Object observation system using holographic optical elements

Abstract

An object observation system using a holographic optical element is disclosed. The object observation system includes an infrared (IR) light source that emits infrared light, a holographic optical element including an optical element film that reflects and diffracts infrared light of a specific wavelength from the infrared light emitted from the IR light source toward an object, and an IR light sensor that detects the infrared light of the specific wavelength reflected by the object.

Description

[Technical field]

[0001] (Cross-reference to related applications) This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0135094 filed on October 19, 2020 and Korean Patent Application No. 10-2021-0139197 filed on October 19, 2021, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to an object observation system using a hologram optical element (HOE), and more particularly to an object observation system using a hologram optical element that reflects infrared light of a specific wavelength. [Background technology]

[0003] In recent years, infrared (IR) light sources and sensors have been used to check whether or not someone is in the driver's seat of a vehicle. The IR light source is shined directly on the driver, and the sensor detects the light reflected or scattered from the driver to determine whether the driver is present.

[0004] However, IR light sources mainly use LEDs with a wavelength band including a wavelength of about 850 nm, and since LEDs have a wide wavelength spectrum, the driver sees red light, which can cause a problem of obstructing the driver's field of vision while driving. To prevent this, the IR light source can be used to reflect only light of a specific wavelength and indirectly send it to the driver instead of directly to the driver, which can solve the above problem.

[0005] For this reason, there is a demand for the development of an object observation system that does not obstruct the driver's field of vision by utilizing a holographic optical element including an optical element film that transmits some wavelengths of light emitted by an IR light source and reflects the remaining wavelengths.

[0006] The matters described in this Background Art section are prepared to enhance understanding of the background of the invention, and may include matters that are not prior art already known to those having ordinary skill in the art to which the technology pertains. Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, an embodiment of the present invention provides an object observation system using a hologram optical element that reflects only light of a specific wavelength of an IR light source from the hologram optical element so as not to obstruct the driver's field of vision. [Means for solving the problem]

[0008] An object observation system according to one embodiment of the present invention may include an infrared (IR) light source that emits infrared light, a hologram optical element including an optical element film that reflects and diffracts infrared light of a specific wavelength among the infrared light emitted from the IR light source toward an object, and an IR light sensor that detects infrared light of a specific wavelength reflected by the object.

[0009] The optical element film may include a base layer, an HOE recording layer laminated on one side of the base layer and reflecting and diffracting infrared light of a specific wavelength among infrared light incident through the base layer, and a protective layer laminated on one side of the HOE recording layer and protecting the HOE recording layer.

[0010] In one aspect, the optical element film can reflect infrared light of a specific wavelength in the range of 660 nm to 1510 nm.

[0011] Preferably, the optical element film can reflect infrared light of a specific wavelength in the range of 845 nm to 855 nm or 935 nm to 945 nm.

[0012] The diffraction angle of the optical element film can be 20° or more, 30° or more, 40° or more, or 85° or less, 80° or less, or 75° or less, or can be set in the range of 20° to 85°. Preferably, the diffraction angle of the optical element film can be set in the range of 30° to 85°. More preferably, the diffraction angle of the optical element film can be set in the range of 40° to 85°.

[0013] In one aspect, the diffraction efficiency of the optical element film, expressed as the ratio of the intensity of infrared light (D) diffracted from the optical element film to the intensity of infrared light (I) incident on the optical element film, may be set to 30% or more.

[0014] Preferably, the diffraction efficiency of the optical element film may be set to 60% or more, or 70% or more, or 75% or more, or 80% or more.

[0015] The IR light source may be positioned to direct infrared light to be incident on the hologram optical element at an angle of incidence between -15° and +15°.

[0016] The object may be located within a diffraction angle of the optical element film, and the IR light detector may be positioned facing the object to detect infrared light of a particular wavelength reflected from the object. Effect of the Invention

[0017] According to an embodiment of the present invention, only light of a specific wavelength among light incident from an IR light source is reflected toward the driver, thereby making it possible to avoid obstructing the driver's field of vision.

[0018] Other effects that can be obtained or are expected from the embodiments of the present invention are directly or implicitly disclosed in the detailed description of the embodiments of the present invention. In other words, various effects expected from the embodiments of the present invention are disclosed in the detailed description below. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic diagram of an object observation system using a hologram optical element according to an embodiment of the present invention. [Diagram 2] 2 is a schematic diagram illustrating a laminated structure of an optical element film of a hologram optical element according to an embodiment of the present invention. [Diagram 3] 4 is a schematic diagram illustrating light incident on an optical element film, which is then transmitted through the optical element film, and diffracted according to an embodiment of the present invention; [Figure 4] 4 is a graph showing transmittance and diffraction efficiency of an optical element film according to an embodiment of the present invention, which are obtained through an experiment using a spectrometer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention may, however, be embodied in various different forms and should not be construed as being limited to the embodiments set forth herein.

