Patent Grant
9851531
Present embodiments relate to an optical lens assembly and an imaging lens, and particularly, relates to an optical lens assembly and an imaging lens with infrared (IR) ray filtering.
Tables 4-6 depicts a summary of values of transmittance in the wavelength range between 850 nm to 1300 nm for an IR filter formed with the 60 layers of IR filtering thin film on the object-side surface and the 4 layers of anti-reflection thin film on the image-side surface:
The transmittance is approximately less than 3% in the range of wavelength between 875 nm to 1250 nm.
The spectrum shown in
As illustrated in
Therefore, the transmittance in the IR light band of one piece of the IR filter formed with 60 layers of IR filtering thin film on the object-side surface and 4 layers of anti-reflection thin film on the image-side surface is approximately less than 3%, and the transmittance for visible light, such as incident light having wavelength between 450 nm to 650 nm, is greater than 80%. With the help of the IR filter formed with the 60 layers of IR filtering thin film on the object-side surface and the 4 layers of anti-reflection thin film on the image-side surface, the transmittance of the optical lens assembly for the IR light band is less than 1.1% and the transmittance for visible light is also very good. However, because the additional IR filter effectively increases the total length of the optical lens assembly, applications of the optical lens assembly in products seeking lighter and thinner appearances are substantially limited.
Present example embodiments provide an optical lens assembly and imaging lens with infrared (IR) light filtering which do not use an additional IR filter, unlike the conventional optical lens assembly, to shorten the total length of the optical lens assembly.
Example embodiments also provide for an optical lens assembly and imaging lens with infrared (IR) light filtering, which reduces the transmittance of the imaging lens for incident light with wavelength between 900 nm to 1250 nm. Filtering is performed on the IR light for wavelengths between 900 nm to 1250 nm through a plurality of optical thin films of the first material and a plurality of optical thin films of the second material layered along a direction and the structure where each of the optical thin films of the second material is layered between two adjacent layers of optical thin films of the first material in the optical thin films.
Example embodiments also provide for an optical lens assembly and imaging lens with infrared (IR) light filter which reduces transmittance of the imaging lens for incident light having wavelength between 900 nm to 1250 nm through controlling the layered number along the direction and thickness of each layer of the optical thin films layered on the surface(s) of the imaging lens.
Example embodiments also provide for an imaging lens comprising: (a) for incident light with wavelength between 500 nm to 1300 nm, minimum transmittance of the imaging lens within a range between 900 nm and 1250 nm; (b1) for incident light with wavelength between 900 nm to 1250 nm, transmittance of the imaging lens is not greater than 60%; and (c) for incident light with wavelength between 450 nm to 650 nm, transmittance of the imaging lens is greater than 80%.
Example embodiments also provide for an optical lens assembly comprising: (a) for incident light with wavelength between 500 nm to 1300 nm, minimum transmittance of the optical lens assembly falls within a range between 900 nm and 1250 nm; (b2) for incident light with wavelength between 900 nm to 1250 nm, transmittance of the optical lens assembly is not greater than 10%; and (c) for incident light with wavelength between 450 nm to 650 nm, transmittance of the optical lens assembly is greater than 80%.
Example embodiments also provide for an imaging lens comprising: a body having a refracting index and comprising two surfaces, at least one of the surfaces having a curved surface portion, and a plurality layers of optical thin film formed on at least one of the surfaces; the optical thin films having a plurality of optical thin films of a first material and a plurality of optical thin films of a second material layered along a direction, each of the optical thin films of the second material layered between two adjacent layers optical thin films of the first material, the optical thin films of the first material having a first refracting index greater than the refracting index of the body, and the optical thin films of the second material having a second refracting index smaller than the refracting index of the body, a total amount of the optical thin films is no more than 20 layers, and a total thickness of the optical thin films is no less than 400 nm and no greater than 2000 nm; the imaging lens operable as follows: (a) for incident light with wavelength between 500 nm to 1300 nm, minimum transmittance of the imaging lens within a range between 900 nm and 1250 nm; (b1) for incident light with wavelength between 900 nm to 1250 nm, transmittance of the imaging lens is not greater than 60%; and (c) for incident light with wavelength between 450 nm to 650 nm, the transmittance of the imaging lens is greater than 80%.
