstruct the driver's vision while driving. This problem can be solved by reflecting only specific wavelengths of light and transmitting that light indirectly to the driver, rather than by transmitting the IR light source directly to the driver.

[0006] Therefore, it is necessary to develop a system for observing objects without obstructing the driver's view by using holographic optical elements, which include an optical element film that transmits some wavelengths of light from an IR light source and reflects other wavelengths of light.

[0007] The information disclosed in this background section is only intended to enhance the understanding of the background technology of the present invention, and therefore may contain information that does not constitute prior art known to a person skilled in the art in this country. Summary of the Invention

[0008] Technical issues

[0009] An exemplary embodiment of the present invention provides a system for observing an object using holographic optical elements, which reflects only light of a specific wavelength from an infrared (IR) light source without obstructing the driver's view.

[0010] Technical solution

[0011] According to an exemplary embodiment of the present invention, a system for observing an object includes: an infrared (IR) light source that emits infrared light; a holographic optical element (HOE) including an optical element film that causes infrared light of a specific wavelength emitted from the IR light source to be reflected and diffracted toward the object; and an IR photodetector that detects the infrared light of the specific wavelength reflected from the object.

[0012] The optical element film may include a base layer, a HOE recording layer stacked on one surface of the base layer that reflects and diffracts infrared light of a specific wavelength in the infrared light incident through the base layer, and a protective layer stacked on one surface of the HOE recording layer that protects the HOE recording layer.

[0013] Optical element films can reflect infrared light of specific wavelengths in the range of 660nm to 1510nm.

[0014] The optical element film can preferably reflect infrared light of a specific wavelength in the range of 845nm to 855nm or 935nm to 945nm.

[0015] The diffraction angle of the optical element film can be set in the range of 20° or greater, 30° or greater, or 40° or greater, 85° or less, 80° or less, or 75° or less, or in the range of 20° to 85°. Preferably, the diffraction angle of the optical element film is set in the range of 30° to 85°. More preferably, the diffraction angle of the optical element film is set in the range of 40° to 85°.

[0016] The diffraction efficiency of an optical element film can be expressed as the ratio of the intensity (D) of infrared light diffracted from the optical element film to the intensity (I) of infrared light incident on the optical element film, and is set to 30% or greater.

[0017] The diffraction efficiency of the optical element film can preferably be set to 60% or greater, 70% or greater, 75% or greater, or 80% or greater.

[0018] An IR light source can be configured to allow infrared light to be incident on a holographic optical element at an incident angle of -15° to +15°.

[0019] The object can be positioned within the diffraction angle range of the optical element film, and the IR photodetector can be configured to face the object to detect infrared light of a specific wavelength reflected from the object.

[0020] Beneficial effects

[0021] According to an exemplary embodiment of the present invention, the driver's vision can be prevented from being obstructed by reflecting only a specific wavelength of light incident from the IR light source toward the driver.

[0022] In the detailed description of one embodiment of the invention, additional effects that can be obtained or predicted by one embodiment of the invention are disclosed, directly or implicitly. That is, various effects predicted based on one embodiment of the device are disclosed in the detailed description below. Attached Figure Description

[0023] Figure 1 This is a diagram schematically illustrating a system for observing an object using holographic optical elements according to an exemplary embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram illustrating a stacked structure of optical element films included in a holographic optical element according to an exemplary embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram illustrating the transmission and diffraction of light after it has been incident on an optical element film according to an exemplary embodiment of the present invention.

[0026] Figure 4 The figure shown is an experimental result obtained by using a spectrometer to obtain the transmittance and diffraction efficiency of an optical element film according to an exemplary embodiment of the present invention. Detailed Implementation

[0027] In the following description, exemplary embodiments of the invention will be described in detail with reference to the accompanying drawings, enabling those skilled in the art to readily implement the invention. The invention will be described more fully below with reference to the accompanying drawings, in which exemplary embodiments of the invention are illustrated. The invention can be modified in various different forms and is not limited to the embodiments provided in this specification.

[0028] Furthermore, in several exemplary embodiments, components with the same configuration will be described representatively using the same reference numerals in one exemplary embodiment, while in other exemplary embodiments only components that differ from those in one exemplary embodiment will be described.

