1、1李艳龙李艳龙Fundamentals on Optical Coating2Contentsn1. A Brief Introduction on Coating and Coating systemsn2. Rudiments of Coating systemsn3. The principle and effect of evaporation sourcen4. Know-Hows of coatingn5. Coating process and film thickness monitoringn6. Optical knowledge and coating processn7
2、. Coating materials3nPart 1. A Brief Introduction on Coating and Coating systems4Know-how on CoatingqCoating materialsqSubstratesqFilm forming5Optical film coating materialsTransparent rangeRefractive indexEvaporation methods6Categories of substrates：Glass, Ceramics, Metals, Crystals, and PlasticCle
3、aning of substrates：Detergent, Chemicals, Ultrasonic cleaning, ionic bombardment, Heating, Steam-cleaning, UV cleaning and Ozone cleaning, etc.7Film formingChemicallyPhysicallyChemical vapor depositionPlatingElectrolysisAnodizingetc.Vacuum vapor depositionIon platingSputteringMBEetc.8蒸鍍(Evaporation)
4、 &濺鍍(Sputtering) 9Film Deposition1SprayingSubstrateMaterial2ElectroplatingSubstrateMaterialAnodeCathode3EvaporationMaterialSubstrateHeaterVacuum chamberCloud4SputteringMaterialSubstratePlasma10Thin Film DepositionnThe mechanism of thin film deposition involves electronicals (electrodes?) and semi-co
5、nductors. To take advantage of certain properties of the materials, films formed by some materials will be coated on the surface of substrates. The film forming process is thus called thin film deposition.11PVDPhysical Vapor DepositionnPVD means thin film deposition conducted by physical rules inste
6、ad of chemical interaction.nEvaporation and Sputtering are two of the most commonly applied PVD methods.1EvaporationMaterialSubstrateHeaterVacuum chamberCloud2SputteringMaterialSubstratePlasma12Ways to Realize Evaporation and Sputtering13Evaporation SystemsMaterialSubstrateHeaterVacuum chamberCloud1
7、4Coating systems chamber15Coating systems chamber16Evaporation AccessoriesnFilamentsnW boatsnMo boats17SputteringMaterialSubstratePlasma18PLASMAThe Fourth Habtitus of Substance19The nature of plasman1. As a whole, the plasma is in a neutral status, that means the negative particles and positive part
8、icles are equal in amount.n2. The plasma is constituted by many particles, so when some of the particles are affected, others or the whole plasma will be also effected. This is called Group Effect of Plasma.n3.Thermal and electric conduction20Principle on sputtering (examplary)n1. Ar Atomic dissocia
9、tionAr Ar+ e 2. Electron is accelerated to anode status, during the process, new dissociation will take place.n3. Ar ion is accelerated as cathod to strike out the target particle to form a film on the surface of the substrates.21SputteringVacuum pumpTakes place in a vacuumchamberElectrical charge i
10、s formed between the substrate and cathodeGas is injected in chamberIons hit the target andknock off atomsTarget atoms land (condense) on substrate to form a thin filmTarget Material(Cathode)SubstrateEnergyIons move in plasmaGasPlasmaGas ionizes - forms a plasma22Target Erosion23Introduction on Vacu
11、um Coating Systems:n 1.Vacuum systemsn 2.Evaporation systemsn 3.Control systemsn 4.Aid systems241. Vacuum System25Vaporation systems：Thermal systemsSputteringIAD Ion Aid Deposition26A Sketch on Coating systemsn1 Heatingn2 Glassn3 Evaporation sourcen4 Phosphorizer27Thermal evaporation28Electron Beam