Example embodiments also provide for an optical lens assembly comprising: an imaging lens assembly comprising at least three pieces of the imaging lens facing opposite directions to each other, the imaging lens respectively comprising a body, the body having a refractive index and comprising two surfaces, at least one of the surfaces having a curved surface portion, a plurality of layers of optical thin film formed on at least one surface of each imaging lens, the optical thin films having a plurality of optical thin films of a first material and a plurality of optical thin films of a second material layered along a direction, and each of the optical thin films of the second material layered between two adjacent layers optical thin films of the first material, the optical thin films of the first material having a first refracting index greater than the refracting index of the body, and the optical thin films of the second material having a second refractive index smaller than the refractive index of the body, a total amount of the optical thin films is no more than 20 layers, and a total thickness of the optical thin films is no less than 400 nm and no greater than 2000 nm; the optical lens assembly operable as follows: (a) for incident light with wavelength between 500 nm to 1300 nm, a minimum transmittance of the optical lens assembly falls within a range between 900 nm and 1250 nm; (b2) for incident light with wavelength between 900 nm to 1250 nm, the transmittance of the optical lens assembly is not greater than 10%; and (c) for incident light with wavelength between 450 nm to 650 nm, the transmittance of the optical lens assembly is greater than 80%.
The imaging lens in the specification has thin films formed on both surfaces. The thin films may comprise other types of thin films not described above. The total amount, total thickness of the optical thin films, and the thickness of each layer could be varied to meet variable needs or requirements, for example, due to different wavelength ranges, application requirements, production technical barriers, or other factors. The total amount and the thickness of the optical thin films may be modified to alter the transmittance, spectrum character or other characters. Preferably, the total number of optical thin films on each surface is not less than 6 layers and not more than 16 layers when both of the two surfaces of the body are formed with the optical thin films, or the total number of optical thin films on each surface is not less than 6 layers and not more than 16 layers when only one surface is formed with the optical thin films. In an exemplary embodiment for reducing the ripple portion in the spectrum filtered by the imaging lens, the thinnest layer of the optical thin films of the first material is controllable to be adjacent to the thinnest layer of the optical thin films of the second material in the optical thin films. Additionally, at the image-side surface, similar controlling manner to the thickness may be optionally applied. As such, through experiments, the collected data shows a better spectrum; however, present embodiments are not limited to this.
Further, the optical thin films in example embodiments are a multilayer-thin-film structure comprising the optical thin films of the first material and the optical thin films of the second material layered along a direction. For example, the optical thin films of the first material are not limited to, but could be chosen from, the group of Ti3O5 (refractive index 2.322), Ta2O5 (refractive index 2.18), H4 (refractive index 1.96, a mixture of TiO2 and La2O3), ZrO2 (refractive index 1.95), OS-50 (refractive index 2.294), and Nb2O5 (refractive index 2.34). Furthermore, the optical thin films of the second material are not limited to, but could be chosen, from the group of SiO2 (refractive index 1.455), and MgF2 (refractive index 1.38). Example embodiments may apply the optical thin films and other types of thin films into implementation. For example, on one of the surfaces of at least one imaging lens of the imaging lens assembly, a plurality of layers of optical thin film in a total of not more than 20 layers could be formed, and on the other surface, a plurality of anti-reflection layers, which transmittance is greater than 80% for incident light with wavelength between 450 nm to 650 nm could be formed, and such implementation also filters a certain level of IR light. In this example embodiment, the surface formed with the anti-reflection thin films is not limited to any of the object-side surface and the image-side surface. In an example embodiment, the object-side surface is formed with the optical thin films and the image-side surface is formed with the anti-reflection layers. In another example embodiment, the object-side surface is formed with the anti-reflection thin films and the image-side surface is formed with the optical thin films.
Through the layered structure of the optical thin films on the surfaces of the imaging lens, which collectively filters the IR light band in the spectrum, example embodiments of the optical lens assembly and imaging lens filters the IR light to reduce the undesirable effects of the IR light upon the imaging sensor of the optical lens assembly and upon the image quality.