[0029] It should be understood that the accompanying drawings are schematic and not drawn to scale. To ensure clarity and ease of interpretation, the dimensions and scales of components in the drawings are shown as relatively enlarged or reduced. These arbitrary dimensions are illustrative only and not limiting. Furthermore, the same reference numerals are used to indicate similar features of the same structures, elements, or parts shown in two or more drawings. When an element is described as being "on" or "above" another element, it should be understood that the element may be directly "on" or "above" the other element, with other elements included in between.

[0030] An exemplary embodiment of the present invention can be specifically described. Therefore, various modifications can be made to the figures. Thus, the exemplary embodiment is not limited to the specific shape of the shown portion, but may include shapes modified, for example, during production.

[0031] The following describes in detail, with reference to the accompanying drawings, a system for observing an object using a holographic optical element (HOE) according to an exemplary embodiment of the present invention.

[0032] Figure 1 This is a diagram schematically illustrating a system for observing an object using holographic optical elements according to an exemplary embodiment of the present invention; and Figure 2 This is a schematic diagram illustrating a stacked structure of optical element films included in a holographic optical element according to an exemplary embodiment of the present invention.

[0033] Reference Figure 1 A system 100 for observing an object using holographic optical elements, according to an exemplary embodiment of the present invention, may include an infrared (IR) light source 10, a holographic optical element 30, and an IR photodetector 40.

[0034] The IR light source 10 can be disposed on the side of the vehicle body 1 to emit infrared light toward the holographic optical element 30. Furthermore, the holographic optical element 30 can be disposed below a window on the front side of the vehicle body 1. The IR light source 10 can be mounted to emit infrared light from the side of the vehicle body 1 toward the holographic optical element 30 disposed on the front side inside the vehicle body 1. In an exemplary embodiment, the IR light source 10 can be configured to allow infrared light to incident on the holographic optical element 30 at an incident angle of approximately -15° to approximately +15°.

[0035] The holographic optical element 30 may include an optical element film 20, which can reflect infrared light of a specific wavelength incident from the IR light source 10. Here, the specific wavelength of the infrared light reflected from the optical element film 20 may be in the range of about 660 nm to about 1510 nm, and may preferably be in the range of about 845 nm to about 855 nm or about 935 nm to about 945 nm.

[0036] The IR light detector 40 can detect infrared light of a specific wavelength reflected from the holographic optical element 30. The IR light detector 40 can be positioned above the front window of the vehicle body 1. Infrared light emitted from the IR light source 10 can be incident on the optical element film 20 of the holographic optical element 30, and infrared light of a specific wavelength reflected from the optical element film 20 can be incident towards the object (or driver) 2. Furthermore, infrared light of a specific wavelength reflected from the object 2 can be detected by the IR light detector 40 to determine the presence of the object 2 in the vehicle. The IR light detector 40 can be an IR camera.

[0037] Figure 2 This is a schematic diagram illustrating a stacked structure of optical element films included in a holographic optical element according to an exemplary embodiment of the present invention.

[0038] Reference Figure 2 The optical element film 20 may include a base layer 22, a HOE recording layer 23, and a protective layer 25. The base layer 22 may be made of an optically transparent polymer material and may be an optical adhesive layer of optically clear adhesive (OCA). The base layer 22 may be disposed on one surface of an optical plate 21. The optical plate 21 is not limited to this and may be an optical lens or an optical waveguide. Infrared light emitted from the IR light source 10 can pass through the optical plate 21 and incident on the base layer 22, and then be transmitted to the HOE recording layer 23.

[0039] The HOE recording layer 23 can be stacked on a surface of the base layer 22 and can reflect infrared light of a specific wavelength. The wavelength of the infrared light reflected from the HOE recording layer 23 can be in the range of about 660 nm to about 1510 nm, and can be in the range of about 845 nm to about 855 nm or about 935 nm to about 945 nm.

[0040] The thickness of the HOE recording layer 23 can be from about 3 μm to about 50 μm, preferably from about 8 μm to about 15 μm.

[0041] The protective layer 25 can be stacked on one surface of the HOE recording layer 23, and can be a single layer or multiple layers that have anti-reflective, moisture-proof, or both functions to protect the HOE recording layer 23. The protective layer 25 can be made of an optically transparent polymer material and can be an anti-reflective film.

[0042] Figure 3 This is a schematic diagram illustrating the transmission and diffraction of light after it has been incident on an optical element film according to an exemplary embodiment of the invention; and Figure 4The figure shown is an experimental result obtained by using a spectrometer to obtain the transmittance and diffraction efficiency of an optical element film according to an exemplary embodiment of the present invention.

