TWI869667B - Ultra-wide-angle infrared filter lens for day and night use - Google Patents

Abstract

An ultra-wide-angle infrared filter lens for day and night use, the outer surface of which is provided with a thin film structure composed of a plurality of asymmetric film stacks. The film stack is composed of high-refractive-index materials and low-refractive-index materials with different refractive indices, so that when light enters each layer of different refractive index films in the asymmetric film stack, different phase differences are generated, and at the same time, S polarized light and P polarized light are further optimized and adjusted for the film thickness under different phase differences, and the polarized light with an incident angle of 30 degrees is redesigned through the film to correct the optical path thickness to the same structure as the polarized light with an incident angle of 0 degrees. As a result, the incident angle of 30 degrees and the incident angle of 0 degrees can obtain a similar spectrum to achieve the effect of high infrared light transmittance, such that the filter lens can be used during the day and night.

Description

Ultra-wide-angle infrared filter for day and night use

The present invention relates to a filter lens, and in particular to a dual-purpose ultra-high wide-angle infrared filter lens that can be used both day and night.

As we all know, nighttime image observation was first done with thermal imaging infrared instruments. This is based on the basic principle that all objects above absolute 0 degrees radiate infrared rays. The instrument detects and identifies the target by the difference between the infrared radiation of the target and the background. The infrared radiation intensity of each object is different, so different objects can be clearly distinguished.

Later, some people used instruments to emit infrared beams to illuminate the target and convert the infrared image reflected by the target into a visible light image to perform night observation. Then, some people used image sensor components to achieve this.

An image sensor is a device that converts light signals into analog signals. The output analog signals are transmitted to the image processor for analog/digital conversion and color adjustment, and then become digital image information. It is one of the components of digital cameras and network surveillance cameras. Its function is similar to the film of traditional cameras. It is divided into two types: CCD (charge coupled device) and CMOS (complementary metal oxide semiconductor). It is distinguished by resolution and sensitivity. When the shutter is opened, the image light shines on the surface of the CCD element. Using the photoelectric effect, the element generates charge as a basis for judging the intensity of light. In response to the sensitivity requirements of related image sensors, especially those using infrared (ingrared) @850nm band (infrared wavelength is between @760nm~@1mm, corresponding to frequency between @430THz~@300GHz) at night with high transmittance, this infrared application @850nm band has become a future demand for optical components in the current market; that is, if the incident light angle of optical components in the @850nm band is 0~30 degrees, it must also meet high transmittance to meet the requirements.

The light transmittance (T%) of the current image sensor produced by the optical component factory will be affected by the displacement of the light penetration angle. As shown in Figure 1, the current optical components can generally obtain high light transmittance (nearly 98%~99%) when the incident light angle is 0 or 30 degrees in the daytime lighting environment (light wavelength is @700nm or less). However, in the night environment (light wavelength is @850nm), the light transmittance is significantly different when the incident light angle is 0 and 30 degrees. In particular, when the incident light angle is 30 degrees, the infrared light transmittance is too low and cannot meet the actual requirements.

In addition, please refer to Figure 2. When a beam of light waves is irradiated on a thin film, due to the different refractive indices of light, the light waves will be reflected by the upper and lower interfaces of the thin film respectively, and new light waves will be formed due to mutual interference. This is called thin film interference, which can reveal information about the surface of the thin film, including its thickness and refractive index. Therefore, it can be used in mirrors, lenses, filters, etc. According to the principle of thin film interference, light generates two polarized lights, S-pol (S-polarized light) and P-pol (P-polarized light), when the incident angle changes from 0 to 30 degrees. Each wave is transmitted on a plane formed by the wave direction and vibration direction. The present invention is based on the above optical angle characteristics and utilizes two different refractive index materials, high refractive index material: Ti ₃ O ₅ (titanium pentoxide) and low refractive index material: SiO ₂ (silicon dioxide) to obtain the base film stack filter film of the thin film optical design of the present invention, which is then applied to the lens.

In view of the above shortcomings of conventional filters, the inventor has been tirelessly conducting research and improvement. After many tests and improvements, the ultra-high wide-angle infrared filter of this invention is finally produced for both day and night use.

Therefore, the present invention aims to provide an ultra-high wide-angle infrared filter for both day and night use, which uses a multi-layer thin film stack so that the polarized light of light with an incident angle of 30 degrees is corrected by the thin film to achieve the same structure as the polarized light with an incident angle of 0 degrees, thereby improving the transmittance of infrared light with an incident angle of 30 degrees when used at night.

According to the day and night ultra-wide-angle infrared filter of the present invention, it can make the infrared light with a wavelength of @850nm have the same penetration rate as that at 0 degrees when incident at 30 degrees. In this way, the filter has a filtering effect at both day and night when the incident angle is 0 degrees or 30 degrees. This is the second purpose of the present invention.