Exemplary embodiments will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which:
For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features. Persons having ordinary skill in the art will understand other varieties for implementing example embodiments, including those described herein. The drawings are not limited to specific scale and similar reference numbers are used for representing similar elements. As used in the disclosures and the appended claims, the terms “example embodiment,” “exemplary embodiment,” and “present embodiment” do not necessarily refer to one embodiment, although it may, and various example embodiments may be readily combined and interchanged, without departing from the scope or spirit of the present embodiments. Furthermore, the terminology as used herein is for the purpose of describing example embodiments only and is not intended to be a limitation of the embodiments. In this respect, as used herein, the term “in” may include “in” and “on”, and the terms “a”, “an” and “the” may include singular and plural references. Furthermore, as used herein, the term “by” may also mean “from”, depending on the context. Furthermore, as used herein, the term “if” may also mean “when” or “upon”, depending on the context. Furthermore, as used herein, the words “and/or” may refer to and encompass any and all possible combinations of one or more of the associated listed items.
Example embodiments provide for an optical lens assembly and an imaging lens thereof operable to filter IR light. Each imaging lens comprises a body and a plurality of layers of optical thin film. The body has refractive index and comprises two surfaces, at least one of the surfaces having a curved surface portion, and a plurality of layers of optical thin film formed on at least one of the surfaces. The optical thin films have a plurality of optical thin films of a first material and a plurality of optical thin films of a second material layered along a direction, each of the optical thin films of the second material layered between two adjacent layers of optical thin films of the first material. The optical thin films of the first material have a first refractive index greater than the refractive index of the body, and the optical thin films of the second material have a second refractive index smaller than the refractive index of the body. A total number of the optical thin films on each single surface is not greater than 20 layers, and a total thickness of the optical thin films is not less than 400 nm and not greater than 2000 nm. The imaging lens is operable with the following characteristics: (a) for incident light with wavelength between 500 nm to 1300 nm, a minimum transmittance of the imaging lens falls within a range between 900 nm and 1250 nm; (b1) for incident light with wavelength between 900 nm to 1250 nm, the transmittance of the imaging lens is not greater than 60%; and (c) for incident light with wavelength between 450 nm to 650 nm, the transmittance of the imaging lens is greater than 80%.
The optical lens assembly in example embodiments comprises at least three of the aforesaid imaging lenses having good optical characteristics positioned opposite to each other to form an imaging lens device. The imaging lens device is positioned before an image sensor to allow incident light refracting and entering the image sensor to sense an image. It is understood that the changing of the shape could change the focus of the imaging lens, therefore the shapes of the imaging lenses are not limited and each imaging lens may be in a different shape. Preferably, each imaging lens comprises a body, for example, but not limited to, made by a material having refractive index of 1.533. The body has a refractive index and comprises two surfaces, such as an object-side surface and an image-side surface, at least one of the surfaces having a curved surface portion. On at least one surface of each imaging lens, a plurality of layers of optical thin film are formed, for example, the optical thin films on each single surface having a total number of not more than 20 layers and total thickness of not less than 400 nm and not greater than 2000 nm are formed by vacuum coating. The optical thin films have a plurality of optical thin films of a first material and a plurality of optical thin films of a second material layered along a direction, and each of the optical thin films of the second material is layered between two adjacent layers of optical thin film of the first material. The optical thin films of the first material have a first refractive index which is greater than the refractive index of the body, and the optical thin films of the second material have a second refractive index which is lower than the refractive index of the body. Through the layered optical thin films, preferably, the transmittance of the imaging lens for incident light with wavelength between 900 nm to 1250 nm is reduced, and the optical lens assembly is operable with the following characteristics: (a) for incident light with wavelength between 500 nm to 1300 nm, a minimum transmittance of the optical lens assembly falls within a range between 900 nm and 1250 nm; (b2) for incident light with wavelength between 900 nm to 1250 nm, the transmittance of the optical lens assembly is not greater than 10%; and (c) for incident light with wavelength between 450 nm to 650 nm, the transmittance of the optical lens assembly is greater than 80%. Therefore, example embodiments of the imaging lens or the optical lens assembly are operable to block a significant level of IR lights with wavelength in the range between 900 nm to 1250 nm and also provide good transparency for visible light with wavelength in the range between 450 nm to 650 nm.