[0043] Reference Figure 3 A portion of the infrared light (I) incident on the optical element film 20 can be transmitted (T), and a portion of it can be diffracted (D). A portion of the light (I) incident from the HOE recording layer 23 can be diffracted, and the diffraction angle (θ) can be set in the range of 20° or greater, 30° or greater, or 40° or greater, 85° or less, 80° or less, or 75° or less, or in the range of 20° to 85°. The diffraction angle (θ) of the optical element film can preferably be set in the range of 30° to 85°. The diffraction angle (θ) of the optical element film can more preferably be set in the range of 40° to 85°. The object 2 can be positioned within the range of the diffraction angle (θ).

[0044] Furthermore, the incident angle of light (I) incident on the optical element film 20 can be in the range of approximately -15° to approximately +15°. Here, the incident angle of light (I) incident on the optical element film 20 can refer to the angle between the normal to the surface of the optical element film 20 into which light (I) is incident and the incident light (I).

[0045] In addition, refer to Figure 4 It can be seen that the transmittance is low when the wavelength of the light incident on the optical element film 20 is about 850 nm, and the wavelength range of the light reflected from the optical element film 20 is from about 845 nm to about 855 nm. Infrared light with a wavelength range of about 845 nm to about 855 nm can be the main wavelength for observing objects without obstructing the driver's field of vision.

[0046] Within this wavelength range, the diffraction efficiency (dE) of the optical element film 20 can be expressed as the ratio of the intensity (D) of the infrared light diffracted from the optical element film 20 to the intensity (I) of the infrared light incident on the optical element film 20.

[0047] Reference Figure 4 It can be determined that when the intensity (I) of the infrared light incident on the optical element film 20 is 100%, the transmittance in the wavelength range of approximately 850 nm is approximately 35%. Therefore, this indicates that the diffraction efficiency (dE) of the optical element film 20 is approximately 65%. In one exemplary embodiment, for an object 2 to be detected by the IR photodetector 40, the diffraction efficiency of the optical element film 20 can be set to approximately 30% or greater. The diffraction efficiency of the optical element film 20 can preferably be set to approximately 60% or greater. More preferably, the diffraction efficiency of the optical element film 20 can be set to approximately 60% or greater, 70% or greater, 75% or greater, or 80% or greater.

[0048] As described above, according to an exemplary embodiment of the present invention, a system for observing an object using holographic optical elements can prevent the driver's field of vision from being obstructed by reflecting only light of a specific wavelength incident from an IR light source toward the driver.

[0049] While the invention has been described in conjunction with embodiments now considered practical and exemplary, it should be understood that the invention is not limited to the disclosed embodiments. Rather, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1.A system of observing a driver in a vehicle, the system comprising: an infrared light source that emits infrared light; a holographic optical element including an optical element film that reflects and diffracts the emitted infrared light, wherein only infrared light of a specific wavelength among the emitted infrared light is reflected toward the driver; and an infrared light detector that detects the infrared light of the specific wavelength reflected from the driver, wherein the optical element film reflects infrared light of the specific wavelength in a range of 660 nm to 1510 nm. 2.The system according to claim 1, wherein the optical element film includes: a base layer, a holographic optical element recording layer stacked on one surface of the base layer and reflecting and diffracting the infrared light of the specific wavelength among infrared light incident through the base layer, and a protective layer stacked on one surface of the holographic optical element recording layer and protecting the holographic optical element recording layer. 3.The system according to claim 1, wherein the optical element film reflects infrared light of the specific wavelength in a range of 845 nm to 855 nm or 935 nm to 945 nm. 4.The system according to claim 2, wherein a diffraction angle of the optical element film is set in a range of 40° to 85°. 5.The system according to claim 2, wherein a diffraction efficiency of the optical element film, which is expressed as a ratio of intensity of infrared light diffracted from the optical element film to intensity of infrared light incident on the optical element film, is set to 30% or more. 6.The system according to claim 5, wherein the diffraction efficiency of the optical element film is set to 60% or more. 7.The system according to claim 1, wherein the infrared light source is disposed to allow infrared light to be incident on the holographic optical element at an incident angle of -15° to +15°. 8.The system according to claim 4, wherein the driver is positioned within a range of the diffraction angle of the optical element film, and the infrared light detector is disposed to face the driver to detect the infrared light of the specific wavelength reflected from the driver.

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