CN100416309C - Neutral density light filter - Google Patents

Neutral density light filter Download PDF

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Publication number
CN100416309C
CN100416309C CNB2005101252975A CN200510125297A CN100416309C CN 100416309 C CN100416309 C CN 100416309C CN B2005101252975 A CNB2005101252975 A CN B2005101252975A CN 200510125297 A CN200510125297 A CN 200510125297A CN 100416309 C CN100416309 C CN 100416309C
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China
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neutral density
density filter
substrate
characterized
rete
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CNB2005101252975A
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Chinese (zh)
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CN1971319A (en
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林信裕
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亚洲光学股份有限公司
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Abstract

The invention discloses a neutral density filter that comprises a base plate and several membranous layers mounted on one side of the base plate, the structure of the membranous layers are 0.4M3LmH1.25L0.25H1.25L, H expresses the high-index membranous layer which adopts the iron-nickel-chromium as membranous material; L expresses the low-index membranous layer that its material is SiO2; M expresses middle membranous layer that its refractive index is between the high-index membranous layer and the base plate, the middle membranous layer is as the first layer to be plated on surface of one side of the base plate; mH is darkness adjustment layer of the neutral density filter, m expresses a number determined by density of the neutral density filter and spectral transmittance.

Description

Neutral density filter

[technical field]

The present invention relates to a kind of neutral density filter (Neutral Density Filter, ND Filter), refer to the neutral density filter of the high concentration that a kind of flatness of its spectral-transmission favtor is splendid especially.

[background technology]

At present, optical filter has been widely used in being used for making these optical equipments can realize different optical functions in the optical equipments such as projector, traditional camera, digital camera, mobile phone, astronomical telescope.Spectral characteristic according to optical filter is divided, and mainly contains bandpass filter, cutoff filter, two to beam split optical filter, reflection filter and neutral density filter.Neutral density filter has certain optical density (OD), it can reduce the luminous flux on the solid-state photo-sensitive cells such as the sensitive film that incides optical equipment or CCD, difference according to its optical density (OD), its resistance to light subtracts effect and also has nothing in common with each other, but no matter its density size all can not change the COLOR COMPOSITION THROUGH DISTRIBUTION of light.For example: when under the strong environment of sunlight, taking pictures, want, can before camera lens, install neutral density filter additional the dim light effect is provided when fast inadequately but the speed of shutter is limited with large aperture.

Neutral density filter with constant density can weaken the light of all wavelengths without exception, and promptly the spectrum of all in visible-range has consistent light transmission.The neutral density filter of relevant constant density can be consulted by United States Patent (USP) the 5th, 715, and No. 103, the 6th, 842,302B2 number and the 6th, 842, the content that is disclosed for 301B2 number.

By United States Patent (USP) the 5th, 715, the neutral density filter that is disclosed for No. 103 is to form an insulating film layer that is made of the multi anti reflection coating floor on substrate, and the material of this multi anti reflection coating layer is from Al 2O 3, MgF 2And SiO 2In select, and the side that optical filter contacts with air is a MgF 2Rete.

By United States Patent (USP) the 6th, 842,302B2 number and the 6th, 842, the neutral density filter that is disclosed for 301B2 number is that a nickel-chrome rete and a SiO are set on a transparent plastic base 2Rete, and a MgF is set at the top 2Rete, wherein this nickel-chrome rete contains 90% metallic nickel and 10% crome metal, and SiO 2Rete then serves as the antireflection rete.Yet, nickel-chrome rete and SiO 2The rete common neutral density filter less stable that constitutes that combines, and make corresponding processing procedure more complicated.

TiO is mostly adopted in the system plating of above-mentioned existing neutral density filter 2After inadequate enough oxygen produces absorption effect, and Al 2O 3, MgF 2Collocation is finished mutually.But in the above-mentioned prior art and not mentioned film arrangement architecture whether be symmetry.In addition, this system electroplating method is the processing procedure complexity not only, and must think over and calculate because oxygenation capacity is not enough and may cause TiO 2The instability of uptake, and easily the spectrophotometric result of finished product is caused harmful effect.

Recently, the raising along with the sensitivity of photographic goods can further reduce the optical transmission rate by the concentration that increases the weight of neutral density filter, thereby make aperture openings to increase.But, if is that difference with maximum transmission rate value (Tmax) and minimum transmittance value (Tmin) multiply by 8 percent less than average transmittance value (Tavg) with existing neutral density filter for the requirement of transmissivity flatness, i.e. (Tmax-Tmin)<Tavg*8%, and the wavelength coverage of incident light is that 400~700nm is when calculating, because of the average transmittance value (Tavg) of the neutral density filter of high concentration is lower with respect to the average transmittance value (Tavg) of low concentration, thereby make that the gap value of (Tmax-Tmin) of high concentration is littler with respect to the gap value of (Tmax-Tmin) of low concentration.For example, when the density of neutral density filter equals 0.8, its average transmittance value (Tavg) is 15.8 o'clock, and the value of its flatness (Tmax-Tmin) is less than 1.25%; When the density of neutral density filter equals 1.6, its average transmittance value (Tavg) is 2.5 o'clock, and the value of its flatness (Tmax-Tmin) is less than 0.2%.