[0021] In addition, in many embodiments, components having the same configuration will be described in one embodiment using the same reference numerals, and in other embodiments, only configurations different from the one embodiment will be described.

[0022] It is noted that the drawings are schematic and are not drawn to scale. Relative sizes and proportions of parts shown in the drawings are shown exaggerated or reduced in size for clarity and convenience in the drawings, and any sizes are merely illustrative and not limiting. And, for identical structures, elements or parts that appear in more than one drawing, the same reference numbers are used to denote similar features. When a part is referred to as being "on" another part, it may be immediately on top of the other part, and there may be other parts in between.

[0023] The embodiment of the present invention specifically illustrates an embodiment of the present invention. As a result, various modifications of the illustrations are expected. Therefore, the embodiment is not limited to the specific form of the illustrated region, and includes modifications of the form due to manufacturing, for example.

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an object observation system using a hologram optical element according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0025] FIG. 1 is a diagram illustrating an object observation system using a hologram optical element according to one embodiment of the present invention, and FIG. 2 is a diagram illustrating a laminate structure of an optical element film of a hologram optical element according to one embodiment of the present invention.

[0026] Referring to FIG. 1, an object observation system 100 using a holographic optical element according to an embodiment of the present invention includes an infrared (IR) light source 10, a holographic optical element 30, and an IR light detector 40.

[0027] The IR light source 10 may be disposed on a side surface inside the vehicle body 1 so as to emit infrared light toward the hologram optical element 30. The hologram optical element 30 may also be disposed under a vehicle window at the front inside the vehicle body 1. The IR light source 10 may be installed so as to emit infrared light from a side surface inside the vehicle body 1 toward the hologram optical element 30 disposed at the front inside the vehicle body 1. In one aspect, the IR light source 10 is the hologram optical element 30 and may be disposed so as to cause infrared light to be incident at an incident angle of about -15° to about +15°.

[0028] The hologram optical element 30 includes an optical element film 20, which reflects infrared light of a specific wavelength incident from the IR light source 10. In this case, 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 preferably in the range of about 845 nm to about 855 nm or about 935 nm to about 945 nm.

[0029] The IR light sensor 40 detects infrared light of a specific wavelength reflected from the hologram optical element 30. The IR light sensor 40 may be disposed above the vehicle window at the front inside of the vehicle body 1. The infrared light emitted from the IR light source 10 is incident on the optical element film 20 of the hologram optical element 30, and the infrared light of the specific wavelength reflected from the optical element film 20 is incident towards the object (driver) 2. In addition, the infrared light of the specific wavelength reflected from the object 2 is detected by the IR light sensor 40, making it possible to determine the presence or absence of the object 2. The IR light sensor 40 may be an IR camera.

[0030] FIG. 2 is a schematic diagram showing a laminated structure of an optical element film of a hologram optical element according to an embodiment of the present invention.

[0031] 2, the optical element film 20 includes a base layer 22, an 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 silicone OCA (optically clear adhesive). The base layer 22 may be disposed on an optical plate 21 (on one side of the optical plate 21). The optical plate 21 may be, but is not limited to, an optical lens or an optical waveguide plate. Infrared light emitted from the IR light source 10 may be incident on the base layer 22 through the optical plate 21 and transmitted to the HOE recording layer 23.

[0032] The HOE recording layer 23 is laminated on the base layer 22 (on one surface of the base layer 22) and can reflect infrared light of a specific wavelength. The wavelength of the infrared light reflected by this HOE recording layer 23 can be in the range of about 660 nm to about 1510 nm, and can also be in the range of about 845 nm to about 855 nm, or about 935 nm to about 945 nm.

[0033] The HOE recording layer 23 can be formed to have a thickness of about 3 μm to about 50 μm, preferably about 8 μm to about 15 μm.

[0034] The protective layer 25 is laminated on the HOE recording layer 23 (on one side of the HOE recording layer 23) and may be in the form of a single layer or multiple layers having an anti-reflection function, a moisture permeation prevention function, or both of these functions to protect the HOE recording layer 23. The protective layer 25 may be formed of an optically transparent polymer material, and may be formed of an anti-reflection film.

