1、MIL-C-675C22 August 1980SUPERSEDINGMIL-C-675A6 January 1964MIL-C-00675B(MU)22 January 1976MILITARY SPECIFICATIONCOATING OF GLASS OPTICAL ELEMENTS(ANTI-REFLECTION)This specification is approved for use by all Departments and Agencies ofthe Department of Defense.1. SCOPE1.1 Scope. This specification e
2、stablishes the minimum optical anddurability requirements for magnesium fluoride interference films used asanti-reflection coatings on optical materials.2. APPLICABLE DOCUMENTS2.1 The following documents, of the issue in effect on date of invi-tation for bids or request for proposal, form a part of
3、this specificationto the extent specified herein:SPECIFICATIONSFederalL-T-90CCC-C-440MilitaryMIL-E-12397MIL-O-13830MIL-I-45607Tape, Pressure-Sensitive Adhesive Cellophane andCellulose AcetateCloth, Cheesecloth, Cotton Bleach and UnbleachedEraser, Rubber-Pumice for Testing Coated OpticalElementsOptic
4、al Components for Fire Control Instruments;General Specification Governing the Manufacture,Assembly and Inspection ofInspection Equipme(,t,Acquisition, Maintenanceand Disposition ofBeneficial comments (recommendations, additions, deletions), and any pertinent datawhich may be of use in improving thi
5、s document, should be addressed to: Commander,US Army Armament Research and Development Command, ATTN: DRDAR-TST-S,Dover, New Jersey 07801, by using the self-addressed Standardization DocumentImprovement Proposal (DD Form 1426), appearing at the end of this document, orby letter.FSC-6650Provided by
6、IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-C-675CSTANDARDSMilitaryMIL-STD-105 Sampling Procedure and Tables for Inspection byAttributesMIL-STD-109 Quality Assurance Terms and DefinitionsMIL-STD-1241 Optical Terms and DefinitionsDRAWINGSU.S. Army Armamen
7、t CommandC7641866 Surface Quality Comparison StandardsD7680600 Coating Quality Comparison StandardsD7608606 Coating, Eraser AbraslimTester(Copies of specifications, standards, drawings and publications requiredby suppliers in connection with specific procurement functions should beobtained from the
8、procuring activity or as directed by the contractingofficer.). t - 2.2 Other publication. :The followingjdocunt forms a part of-. -. - this specification to thextent specified-herein= Unless otherwise in-dicated, the issue in effect on date of invitation for bids or requestfor proposal shall apply:”
9、AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM)ASTM B l17-73-Standard Method of Salt Spray (fog) Testing(Applications for copies should be add;essed to the American Society forTesting and Materials, 1916 Race,Street,.Philadelphia, PA, 19103. Tech-nical society and technical association specificati
10、ons and standards aregenerally available for reference from libraries. They are also dis-tributed among technical groups and using Federal Agencies.)3. REQUIREMENTS3.1 Optical terms and definitions.- Terms and definitions peculiarto the general field of optics as used herein are defined in MIL-STD-1
11、241and Section 6.3 of this specification.3.2 Materials.- The material used for coating shall be a pure gradeof Magnesium Fluoride adequate to meet all requirements of this specifi-cation.,/-)3.3 Coated area.- Optical components shall be coated over their en-tire clear aperture. In those instances wh
12、ere the clear aperture is notspecified on the component drawing or procurement document the followingallowable uncoated holding area shall apply:Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-C-675CDiameter or MaximumDiagonal Dimensionof ODtical
13、 ElementMaximum Width ofUncoated Areaup to 2“Greater than 2“0.040”0.040” plus additionalwidth of 0.015”for each inchin diagonalgreater than 2“OR ORUp to 5 CM 1 MMGreater than 5 CM 1 MM plus additionalwidth increasing at therate of 0.15 MM foreach CM over 5 CMIn those instances where the clear apertu
14、re is specified, areas outside theclear aperture may be coated at the discretion of the contractor.3.4 Coating quality.- The coating shall be uniform in quality andcondition and shall conform to the following:3.4.1 Physical.- The coating shall show no evidence of deterioration- such as flaking, peel
15、ing, cracking or blistering.3.4.2 Cosmetic.- No stains, smears, streaks, or cloudiness shall bepermitted on optical components lying in a focal plane beyond those per-mitted by the component drawing. Unless otherwfse specified on the com-ponent drawing or procurement document, visual discolorations
16、such asstains, smears, streaks, cloudiness, etc. on optical components which lieoutside a focal plane in an optical system shall be acceptable when thestained area of the coated component conforms to the following:a. The transmission and/or reflection requirements of 3.5and 3.7.b. The adhesion requi