12、EvaporationElectron beam evaporation is a form of thermal evaporation, and also the most commonly applied method to create thin films.29Sketch on Electron gun30APS1104Leybold3132APS1104 Vacuum chamber33 Lenses holder34 IAD - Ion Aid DepositionnIAD At the same time when electron beam evaporation is t
13、aking place, ions are used to strike the thin film to make a better constitution. This process is called IAD. 35Reactive Ion Plating nRIP is a process of combined evaporation: in the process of electronic gun evaporation, both the evaporated source material and plasma source filament are dissociated
14、 into plasma gasnIons and source material in the plasma ionization are accelerated in the electric field into the vapor discharge plasma nMeanwhile the ions and electrons are colliding to each other and reacted to form a film on the surface of the substrates.363. Control SystemsTimingColorOptical co
15、ntrolQuartz crystals vibration control37Optical Thin Film Thickness Monitoring Systems38The principle of monitoring thin film thickness by quartz takes advantage of two characteristics (effects) of quartz crystals: Piezoelectric effect; and Quality loading effect.39Aid SystemsHeating: The measuremen
16、t and control of temperatureGas puffing: The measurement of vacuum level and pressure control Work rest: Revolution and rotation of the subjectIonic bombardment: Direct current and ion radiationSamples shelf: transmission, reflection40The Optical Property of Thin Films: Transmission Reflectivity Pol
17、arization measurement41nPart 2. Rudiments of Coating Systems421. The meaning and characteristics of vacuumVacuum is the status of a given space, in which air is less than atmospheric pressure. The thin air status is often called a vacuum.2. Technologies involving vacuum1.As the density of air decrea
18、ses, the physical properties of air changes. It is based on the change of property in the application of vacuum.43真空状态真空状态 气体性质气体性质 应用原理应用原理 应用概况应用概况 Rough Vacuum105 103（Pa） 76010（Torr） 气体状态与常压相比较只有分子数目由多变少的变化，而无气体分子空间特性的变化分子相互间碰撞频繁 利用真空与大气的压力差产生的力及感差力均匀的原理实现真空的力学应用 1. 真空吸引和输运固体、液体、胶体和微粒； 2. 真空吸盘起重、
19、真空医疗器械； 3. 真空成型，复制浮雕； 4. 真空过滤； 5. 真空浸渍。 低真空 103 10-1（Pa） 1010-3（Torr） 气体分子间，分子与器壁间的相互碰撞不相上下，气体分子密度较小 利用气体分子密度降低可实现无氧化加热利用气压降低时气体的热传导及对流逐渐消失的原理实现真空隔热和绝缘 利用压强降低液体沸点也降低的原理实现真空冷冻真空干燥 1. 黑色金属的真空熔 炼 ， 脱气 、 浇铸和热处理 2. 真空热轧、真空表面渗铬； 3. 真空绝缘和真空隔热； 4. 真空蒸馏药物、油类及高分子化合物； 5. 真空冷冻、真空干燥； 6. 真空包装、真空充气包装； 7. 高速空气动力学实验
20、中的低压风洞 高真空10-1 10-6（Pa） 10-310-8 （ Torr ） 分子间相互碰撞极少、分子与器壁间碰撞频繁 气体分子密度小 利用气体分子密度小任何物质与残余气体分子的化学作用徽弱的特点进行真空冶金、真空镀膜及真空器件生产 1. 稀有金属、超纯金属和合金、半导体材料的真空熔炼和精制；常用结构材料的真空还原冶金； 2. 纯金属的真空蒸馏精练；放射性同位素蒸发； 3. 难熔金疆的真空烧结； 4. 半导体材料的真空提纯和晶体制备； 5. 高温金相显微镜及高温材料实验设备的制造； 6. 真空镀膜，离子注入膜一刻蚀等表面改性真空镀膜，离子注入膜一刻蚀等表面改性； 7. 电真空工业的电光管
21、、离子管、电子源管、电子束管、电子衍射仪，电子显微镜、 x 光显微镜，各种粒了加速器、能谱仪、核辐射谱仪，中子管、气体激光器的制造； 8. 电子束除气、电子束焊接，区域熔炼，电子束加超高真空 10-1 10-6（Pa） 10-110-8（Torr） 气体分子密度摄低与器壁磋撞的次敌极少致使表面形成单分子层的时间增长 气态空间中只有固体本身的原子几乎没有其他原子或分子的存在。 利用气体分子密度极低与表面碰撞极少，表面形成单一分子层时间很长的原理实现表面物理与表面化学的研究 1. 可控热核聚变的研究； 2. 时间基准氢分子镜的制作； 3 .表面物理表面化学的研究； 4. 宇宙空间环境的模拟； 5.