From above-mentioned analysis as can be known, it is more strict that the neutral density filter of high concentration requires to require for the flatness of spectral-transmission favtor compared to the neutral density filter of low concentration for the flatness of spectral-transmission favtor, and existing film layer structure is the flatness requirement that is difficult to satisfied neutral density filter to high concentration.Therefore, be necessary the film layer structure of existing neutral density filter is improved, with the flatness of the neutral density filter that improves present high concentration.

[summary of the invention]

The object of the present invention is to provide a kind of neutral density filter, it has the advantages that the flatness characteristic is good and dichroism is good.

According to above-mentioned purpose of the present invention, the invention provides a kind of neutral density filter, it has a substrate and is arranged at several retes of substrate one side, and this film layer structure is 0.4M3LmH1.25L0.25H1.25L, wherein H represents high refractive index layer, and it has adopted iron-nickel-chromium as the film material; L represents low-index film, and this rete material is SiO 2M represents the middle rete of refractive index circle between high refractive index layer and substrate, and this centre rete is directly to be sputtered on the surface of substrate one side as a first floor; And mH is that the concentration of this neutral density filter is adjusted layer, and m represents the numerical value that can determine according to the concentration and the spectral-transmission favtor of this neutral density filter.

On the opposite side surface of aforesaid substrate, also be provided with the rete that a structure is 0.4M3LmH1.25L0.25H1.25L.

M value in the above-mentioned film layer structure is into the equal proportion relation with the spectral-transmission favtor of neutral density filter, and concentration is big more, and described m value is just big more, and spectral-transmission favtor is just low more.The every reduction by 2.5% of spectral-transmission favtor, m value just need to multiply by 1.4 on former numerical value.

The material refractive index of rete is between 1.8~2.2 in the middle of above-mentioned.

The content of the iron in the above-mentioned high refractive index layer, nickel, chromium is respectively: iron≤1%, nickel 〉=75% and chromium≤19.2%.

Aforesaid substrate can be pet substrate, PC or other plastic material, glass material and other transparent material.

Compared to prior art, neutral density filter of the present invention mainly is to utilize a material refractive index directly to be sputtered on the substrate surface as a first floor at the middle rete between 1.8~2.2, and iron-nickel-chromium and SiO again arrange in pairs or groups 2Pile up, also will implement double-sided coating to substrate simultaneously, the film layer structure that obtains in this way can be so that the flatness characteristic of neutral density filter of the present invention and dichroism be splendid.

[description of drawings]

Fig. 1 is the synoptic diagram of neutral density filter of the present invention and film layer structure thereof.

Fig. 2 be according to spectral-transmission favtor be 10% design neutral density filter the film layer structure gained be the family curve synoptic diagram of the spectral-transmission favtor between 400~700nm in wavelength coverage.

Fig. 3 be according to spectral-transmission favtor be 10% design neutral density filter the film layer structure gained be the family curve synoptic diagram of the spectral reflectivity between 400~700nm in wavelength coverage.

Fig. 4 is that the Design Theory value when spectral-transmission favtor is 10%, and only after the first face system plating to neutral density filter, the flatness characteristic synoptic diagram of the spectrum actual transmission after the optimization of gained.

Fig. 5 is that the Design Theory value when spectral-transmission favtor is 10%, and after neutral density filter carried out two-sided system plating, the flatness characteristic synoptic diagram of the spectrum actual transmission after the optimization of gained.

Fig. 6 is that the Design Theory value when spectral-transmission favtor is 10%, and after neutral density filter carried out two-sided system plating, the characteristic synoptic diagram of the actual reflectance after the optimization of gained.

[embodiment]

Please refer to shown in Figure 1, neutral density filter 1 of the present invention is the neutral density filter of a high concentration, it includes a substrate 10 and is sputtered at several retes 20 on the substrate 10, among the actual embodiment, rete can be the one or both sides that are coated on substrate respectively, and easy on illustrating only shown the plated film of substrate and one side in Fig. 1.

This neutral colour filter 1 employed substrate 10 can be glass substrate, transparent plastic substrate, acryl substrate or other transparency carrier, and in the present embodiment, what substrate 10 adopted is the PET plastic base, and substrate 10 thickness are about 100 μ m.Also can adopt PC or other plastic material, glass material and other transparent material.