Since the ultra-high wide-angle infrared filter for both day and night use of the present invention has a high transmittance effect for both general visible light during the day and infrared light at night, the image obtained by the filter can be clear and not blurred both during the day and at night, thus enhancing the practicality of the optical device, which is another purpose of the present invention.

As for the ultra-high wide-angle infrared filter lens for day and night use of the present invention, its detailed structure, specific implementation examples and other functions can be fully understood by referring to the following descriptions of the attached figures.

1, 2, 3..., n...: Thin film stack coated on glass substrate GL

L: Light

100:Ultra-wide-angle lens

200: Focus module

210: Optical lenses

220: Infrared filter

230: Sensor cover glass

The first picture is the light pattern diagram of the sensor component of Xijian Optical Component Factory.

Figure 2 is a light pattern diagram of the ultra-wide-angle infrared filter for day and night use of the present invention.

Figure 3 is an illustration of light waves and two polarized lights.

Figure 4 is a diagram showing the changes of the light wave and the two polarized lights at different angles.

Figure 5 is a schematic diagram showing the spectrum changes before and after the light wave enters the thin film stack of the day and night ultra-high wide-angle infrared filter of the present invention.

Figure 6 is a schematic diagram of the lens assembly structure of the ultra-wide-angle infrared filter lens for day and night use of the present invention for use in optical devices such as mobile phones, cameras, laptops, etc.

Figure 7 shows the lens of the ultra-wide-angle infrared filter lens for both day and night use and the image it captures.

As shown in Figure 2, the present invention is based on the principle of thin film interference. The characteristics of two polarized lights, S-pol (S-polarized light) and P-pol (P-polarized light), are generated when the incident angle of light changes from 0 to 30 degrees. Different refractive index materials are used: high refractive index materials, Ti3O5 (titanium trioxide)... and low refractive index materials, SiO2 (silicon dioxide)... to make a thin film optical film stack structure, so as to eliminate the polarization phase difference of the incident light, so that the infrared radiation of the object itself can have a high penetration rate on the filter lens at night, achieving the effect of night photography.

The ultra-high wide-angle infrared filter for day and night use of the present invention is shown in FIG. 3. Its thin film design stack structure is aimed at the different phase differences generated when light enters the different refractive index thin films in the asymmetric film stack. It is mainly for further optimizing the film thickness of the two polarized lights S-pol (S-polarized light) and P-pol (P-polarized light) under different phase differences, and making the spectral changes of the two polarized lights S-pol (S-polarized light) and P-pol (P-polarized light) caused by the oblique incident 30-degree light wave. In the module stack structure, the dark color is a high refractive index material, and the light color is a low refractive index material. Through the optical path thickness of the film, the polarized light incident at an angle of 30 degrees is corrected to the same structure as the polarized light incident at an angle of 0 degrees, so as to obtain a similar spectrum and achieve the effect of high infrared light penetration.

After extremely complicated and lengthy tests, it was found that the film stack structure of the infrared filter of the present invention for day and night use ultra-high wide-angle is as follows: GLASS/L(a ₁ HLHLa ₂ H)^S ₁ LHL(b ₁ HLb ₂ H)^S ₂ LHL(c ₁ HLc ₂ H)^S ₃ L/AIR, where the symbol "^" means multiple; the central wavelength λ =850nm; the optical thickness of the film is 1/4 λ , and the symbol annotations are as follows: a ₁ /a ₂ is a multiple of 0.1~0.3; b ₁ /b ₂ is a multiple of 0.08~0.28; c ₁ /c ₂ is a multiple of 0.1~0.3; S ₁ , S ₂ , S ₃ is an integer power of 4 to 9; H is a high refractive index material; L is a low refractive index material; H is a high refractive index material and can be one of TiO ₂ /Ti ₂ O ₃ /Ti ₃ O ₅ or more; L is a low refractive index material and can be one of SiO ₂ /MgF ₂ or more.

The thin film structure of the present invention generates different phase differences when light enters the different refractive index thin films in the asymmetric film stack. It is mainly for optimizing the film thickness under different phase differences of the two polarized lights, S-pol (S-polarized light) and P-pol (P-polarized light).

Please refer to Figure 4. This is because when light moves forward, it is accompanied by the electric field and magnetic field directions, and always maintains a fixed plane. This light wave is called polarized light. The polarized light in each direction of the spontaneous light source includes two perpendicular directions: the polarized light of the transverse electric field (TE) is called S-polarized light (S-Pol), and the polarized light of the transverse magnetic field (TM) is called P-polarized light (P-Pol). When light enters each layer in this asymmetric film stack, different refractive index films produce different phase differences, which can be used to further optimize the film thickness of the two polarized lights S-pol (S-polarized light) and P-pol (P-polarized light) at different phase differences.