22、 大型同步质子加速器的运转； 6. 电磁悬浮式高精度陀螺仪的制作。 44 The application of vacuum in coating area Vacuum coating technology is an important branch of vacuum application, and is widely applied in optics, electronics, energy, architecture, packaging, and scientific research, etc. 45Mechanical PumpMechanical pump is an e
23、quipment that takes advantage of the mechanical & physical principles to pump out the air of a container.464748495051Lobe Pump52Oil Diffusion Pump53 Cryocondensation Pump54The measuring tool of vacuum levelnVacuum gauge555657In the range of 1010-1 Pa, the connection between the thermal conductivity
24、and atmospheric pressure is obvious.In the range of 10-210-6Pa离子流正比与气压，这就是它的测量范围 (this range is the measuring range of ion current proportional to atmospheric pressure) 58596061A complete vacuum system constitute the followings: Pumps Vacuum valves Adjoining pipeline Vacuum level measurement tools A
25、ccessories62Part 3.The Principle and Effect of Evaporation Source63 Heat-Resistant Source: Electrify boats or filaments made by refractory metals such as W, Ta to heat the material have been placed on them. This is mainly to evaporate Pb, Ag, Al, Cu, Cr, Au, Ni etc. 64Part 4. Know-Hows of Coating65T
26、he micro version of thin filmsColumn structuresTumors66The assembling density of thin film is important because it effects the firmness, hardness, moist-resistance, scattering, and absorption of light of the thin film.柱状结构柱状结构The Column Structure of Thin Film:Improving the micro-structure of thin fi
27、lm is one of the main goals in advancing the technologies of coating67Part 5. Coating Process and Film Thickness Monitoring68Methods to Monitor Thin Film ThicknessnOptical thin film thickness monitor Passing through method Reflection methodnQuartz thin film thickness monitor 5M 6M69Optical thin film
28、 thickness monitor 透過式Via passing through the thin film70Optical thin film thickness monitor 反射式Via reflecting on the thin film7172Optical Thin Film Thickness MonitoringnAdvantagesRequires a lower stability of monitoring systems可以避免膜材折射率改變造成監控訊號變化幅度改變造成的問題。Easy to design the monitoring systems nDisa
29、dvantages無法執行極窄帶通的濾鏡監控Unable to monitor thickness of thin film in a very narrow band-pass 73n Quartz Thin Film Thickness MonitorOscillating crystals Monitoring equipments74Part 6. Optical Knowledge And Coating Process75 【Spectrum】 The rainbow of colors in visible light when separated using a prism:
30、Visible light range is between 770380nm, colors including from red to violet. Lights beyond color red is called infrared, while beyond the color purple ultraviolet, both are invisible to human eyes.76Light rays at around 550nm is the most sensible light to human eyes, colors in yellow or green.77Wav
31、elength(m)Wavelength(nm)Wave number(cm-1)Far IF25100025000100000040010Mid IF2.5252500250004000400Near IF0.782.57802500128204000Red0.620.786207801612912820Orange0.60.626006201666716129Yellow0.580.65806001724116667Green0.50.585005802000017241Blue0.440.54405002272720000Violet0.380.443804402631622727Nea
32、r UV0.30.383003803333326316Mid UV0.20.32003005000033333Far UV0.1850.21852005405450000Vacuum UV0.010.1851018510000005405478Important Data in Optical Thin FilmnReflective datanTransparencynRefractionnChromatic dispersion79Reflection and TransparencyBK7 substrateAirAir100%91.5%Air N0=N1=1BK7 substrate
33、Ns=1.52A.O.I.=0R0s= N0-Ns2 N0+Ns201S=(1-1.52)2(1+1.52)2= 0.0425Rs1= Ns-N12 Ns+N12(1.52-1)2(1.52+1)2= 0.0425T=1-R0s-Rs1=0.9158.5%80Refraction N=C/V N: Refraction C: Velocity of light in vacuum V: Velocity of light in medium 81Chromatic DispersionThe phenomenon in which the phase velocity of a wavelen
34、gth depends on its frequency; or alternatively, when the group velocity depends on the frequency. Media having such a property are termed dispersive media. 82Typical Coatingsv Anti-reflective filmv Beam-splitting filmv Reflective filmv Filters83AR FilmPurposeoIncreases optical transmissionoDecreases