Above-mentioned rete 20 is that the stack manner with 0.4M3LmH1.25L0.25H1.25L is coated on the substrate 10, wherein H represents high refractive index layer, it has adopted iron-nickel-chromium as the film material, the content of iron, nickel, chromium is respectively in this H rete: iron≤1%, nickel 〉=75% and chromium≤19.2%, and the optical thickness of 1H is 0.20, its physical thickness is 40nm, and centre wavelength is 440nm; L represents low-index film, and this rete material is SiO 2, and the optical thickness of 1L is 0.20, and its physical thickness is 60nm, and centre wavelength is 440nm; Reach M and represent the middle rete M of refractive index circle between H rete and pet substrate 10, its refractive index n equals 1.8~2.2.

In the present embodiment, at first be a middle rete M directly will be sputtered on the substrate 10 as the first floor, be alternately stacked in mutually on the rete M of this centre with low-index film L and high refractive index layer H again.The detailed structure of the rete 20 of Xing Chenging is that first rete is middle rete M in this way, second rete is a low-refraction L rete, and the tertiary membrane layer is high refractive index layer H, and the 4th rete is low-index film L, the 5th rete is high refractive index layer H, and the 6th rete is low-index film L.Wherein the middle rete M of first rete (0.4M) is that optical thickness with 1H is multiplied by 0.4 times thickness and is sputtered on the substrate; The low-index film L of second rete (3L) is that the optical thickness with 1L is multiplied by 3 times thickness and is sputtered on first rete; The high refractive index layer H of tertiary membrane layer (mH) is that the optical thickness with 1H is multiplied by m thickness doubly and is sputtered on second rete, and this rete (mH) be that the concentration of optical filter is adjusted layer, and the m value can be decided (being detailed later) according to the requirement of concentration needs and spectral-transmission favtor; The low-index film L of the 4th rete (1.25L) is that the optical thickness with 1L is multiplied by 1.25 times thickness and is sputtered on the tertiary membrane layer; The high refractive index layer H of the 5th rete (0.25H) is that the optical thickness with 1H is multiplied by 0.25 times thickness and is sputtered on the 4th rete; The low-index film L of the 6th rete (1.25L) is that the optical thickness with 1L is multiplied by 1.25 times thickness and is sputtered on the 5th rete.Carry out film stack in this manner and can obtain the splendid neutral density filter of spectral characteristic.

The occurrence of the thickness of each rete in the above-mentioned rete 20 can also be determined according to specific requirement and applied environment.

Tertiary membrane layer (mH) in the above-mentioned rete 20 is that concentration is adjusted layer, and the dense more m value of concentration is big more, and the dense more spectral-transmission favtor T of concentration (%) is just low more.T (%) is into the equal proportion relation with the m value, the every reduction by 2.5% of T (%), and the m value just needs to multiply by 1.4 on former numerical value.Preferably, can import the optimization of rete design software again, make neutral colour filter obtain better transmissivity flatness.Be that benchmark illustrates equal proportion relation between the two below with T=10%:

T=10% → m=0.4

T=7.5% → m=0.55

T=5% → m=0.75

T=2.5% → m=1.05

T=1% → m=1.5

According to spectral-transmission favtor is the rete 20 that T=10% designs neutral density filter 1, it is shown in Figure 2 to be in wavelength coverage that the spectral-transmission favtor family curve that can access between 400~700nm please refer to, and its spectral reflectivity family curve please refer to shown in Figure 3.Certainly, if spectral-transmission favtor is when being worth for other, as: 7.5%, 5%, 2.5%, 1% or other, also can obtain the splendid curve of flatness characteristic of spectral-transmission favtor, just its response curve is not presented one by one at this.

Above-mentioned process of plating can adopt general evaporation coating method system plating to form, but can be according to process conditions, to adjust the beam split flatness of neutral density filter of the present invention when the system plating.For example, after the first face system plating to neutral density filter, can obtain (Tmax-Tmin)<1% and R<2%, wherein Tmax represents that incident light passes through the maximum transmission rate value of neutral colour filter, Tmin represents that incident light passes through the minimum transmittance value of neutral colour filter, R represents reflectivity, and wavelength coverage is the flatness family curve synoptic diagram of the actual transmission of 400~700nm, as shown in Figure 4.

For further obtaining the flatness family curve better than design load, can also carry out two-sided system plating to neutral density filter 1 in the present embodiment, just can obtain the flatness characteristic (as shown in Figure 5) of (Tmax-Tmin)<0.5% and the reflectivity Characteristics (as shown in Figure 6) of R<2%, promptly the another side of substrate 10 also plate one with the identical rete of above-mentioned rete 20 structures, form complementary spectrophotometric spectra by this two-sided design, can obtain better transmitted light flatness characteristic.