17、rement of 3.8.5.c. The severe abrasion resistance requirement20f 3.8.4.1 forsubstrates having a Knoop hardness greater than 450 kg/mm ; or the abra-sion resistance requirement 9f 3.8.4.2 for substrates having a Knoophardness less than 450 kg/mm .NOTE: For purposes of this specification, should a que
18、stion arise as towhether an optical component lies at or outside the focal plane,it will be assumed that it lies at the focal plane.3.4.3 Spatter and holes.- Coating spatter and holes shall be con-sidered as a dig and shall not exceed the allowable dig size and qualitystated on the component drawing
19、 or procurement document.3.4.4 Surface defects (scratch and dig).- Coating scratches anddigs shall not exceed the values specified for the substrate on the com-ponent drawing or procurement document. (k)dting scratches and digs shall3Provided by IHSNot for ResaleNo reproduction or networking permitt
20、ed without license from IHS-,-,-MIL-C-675C3.5 Transmission.- The increase in transmission of an element aftercoating at the wavelength that corresponds to a coating with a quarterwave optical thickness (QWOT) (See 6.3) shall be equal to or greater thanthe value specified in Figure 1, as applicable t
21、o the substrates re-fractive index and surface(s) coated.3.6 Film thickness.- Unless otherwise specified on the componentdrawing or procurement document, the coating shall have a QWOT between0.45 umand 0.60 urn(See 6.2).3.7 Reflectance (at the minimum point).- The magnitude of the specu-lar reflecta
22、nce for each coated surface at the minimum point on thespectal reflectance curve shall not exceed the values shown in Figure 2,according to the refractive index of thesutstrate.3.8 Durability.3.8.1 Salt solubility.- After immersion in a saline solution for aPeriod of 24 hours, the coated surface sha
23、ll meet the requirement of3.4.1 and the applicableabrasionresistance requirement of 3.8.4.3.8.2 Humidit+-After exposure to an atmosphere of 120 4F(48.90 + 2. C and 95 to 100% relative humidity, the coated surfaceshall met the requirements of 3.4.1 and the applicable abrasion resis-tance requirement
24、of 3.8.4.3.8.3 Salt spray fo- After exposure to a salt spray fog for acontinuous period of 24 hours, the coated surface shall meet the require-ments of 3.4.1 and the applicable abrasion resistance requirements of3.8.4.3.8.4 Abrasion resistance.3.8.4.1 Severe abrasion.- There shall be no visible dama
25、ge, suchas evidence of abrasion or coating removal, to the coated surface whenabraded by an eraser conforming to MIL-E-12397. The requirement shallbe performed oz substrate materials that have Knoop hardness greaterthan 450 kg/mm .3.8.4.2 Moderate abrasion.- There shall be no visible damage, suchas
26、evidence of abrasion or coating removal, to the coated surface whenabraded by a dry, clean, cheesecloth pad. The requirement shall be per-formed on2substrate materials that have a Knoop hardness less than450 kg/mm .3.8.5 Adhesion.- The coated optical surface shall show no evidenceof coating removal
27、when cellophane tape is pressed firmly against thecoated surface and quickly removed at an angle normal to the coatedsurface.4. QUALITY ASSURANCE PROVISIONS#4.1 Responsibility for inspection.- Unless otherwise specified inProvided by IHSNot for ResaleNo reproduction or networking permitted without l
28、icense from IHS-,-,-!IIL-C-675Cw-: - . . - - -. . -. . .- .-. 2In- -wi_., !: -., -.I zb - -i 00. . “Cncd2-% -.-%-1. .!: . .I,-!0-.-E-m-zH0m- . . -.-i-. . .Z I34“A-: .1 -. :- .- _l .1. - - . .- .-. - . .-. . . . . .-. .- $;.-.1!0- - . 1“ -J.-. - .4I1x. : .:-:/”:i1/ - J. _ _ 41, I:- - - - . -. .j - j-
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30、-. .1 . . . . . . . . Ii. . . . . . . . . .- . . .1 1 n 4 . . . . . . . .U2o. 11. i.!. l. 1:1 “/1 :“1-4-+-” -w-+-=”-!“-T”-i-”-.c, I , , , , 4.iC. .1fI -t-“” ”-11:.r.- 1 I- . -.0I,1:,.i.-:.“-:i-.-: - - “ - “” -l-i: :i !:0Ln 0 u-l 0 U-1 0 u-lh a0.t- a mIn 4(5(Provided by IHSNot for ResaleNo reproducti
31、on or networking permitted without license from IHS-,-,-MIL-C-675Cthe contract or purchase order, the supplier is responsible for the per-formance of all inspection requirements as specified herein. Except asotherwise specified, the supplier may utilize his own facilities or anyother facilities suit
32、able for the performance of the inspection require-ments specified herein, unless disapproved by the Government. TheGovernment reserves the right to perform any of the inspectio set forthin the specification where such inspections are deemed necessary to as-sure that supplies and services conform to
33、 prescribed requirements (See6.2).4.1.1 General provisions.- Definitions of inspection terms shallbe as listed in MIL-STD-109.4.1.2 Witness piece.- Unless otherwise specified, witness piecesas defined in 4.1.3 or coated components may be used to test the op-tical and durability requirements of the c