The total number, total thickness of the optical thin films, and the thickness of each layer could be varied to meet variable needs or requirements, for example, due to different wavelength ranges, application requirements, production technical barriers, or other factors. The total number and the thickness of the optical thin films may be changed to alter the transmittance, spectrum character or other characters. Preferably, the total number of optical thin films on each surface is not less than 6 layers and not more than 16 layers when both of the two surfaces of the body are formed with the optical thin films, or the total number of optical thin films on each surface is not less than 6 layers and not more than 16 layers when only one surface is formed with the optical thin films. In an exemplary embodiment for reducing the ripple in the spectrum filtered by the imaging lens, at least 6 layers of optical thin film may be layered along a direction on the surface(s) and the thinnest layer of the optical thin films of the first material may be controllable to be adjacent to the thinnest layer of the optical thin films of the second material in the optical thin films. Collected data of example embodiments indicate better achievable spectrum.
Further, the optical thin films in example embodiments are a multilayer-thin-film structure comprising optical thin films of a first material and optical thin films of a second material layered along a direction. The optical thin films of the first material could be chosen from, for example, the group of Ti3O5 (refractive index 2.322), Ta2O5 (refractive index 2.18), H4 (refractive index 1.96, a mixture of TiO2 and La2O3), ZrO2 (refractive index 1.95), OS-50 (refractive index 2.294), and Nb2O5 (refractive index 2.34). Furthermore, the optical thin films of the second material could be chosen from, for example, the group of SiO2 (refractive index 1.455), and MgF2 (refractive index 1.38). Example embodiments are operable to apply the optical thin films and other types of thin films into implementation. For example, on one of the surfaces of at least one imaging lens of the imaging lens assembly, a plurality of layers of optical thin film in a total of not more than 20 layers could be formed, and on the other surface, a plurality of anti-reflection layers, which transmittance is greater than 80% for incident light with wavelength between 450 nm to 650 nm, could be formed, and such implementation also filters a certain level of IR light. In this exemplary implementation, the surface formed with the anti-reflection thin films is not limited to any of the object-side surface and the image-side surface. In an example embodiment, the object-side surface is formed with the optical thin films and the image-side surface is formed with the anti-reflection layers. In another example embodiment, the object-side surface is formed with the anti-reflection thin films and the image-side surface is formed with the optical thin films.
Examples and measured spectrums will hereinafter be provided below to assist in understanding the optical characteristics of the optical lens assembly and the imaging lens for example embodiments. A wide-field light source is provided in front of the object-side surface of the optical lens assembly and the imaging lens thereof to provide wide-field incident light, and the spectrums shown here are obtained by detecting and analyzing the spectrum behind the image-side surface of the optical lens assembly and the imaging lens thereof to illustrate optical characteristics of the optical lens assembly and the imaging lens in example embodiments, but they are not limited to this. The spectrum measured with the same optical lens assembly or imaging lens may be altered by the method for detection or analysis, environment, material or other factors. Meanwhile, it is noted that, for showing the optical characteristics of the optical lens assembly and the imaging lens thereof in a more comprehensive way, exemplary embodiments provide the spectrums of the imaging lens formed with thin films on the object-side surface only, on the image-side surface only, and on both of the object-side surface and the image-side surface in order. However, those with only one surface, including either the object-side surface or the image-side surface formed with thin films, are not so called “imaging lens” in this field. Example embodiments are also not limited to these types of lenses. Besides, for comparing the effect of each embodiment, the data of the following embodiments are obtained based on the imaging lens and the optical lens assembly with the same shape, combination, and material, so as to eliminate the varieties among the embodiments as much as possible.
Referring now to
Embodiment I:
It should be noted that the layer nearest to the imaging lens is designated by the “1st layer”, the 2nd nearest layer to the imaging lens is designated by the “2nd layer”, and so on, and other example embodiments designate the layers in the same manner.
As illustrated in the above tables, the thinnest layer of the optical thin films of the first material is adjacent to the thinnest layer of the optical thin films of the second material in the optical thin films in the present embodiment, and the thicknesses of the 1st and 2nd layers of the optical thin film are thinner than other layers of the optical thin films. Through such adjustment for the thickness, the ripple of the spectrum after the imaging lenses or the optical lens assembly may be effectively reduced in the present embodiment.