As shown in FIG. 5 , the filter lens of the present invention has a structure of thin film stacks 1, 2, 3..., n... and the last layer N coated on the glass substrate GL. The structure is aimed at the different phase differences generated when light enters the different refractive index thin films in the asymmetric film stack. It is mainly for further optimizing the film thickness of the original S-pol (S-polarized light) and P-pol (P-polarized light) polarized light of the light wave LW that has not yet entered the glass substrate GL at different phase differences. In the film stack structure, the dark color is a high refractive index material, and the light color is a low refractive index material, and the oblique incident 30-degree light wave causes the spectrum of S and P polarized light (turning) to change, that is, the polarized light with an incident angle of 30 degrees is corrected through the optical path thickness of the film to the same structure as the polarized light with an incident angle of 0 degrees, resulting in a similar spectrum, achieving the effect of high infrared light transmittance. This is the functional feature of the present invention.

The ultra-wide-angle infrared filter of the present invention is used as shown in Figure 6, which shows the lens assembly structure of optical devices such as mobile phones, cameras, laptops, etc. The light L enters from the ultra-wide-angle lens 100, passes through the optical lens 210 of the focusing module 200, and the infrared filter 220 of the present invention, causing the sensor cover glass 230 to react. After the filter of the present invention acts, the image obtained at night can be clear as shown in Figure 7.

With the above structure, the resolution and sensitivity can be distinguished directly without the need for additional power. When the shutter is opened, the image light is irradiated on the surface of the CCD element, and the element generates charge by using the photoelectric effect, which serves as the basis for judging the intensity of the light.

In summary, the ultra-high wide-angle infrared filter for day and night use of the present invention has not been seen in any publications, and there are no similar products on the market, so there is no doubt that it is novel. In addition, the unique features and functions of the present invention are far beyond the comparison of common use, so it is indeed more advanced than common use, and meets the provisions of the application requirements of invention patents under the Patent Law of our country, so a patent application is filed in accordance with the law.

However, the above is only a preferred embodiment of the present invention, and it cannot be used to limit the scope of implementation of the present invention. In other words, all simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the content of the specification should still fall within the scope of the patent of the present invention.

L: Light

100:Ultra-wide-angle lens

200: Focus module

210: Optical lenses

220: Infrared filter

230: Sensor cover glass

Claims (5)

A day and night ultra-high wide-angle infrared filter lens is provided with a thin film structure composed of a plurality of asymmetric film stacks on its outer surface. The film stack is formed by stacking high-refractive index materials and low-refractive index materials with different refractive indices, so that when light enters the different refractive index films in the asymmetric film stack, different phase differences are generated. At the same time, the film thickness of S polarized light and P polarized light is further optimized and adjusted under different phase differences. The polarized light with an incident angle of 30 degrees is redesigned through the film to have the same optical path thickness as the polarized light with an incident angle of 0 degrees, so that the incident angle of 30 degrees and the incident angle of 0 degrees can obtain similar spectra, achieving the effect of high infrared light transmittance. The filter lens can be used both during the day and at night. The thin film stack structure is as follows: GLASS/L(a ₁ HLHLa ₂ H)^S ₁ LHL(b ₁ HLHLb ₂ H)^S ₂ LHL(c ₁ HLHLc ₂ H)^S ₃ L/AIR, where the symbol "^" means the multiple; the central wavelength λ=850nm; the optical thickness of the film is 1/4λ, and the symbol annotations are as follows: a ₁ /a ₂ is a multiple of 0.1~0.3; b ₁ /b ₂ is a multiple of 0.08~0.28; c ₁ /c ₂ is a multiple of 0.1~0.3; S ₁ , S ₂ , S ₃ are integer powers of 4~9 respectively; H is a high refractive index material; L is a low refractive index material; H is a high refractive index material and can be one of the following: TiO ₂ /Ti ₂ O ₃ /Ti ₃ O ₅ ; L is a low refractive index material and can be one of the following: SiO ₂ /MgF ₂ . As described in Item 1 of the patent application scope, the ultra-high wide-angle infrared filter for day and night use, wherein the high refractive index materials of the different film stacks are different compounds. As described in Item 1 of the patent application scope, the ultra-high wide-angle infrared filter for day and night use, wherein the high refractive index materials of the different film stacks are the same compound. As described in Item 1 of the patent application scope, the ultra-high wide-angle infrared filter for day and night use, wherein the low refractive index materials of the different film stacks are different compounds. As described in Item 1 of the patent application scope, the ultra-high wide-angle infrared filter for day and night use, wherein the low refractive index materials of the different film stacks are the same compound.

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