35、 strayed lightsoImproves the quality of imageoAdds the distance of effects84Single Layer AR Coating850510152025400450500550600650700750800Antireflection Coating 550 nm% ReflectanceWavelength (nm)Red line：1.38H 0.61LBlue line：0.31H 2.77L NH=1.7 NL=1.46Double Layers AR Coating - A860123454004505005506
36、00650700单层膜、/4-/4和/2-/2型双层增透膜理论曲线% ReflectanceWavelength (nm)Double layers AR coating - B87012345400450500550600650700K9基底上各种设计的增透膜理论曲线比较% ReflectanceWavelength (nm)Three-layered AR Coating88012345400500600700800900100011001200130014001500Antireflection coating at 532nm&1064nm% ReflectanceWavelength
37、 (nm)G.25453I .06773H .0459I .10938L .05389H .08113L .21788F Air I:1.7 H:2.3 L:1.46 F:1.38 89Beam-Splitting FilmApplications including:Optoelectronic equipments, medical devices, semi-conductors, & military.90Positions of Beam-Splitting91Prism Splitting1. NPBSNon- Polarization beam splitters2. PBSPo
38、larization beam splitters92金属分光镜金属分光镜9394950102030405060708090100200300400500600700800分光膜% TransmittanceWavelength (nm)The Comparism Of Single Zns Film And Five Films G/2LHLHL/Airg-K9 ; L-MgF2; H-Zns96020406080100400450500550600650700750800K9基底上分光膜理论曲线% TransmittanceWavelength (nm)The Polarization o
39、f Beam-splitting Plates97020406080100400450500550600650700K9棱镜分光膜理论曲线% TransmittanceWavelength (nm)The Polarization of Beam-splitting Prisms980102030405060708090100-050010001500200025003000350040004500500055006000650070007500800085009000950010000不同厚度Al膜的反射对比% ReflectanceWavelength (nm)The curve of A
40、l film on 1、2、4、8、16、32、64、128nm金Reflective Film99Metal Reflection Medium100Things To Consider On Chosing Metal Materialsq Wavelengthq Reflectionq Environmentq Cost Al: Commonly applied in UV, Visible and Infrared ranges Ag: High reflection, poor stability Au: Commonly applied in Infrared range, sta
41、blePt, Rh：Stable and firm10101020304050607080901002002503003504004505005506006507007508008509009501000 % ReflectanceWavelength (nm)Comparism On Spectrum Of Ag Film, Al Film, and Al+lhlh Film 102Filters 103Interference Filters104Band Pass Filters0Peak WavelengthTmaxPeak Transmission2 Pass-Band Half-W
42、idth: The wavelength on which the transmission is half of peak transmission105020406080100500520540560580600单半波与双半波滤光片光谱曲线% TransmittanceWavelength (nm)10610702040608010050010001500200025003000350040004500500055006000650070007500800085009000950010000诱导透射滤光片% TransmittanceWavelength (nm)108Part 7. Co
43、ating Materials1091. High Purity Oxides SiO、HfO2、ZrO2、TiO2、TiO、SiO2、Ti2O3、Ti3O5、Ta2O5、Nb2O5、Al2O3、Sc2O3、In2O3、Pr(TiO3)2、CeO2、MgO、WO3、Sm2O3、 Nd2O3、Bi2O3、Pr6O11、Sb2O3、V2O5、NiO、 ZnO、Fe2O、Cr2O3、 CuO、 Y2O3 etc.2.High Purity FluoridesMgF2、YbF3、LaF3、DyF3、NdF3、ErF3、KF、SrF3、SmF3、NaF、BaF2 CeF3 etc.1103. High
44、Purity Metals Al, Cu, Cr, Co, Ag, Pr, W, Si, Mn, Sn, V, Ti, Zr, Ni,Ta, Ir, etc. 4. MixturesZrO2+TiO2, ZrO2+Ta2O5, ZrO2+Al2O3, MgO+Al2O3, In2O3+Sn2O3, etc.5. Others BaTiO3、PrTiO3、SrTiO3、LaTiO3、ZnS、Na3AlF6、ZnSe etc.1116. Metal Targets Si target、 Nb target、 Ni target、Ti target、Zn target、Cr target、Mg ta
45、rget、Sn target、Al target ect.7. Ceramic Targets ITO target、AZO target、MgO target、SiO2 target、TiO2 target、Nb2O5 target、MgF2 target etc. 112FAQs Spits and stains are common problems in thin film coating, which will significantly affect the quality of the thin film and the lens. There are various facto
46、rs that cause this, please see the following113nCommon Reasons For SpitsnThe coating material is not pure enough, and the impurities in the material are evaporated onto the substrates; thus creating spits.nThe coating material is moisturized, and thus has not been completely melted in the process of
47、 coating.nThe pre-melt has not finished when the coating takes place.nRedundant electronic beam causes the material to spit.1142. Common Reasons To Cause StainsnThe lens and/or the accessories are not cleaned well.nOn multilayer coating, the first layer may be polluted due to inefficient cleaning, which causes stains on the layer(s) afterwards.nThe substrates are moisturized, and the moisture has vaporized in the heating before coating takes place.nMoisturized accessories may also affect the coating.115116117118119120121122123124125126Thank you! Thank you