The below Tables 13-16 illustrate the measured data of the transmittance for incident light with wavelength between 850 nm to 1300 nm, wherein both surfaces of one piece of the imaging lens are formed with 6 layers of the optical thin film:
Embodiment II:
Please refer to Tables 21-23 for the measured data of the transmittance for incident light with wavelength between 850 nm to 1300 nm of one piece of the imaging lens whose surfaces are both formed with 8 layers of the optical thin film:
Embodiment III:
Please refer to Tables 29-30 for the detail thickness of each layer of the optical thin films of the first material and the optical thin films of the second material and the total thickness of the optical thin films on the image-side surface of the imaging lens in the present embodiment:
Please refer to Tables 31-33 for the measured data of the transmittance for incident light with wavelength between 850 nm to 1300 nm of one piece of the imaging lens having both surfaces formed with 12 layers of the optical thin film:
Embodiment IV:
Please refer to Tables 39-40 for the detail thickness of each layer of the optical thin films of the first material and the optical thin films of the second material and the total thickness of the optical thin films on the image-side surface of the first-type imaging lens in the present embodiment:
Please refer to Tables 41-42 for the detail thickness of each layer of the anti-reflection thin films and the total thickness of the anti-reflection thin films on the both surfaces of the second-type imaging lens in the present embodiment:
The comparison among the first-type imaging lenses is as follows.
Please refer to Tables 43-46 for the measured data of transmittance of incident light with wavelength between 850 nm to 1300 nm of one piece of the first-type imaging lens having both surfaces formed with 12 layers of the optical thin film:
For the second-type imaging lens,
From
Further, the optical lens assembly used in the present embodiment comprises the first-type imaging lens formed with 12 layers of optical thin film on the object-side surface and the image-side surface, and/or the second-type imaging lens formed with 6 layers of anti-reflection thin film on the object-side surface and the image-side surface.
Embodiment V:
Please refer to Tables 54-55 for the detail thickness of each layer of the 12-layer optical thin films of the first material and the optical thin films of the second material and the total thickness of the optical thin films on the image-side surface of the first-type imaging lens in the present embodiment:
Please refer to Tables 56-57 for the detail thickness of each layer of the 12 layers of the optical thin film and the total thickness of the optical thin films on the object-side surface of the third-type imaging lens in the present embodiment:
Please refer to Tables 58-59 for the detail thickness of each layer of the 6 layers of the anti-reflection thin film and the total thickness of the anti-reflection thin films on the image-side surface of the third-type imaging lens in the present embodiment:
A summary of the first-type imaging lenses is as follows.
Please refer to Tables 60-62 for the measured data of the transmittance for incident light with wavelength between 850 nm to 1300 nm of one piece of the first-type imaging lens whose surfaces are both formed with 12 layers of the optical thin film:
For the third-type imaging lens,
Therefore, it is clear that one piece of the third-type imaging lens formed with 12 layers of the optical thin film on the object-side surface and 6 layers of the anti-reflection thin film on the image-side surface shows a better IR filtering characteristic.
Further, the optical lens assembly used here comprises an optical lens assembly comprising the first-type imaging lens formed with 12 layers of optical thin film on both object-side and image-side surfaces and/or the third-type imaging lens formed with 12 layers of optical thin film on the object-side surface and 6 layers of anti-reflection thin film on the image-side surface.
Embodiment VI:
Please refer to Tables 71-72 for details of the thickness of each layer of the optical thin films of the first material and the optical thin films of the second material and the total thickness of the optical thin films on the image-side surface of the imaging lens in the present embodiment:
Please refer to Tables 73-75 for measured data of the transmittance of incident light with wavelength between 850 nm to 1300 nm of one piece of the imaging lens having both surfaces formed with 14 layers of the optical thin film:
The below Table 79 summarizes the transmittance values of the above embodiments based on the spectrum of one piece of the imaging lens formed with the optical thin films or anti-reflection thin films on both object-side and image-side surfaces for incident light with wavelength between 850 nm to 1300 nm:
(a) The Imaging Lens:
As seen from above data:
1. The minimum transmittance of one piece of the imaging lens formed with 6 layers of the optical thin film on the object-side and image-side surfaces of Embodiment I is 30.6% and occurs at a wavelength of 1175 nm.
2. The minimum transmittance of one piece of the imaging lens formed with 8 layers of the optical thin film on the object-side and image-side surfaces of Embodiment II is 13.1% and occurs at a wavelength of 1075 nm.
3. The minimum transmittance of one piece of the imaging lens formed with 12 layers of the optical thin film on the object-side and image-side surfaces of Embodiment III is 2.347% and occurs at a wavelength of 1050 nm.