[0035] FIG. 3 is a schematic diagram showing light incident on an optical element film according to an embodiment of the present invention and being transmitted and diffracted, and FIG. 4 is a graph showing the transmittance and diffraction efficiency of an optical element film according to an embodiment of the present invention, which are obtained through an experiment using a spectrometer.

[0036] Referring to FIG. 3, a part of infrared light (I) incident on the optical element film 20 is transmitted (T) and a part of it is diffracted (D). A part of the light (I) incident on the HOE recording layer 23 is diffracted, and at this time, the diffraction angle (θ) may be 20° or more, 30° or more, 40° or more, 85° or less, 80° or less, or 75° or less, or may be set in a range of 20° to 85°. Preferably, the diffraction angle (θ) of the optical element film may be set in a range of 30° to 85°. More preferably, the diffraction angle (θ) of the optical element film may be set in a range of 40° to 85°. The object 2 may be located within the range of the diffraction angle (θ).

[0037] In addition, the incident angle of the light (I) incident on the optical element film 20 may be about -15° to about +15°. Here, the incident angle of the light (I) incident on the optical element film 20 means the angle between the normal to the surface of the optical element film 20 on which the light (I) is incident and the incident light (I).

[0038] 4, it can be seen that the transmittance is low when the wavelength of light incident on the optical element film 20 is about 850 nm, which means that the wavelength range reflected from the optical element film 20 is about 845 nm to about 855 nm. Infrared light having a wavelength range of about 845 nm to about 855 nm is the main wavelength used for object observation and does not obstruct the driver's field of vision.

[0039] In this wavelength range, the diffraction efficiency (dE) of the optical element film 20 can be determined from the ratio of the intensity of the infrared light (D) diffracted from the optical element film 20 to the intensity of the infrared light (I) incident on the optical element film 20.

[0040] In FIG. 4, it can be seen that when the intensity (I) of infrared light incident on the optical element film 20 is 100%, the transmittance in the wavelength range of about 850 nm is about 35%. Therefore, the diffraction efficiency (dE) of the optical element film 20 is shown to be about 65%. In one example, the diffraction efficiency of the optical element film 20 may be set to about 30% or more so that the object 2 can be detected by the IR light sensor 40. Preferably, the diffraction efficiency of the optical element film 20 may be set to about 60% or more. More preferably, the diffraction efficiency of the optical element film 20 may be set to about 60% or more, or 70% or more, or 75% or more, or 80% or more.

[0041] Thus, according to an embodiment of the present invention, an object observation system using a holographic optical element can be used to reflect only light of a specific wavelength incident from an IR light source toward the driver, thereby preventing interference with the driver's field of vision.

[0042] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and includes all modifications that can be easily modified from the embodiments of the present invention by a person having ordinary knowledge in the technical field to which the invention belongs and are recognized as equivalent.

Claims

1. an infrared (IR) light source that emits infrared light; a hologram optical element including an optical element film that reflects and diffracts infrared light of a specific wavelength among the infrared light emitted from the IR light source toward an object; and an IR light sensor that detects infrared light of a specific wavelength reflected by the object; Including, The optical element film is Base layer, a HOE recording layer laminated on one surface of the base layer and configured to reflect and diffract infrared light of a specific wavelength among infrared light incident through the base layer; and a protective layer laminated on one surface of the HOE recording layer to protect the HOE recording layer; Including, An object observation system that reflects infrared light of a specific wavelength in the range of 660 nm to 1510 nm, the infrared light of the specific wavelength not interfering with the driver's field of vision.

2. 2. The object observation system according to claim 1, wherein the optical element film reflects infrared light of a specific wavelength in the range of 845 nm to 855 nm or 935 nm to 945 nm.

3. 3. The object observation system according to claim 1, wherein the diffraction angle of the optical element film is set in the range of 40° to 85°.

4. The diffraction efficiency of the optical element film is An object observation system as described in any one of claims 1 to 3, wherein the ratio of the intensity of infrared light (D) diffracted from the optical element film to the intensity of infrared light (I) incident on the optical element film is set to 30% or more.

5. The object observation system according to claim 4 , wherein the diffraction efficiency of the optical element film is set to 60% or more.

6. 6. The object observation system according to claim 1, wherein the IR light source is arranged to make infrared light incident on the hologram optical element at an incident angle of -15° to +15°.

7. the object is located within a range of a diffraction angle of the optical element film; 7. The object observation system according to claim 3, wherein the IR light sensor is disposed facing the object so as to detect infrared light of a specific wavelength reflected from the object.

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