Can carry out single face ND or the plating of two-sided ND system according to required specification and the concentration that is fit in addition; As above-mentioned, use two-sided system plating to have two-sided superposition complementary effect, obtain to be better than the splendid characteristic of transmitted light flatness of original design load.

Claims (17)

1. neutral density filter, it has a substrate and is arranged at several retes of substrate one side, and it is characterized in that: film layer structure is 0.4M3LmH1.25L0.25H1.25L, and wherein H represents high refractive index layer, and it has adopted iron-nickel-chromium as the film material; L represents low-index film, and this rete material is SiO 2M represents the middle rete of a refractive index between high refractive index layer and substrate, and this centre rete is directly to be sputtered on the surface of substrate one side as a first floor; And mH is that the concentration of this neutral density filter is adjusted layer, and m represents the numerical value that can determine according to the concentration and the spectral-transmission favtor of this neutral density filter.
2. neutral density filter as claimed in claim 1 is characterized in that: also be provided with the rete that a structure is 0.4M3LmH1.25L0.25H1.25L on the surface of substrate opposite side.
3. neutral density filter as claimed in claim 1 or 2 is characterized in that: the m value in the film layer structure is into the equal proportion relation with the spectral-transmission favtor of neutral density filter, and concentration is big more, and described m value is just big more, and spectral-transmission favtor is just low more.
4. neutral density filter as claimed in claim 3 is characterized in that: the spectral-transmission favtor of neutral density filter is a higher limit with 10%, every reduction by 2.5%, and the m value just needs to multiply by 1.4 on former numerical value.
5. neutral density filter as claimed in claim 1 or 2 is characterized in that: the material refractive index of middle rete is between 1.8~2.2.
6. neutral density filter as claimed in claim 5 is characterized in that: the content of the iron in the high refractive index layer, nickel, chromium is respectively: iron≤1%, nickel 〉=75% and chromium≤19.2%.
7. neutral density filter as claimed in claim 6 is characterized in that: substrate is a transparent plastic substrate.
8. neutral density filter as claimed in claim 6 is characterized in that: substrate is a pet substrate.
9. the neutral density filter of a high concentration, several retes that it has a substrate and is arranged at the substrate both sides, it is characterized in that: the film layer structure that is positioned at the substrate both sides is identical, and all be directly to be sputtered on the substrate surface as a first floor at the middle rete between 1.8~2.2, be alternately stacked in mutually on the corresponding middle rete with low-index film, high refractive index layer again with its material refractive index.
10. the neutral density filter of high concentration as claimed in claim 9, it is characterized in that: the film layer structure that is positioned at the substrate both sides is 0.4M3LmH1.25L0.25H1.25L, rete in the middle of wherein M represents, H represents high refractive index layer, L represents low-index film, and m represents the numerical value that can determine according to the concentration and the spectral-transmission favtor of neutral density filter.
11. the neutral density filter of high concentration as claimed in claim 10 is characterized in that: high refractive index layer is to have adopted iron-nickel-chromium as the film material.
12. the neutral density filter of high concentration as claimed in claim 11 is characterized in that: the content of the iron in the high refractive index layer, nickel, chromium is respectively: iron≤1%, nickel 〉=75% and chromium≤19.2%.
13. the neutral density filter of high concentration as claimed in claim 10 is characterized in that: the material of low-index film is SiO 2
14. the neutral density filter of high concentration as claimed in claim 10 is characterized in that: substrate is wherein one of pet substrate, PC or other plastic material, glass material and other transparent material.
15. the neutral density filter of high concentration as claimed in claim 10 is characterized in that: the mH layer in the film layer structure is that the concentration of this neutral density filter is adjusted layer, and concentration is big more, and described m value is just big more, and spectral-transmission favtor is just low more.
16. the neutral density filter of high concentration as claimed in claim 15 is characterized in that: the m value is into the equal proportion relation with spectral-transmission favtor.
17. the neutral density filter of high concentration as claimed in claim 16 is characterized in that: the spectral-transmission favtor of neutral density filter is a higher limit with 10%, every reduction by 2.5%, and the m value just needs to multiply by 1.4 on former numerical value.
CNB2005101252975A 2005-11-23 2005-11-23 Neutral density light filter CN100416309C (en)

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Publication number Priority date Publication date Assignee Title
CN101893729B (en) * 2010-07-22 2011-12-07 中国航空工业集团公司洛阳电光设备研究所 Intermediate infrared bandpass filter and preparation method thereof
CN104297833B (en) * 2014-11-06 2017-01-18 沈阳仪表科学研究院有限公司 Low-reflection and neutral-density filter

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Owner name: XINTHAI OPTICAL (SHENZHEN) CO., LTD.

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