4. The minimum transmittance of one piece of the first-type imaging lens formed with 12 layers of the optical thin film on the object-side and image-side surfaces of Embodiment IV is 2.347% and occurs at a wavelength of 1050 nm; the minimum transmittance of one piece of the second-type imaging lens formed with 6 layers of the anti-reflection thin film on the object-side and image-side surfaces of Embodiment IV is 74.923047% and occurs at a wavelength of 1300 nm.
5. The minimum transmittance of one piece of the first-type imaging lens formed with 12 layers of the optical thin film on the object-side and image-side surfaces of Embodiment V is 2.347% and occurs at a wavelength of 1050 nm; the minimum transmittance of one piece of the third-type imaging lens formed with 12 layers of the optical thin film on the object-side surfaces and 6 layers of the anti-reflection thin film on the image-side surfaces of Embodiment V is 4.485123% and occurs at a wavelength of 1050 nm.
6. The minimum transmittance of one piece of the imaging lens formed with 14 layers of the optical thin film on the object-side and image-side surfaces of Embodiment VI is 0.97% and occurs at a wavelength of 1025 nm.
7. In summary, the minimum transmittance of one piece of the imaging lens formed with the optical thin films of example embodiments falls within the wavelength range between 900 nm to 1250 nm, and for the range between 900 nm to 1250 nm wavelength, the value of the transmittance is not greater than 60%.
The below Table 80 summarizes the transmittance values and spectrums of the optical lens assembly of example embodiments and conventional optical lens assembly for incident light with wavelength between 850 nm to 1300 nm:
(b) The Optical Lens Assembly:
The transmittance of the conventional optical lens assembly, which uses a combination of the IR filter and five pieces of traditional imaging lens, is not greater than 1% for the wavelength range between 900 nm to 1250 nm. However, the optical lens assembly in example embodiments comprising the imaging lens having multiple layers of the optical thin film or anti-reflection thin films also achieves a transmittance not greater than 1% for the wavelength range between 900 nm to 1250 nm. Since the transmittance shown in Embodiment I may be greater than 1% for the wavelength range between 900 nm to 1000 nm, this is acceptable for low-end products, which could use the optical lens assembly to provide transmittance not greater than 10%.
Additionally, from the values shown in Embodiment II to Embodiment VI, between wavelength 900 nm to 950 nm, the transmittance is far below 1%, and even below 0.01%. Therefore, the effect of filtering the IR lights in example embodiments is much better than those in conventional optical lens assembly assemblies.
Based on the data of above table, it is clear that:
1. The minimum transmittance of the optical lens assembly comprising the five pieces of the imaging lens (formed with 6 layers of the optical thin film on the both object-side and image-side surfaces) of Embodiment I is 0.2665% and occurs at a wavelength of 1175 nm, and the transmittance for the wavelength between 900 nm to 1250 nm is in the range between 5.3009% to 0.3052%.
2. The minimum transmittance of the optical lens assembly comprising the five pieces of the imaging lens (formed with 8 layers of the optical thin film on the both object-side and image-side surfaces) of Embodiment II is 0.0038% and occurs at a wavelength of 1075 nm, and the transmittance for the wavelength between 900 nm to 1250 nm is in the range between 0.1972% to 0.0349%.
3. The minimum transmittance of the optical lens assembly comprising the four pieces of the imaging lens (formed with 12 layers of the optical thin film on the both object-side and image-side surfaces) of Embodiment III is 0.000031% and occurs at a wavelength of 1025 nm, and the transmittance for the wavelength between 900 nm to 1250 nm is in the range between 0.008269% to 0.147179%.
4. The minimum transmittance of the optical lens assembly comprising the three pieces of the imaging lens (formed with 12 layers of the optical thin film on the both object-side and image-side surfaces) and one piece of the imaging lens (formed with 6 layers of the anti-reflection thin film on the both object-side and image-side surfaces) of Embodiment IV is 0.001094% and occurs at a wavelength of 1050 nm, and the transmittance for the wavelength between 900 nm to 1250 nm is in the range between 0.081021% to 0.578273%.