34、oated component (See 4.2, 4.3and 6.2). The witness pieces shall be positioned in the coating chambersuch that they represent the optical and durability characteristics ofthe whole evaporated lot (See 6.3). The Government reserves the rightto test the actual coated component with the same test to whi
35、ch the wit-ness pieces were subjected, except in the case where th known Knoop5hardness of the coated component is less than 450 kg/mm , the moderateabrasion test of 4.5.11 shall be utilized. Should a component fail, eventhrough the representative witness pieces pass the test, the lot shallbe reject
36、ed.4.1.3 Characteristics of the witness piece.- When the witnesspieces are used to test the optical and durability requirements of thecoated component they shall exhibit the following characteristics:The witness piece shall be such that it presents no dif-ficulty in ;asuring and testing the optical
37、and durability requirementsof the coating.b. The witness piece shall have a surface finish similarto that of the component to be coated.c. The witness piece shall simulate the axial thickness ofthe component by either computational methods or using a witness piecethat has the same thickness as the c
38、oated component for the measurementof transmission characteristics.d. The witness piece shall have a Knoop hardness greaterthan 450 kg/mm2 and be a low staining material.NOTE: When the refractive index and absorption coefficient of the wit-ness piece differs from that of the component, the transmiss
39、iondifference between the coated and uncoated witness piece shallconform to Figure 1; the reflectance of the quarter wave opticalthickness (QWOT) coating on the witness piece shall be equal toor less than the value specified in Figure 2.Provided by IHSNot for ResaleNo reproduction or networking perm
40、itted without license from IHS-,-,-MIL-C-675C4.2 First article (initial production) approval.- The requirementfor first article approval and the responsibility (government or con-tractor) for first article testing shall be as specified in the contract(See 6.2). Unless otherwise specified, the sample
41、 for first articleapproval tests shall consist of five (5) coated components, plus fif-teen (15) coated witness pieces (See 4.1.2 and 4.1.3). The five (5)coated components shall be tested as specified herein, for all the re-quirements of 3.3, 3.4.1, 3.4.2, 3.4.3 and 3.4.4. The fifteen (15)coated wit
42、ness pieces shall be divided into three (3) groups. Eachgroup shall consist of five (5) each coated witness pieces. One groupof five (5) coated witness pieces shall be tested, as specified herein,for all the requirementsof 3.5, 3.6, 3.7, 3.8.1, and 3.8.4.1. Thesecond group of five (5) coated witness
43、 pieces shall be tested, as speci-fied herein, for all the requirements of 3.5, 3.6, 3.7, 3.8.2 and 3.8.4.1.The third group of five (5) coated witness pieces shall be tested, asspecified herein, for all the requirements of 3.5, 3.6, 3.7, 3.8.3 and3.8.4.1. Except as noted herein, the government reser
44、ves the right tosubject the coated components to all the tests specified. The sampleshall be coated in the same manner using the same materials, equipment,processes and procedures as used in regular production. All materialsshall be obtained from the same source of supply as used in regularproductio
45、n.4.2.1 Government testin.- When the government is responsible forconducting first article approval tests, the contractor, prior to sub-mitting the sample to the Government, shall inspect the sample to insurethat it conforms to all the requirements of the contract and submit arecord of this Inspecti
46、on with the sample, including certificates ofconformance for materials, as applicable. :4.2.2 Contractor testinq .- When the contractor is responsible forconducting first article approal tests, the sample shall be inspectedby the contractor for all the requirements of the contract. The sampleand a r
47、ecord of this inspection, including certificates of conformancefor materials, shall be submitted to the Government for approval. TheGovernment reserves the right to witness the contractors inspection.4.3 Inspection provisions.-4.3.1 Submission of product.4.3.1.1 Insr3ectionlot size.- The inspection
48、lot size shall con-sist of all components or subassemblies (unit of product) coated withinone (8 through 12 hour) work shift.4.3.1.2 Lot formation and presentation of lots.- the unit of pro-duct shall be submitted for inspection on a movinclinspection lot basiswhere the components or subassemblies are continuusly”offered for in-spection in the order produced.NOTE: Each evaporation lot (coated components and witness pieces) forminga part of a moving inspection lot shall be identified for subse-quent evaluation, if requ