5. The minimum transmittance of the optical lens assembly comprising the two pieces of the imaging lens (formed with 12 layers of the optical thin film on the both object-side and image-side surfaces) and two pieces of the imaging lens (formed with 12 layers of the optical thin film on the object-side surface and 6 layers of the anti-reflection thin film on the image-side surfaces) of Embodiment V is 0.000111% and occurs at a wavelength of 1050 nm, and the transmittance for the wavelength between 900 nm to 1250 nm is in the range between 0.052406% to 0.223864%.
6. The minimum transmittance of the optical lens assembly comprising the three pieces of the imaging lens (formed with 14 layers of the optical thin film on the both object-side and image-side surfaces) of Embodiment VI is 0.000091% and occurs at a wavelength of 1025 nm, and the transmittance for the wavelength between 900 nm to 1250 nm is in the range between 0.007471% to 0.636851%.
7. In summary, the minimum transmittance of the optical lens assembly formed with the optical thin films of example embodiments falls in the wavelength range between 900 nm to 1250 nm, and for the wavelength range between 900 nm to 1250 nm, the value of the transmittance is not greater than 6%.
Therefore, a lower transmittance for the IR light can be achievable by a greater total amount and thicker total thickness of the optical thin films on the imaging lens, which enables the optical lens assembly to filter the IR light.
Additionally, for the incident light with wavelength between 450 nm to 650 nm, all of the imaging lens and the optical lens assembly of the aforesaid embodiments are operable to provide transmittance of over 80%. In some embodiments, such as the imaging lens of Embodiment I, a transmittance of greater than 90% is achievable. As such, example embodiments are operable to achieve high transparency of visible light.
Hence, through the layered structure of the optical thin films on at least one of the object-side surface and image-side surface of the imaging lens, which accumulatedly filters the IR light band in the spectrum, example embodiments of the imaging lenses satisfy the conditions as follows: (a) for incident light with wavelength between 500 nm to 1300 nm, a minimum transmittance of the imaging lens falls within a range between 900 nm and 1250 nm; (b1) for incident light with wavelength between 900 nm to 1250 nm, transmittance of the imaging lens is not greater than 60%; and (c) for incident light with wavelength between 450 nm to 650 nm, transmittance of the imaging lens is greater than 80%. Furthermore, example embodiments of the optical lens assembly assemblies satisfy the conditions as follows: (a) for incident light with wavelength between 500 nm to 1300 nm, a minimum transmittance of the optical lens assembly falls within a range between 900 nm and 1250 nm; (b2) for incident light with wavelength between 900 nm to 1250 nm, transmittance of the optical lens assembly is not greater than 10%; and (c) for incident light with wavelength between 450 nm to 650 nm, transmittance of the optical lens assembly is greater than 80%. As such, example embodiments of the optical lens assembly and imaging lens are operable to filter the IR light with the imaging lens to reduce the undesirable effect of the IR light, which would affect the image quality, and such embodiments do not require any additional IR filter. As such, a reduction in total length of the optical lens assembly is achievable.
While various embodiments in accordance with the disclosed principles have been described above, it should be understood that they have been presented by way of example only, and are not limiting. Thus, the breadth and scope of exemplary embodiment(s) should not be limited by any of the above-described embodiments, but should be defined only in accordance with the claims and their equivalents issuing from this disclosure. Furthermore, the above advantages and features are provided in described embodiments, but shall not limit the application of such issued claims to processes and structures accomplishing any or all of the above advantages.
Additionally, the section headings herein are provided for consistency with the suggestions under 37 C.F.R. 1.77 or otherwise to provide organizational cues. These headings shall not limit or characterize the invention(s) set out in any claims that may issue from this disclosure. Specifically, a description of a technology in the “Background” is not to be construed as an admission that technology is prior art to any invention(s) in this disclosure. Furthermore, any reference in this disclosure to “invention” in the singular should not be used to argue that there is only one piece of point of novelty in this disclosure. Multiple inventions may be set forth according to the limitations of the multiple claims issuing from this disclosure, and such claims accordingly define the invention(s), and their equivalents, that are protected thereby. In all instances, the scope of such claims shall be considered on their own merits in light of this disclosure, but should not be constrained by the headings herein.
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| Entry |
|---|
| Office Action from China Patent Application No. 201210145528.9 dated Feb. 2, 2015. |
| Number | Date | Country | |
|---|---|---|---|
| 20130301136 A1 | Nov 2013 | US |
