ASTM_C_1651_-_11.pdf

Designation:C165111Standard Test Method forMeasurement of Roll Wave Optical Distortion in Heat-Treated Flat Glass1This standard is issued under the fixed designation C1651;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method is applicable to the determination ofthe peak-to-valley depth and peak-to-peak distances of theout-of-plane deformation referred to as roll wave which occursin flat,heat-treated architectural glass substrates processed in aheat processing continuous or oscillating conveyance oven.1.2 This test method does not address other flatness issueslike edge kink,ream,pocket distortion,bow,or other distor-tions outside of roll wave as defined in this test method.1.3 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 Reference to these documents shall be the latest issueunless otherwise specified by the authority applying this testmethod.2.2 ASTM Standards:2C162 Terminology of Glass and Glass ProductsC1036 Specification for Flat GlassC1048 Specification for Heat-Strengthened and Fully Tem-pered Flat Glass3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 peak-to-valley depth of roll wavecharacteristicdepth,W,of roll wave as illustrated in Fig.1.3.1.2 peak-to-peak wavelength of roll wavecharacteristiclength,L,of roll wave shown as a sine-wave representing thedeformed surface section as illustrated in Fig.1.3.1.3 roll waveA repetitive wave-like departure fromflatness in glass that results from heat treating the glass in ahorizontal roller hearth furnace.Roll wave excludes edgeeffects such as edge kink and distortion influenced by assemblyor installation.3.1.4 roll wave optical distortionvisual distortion,D,thatresults from roll wave and expressed as lens power as in Eq 1.3.1.5 valley-to-valleywavelengthofrollwavecharacteristic length,L,of roll wave shown as a sine-waverepresenting the deformed surface section as illustrated in Fig.1.4.Summary of Test Method4.1 This test consists of moving an instrument across theglass surface in a direction parallel to the direction that theglass substrate traveled during heat processing.The instrumentwill primarily measure the out-of-plane deformation of theglass surface which is characteristic of the glass and known as“roll wave”.The peak-to-valley depths of the roll waves,W,and the peak-to-peak distances,L,are measured.(See Fig.1.)4.1.1 Other out-of-plane deformations of the glass surfacemay also be present which do not have the same peak andvalley wave character of the roll wave,but which also result inthe appearance of optical distortion in the glass.4.1.2 The optical distortion due to the out-of-plane defor-mation of the surface is measured as an optical power,similarto the optical power of a cylindrical mirror or lens.4.1.3 For those deformations that do have a wave character,the distortion can be calculated using the following formula.From the measured roll wave depth,W and the measuredpeak-to-peak or valley to valley wavelength of the roll wave,L,the optical roll wave distortion D is:D 5 42W/L2(1)where W and L are in metres and D is in diopters.Thedimensions of diopters(dpt)is m-1.The more usual unit of1This test method is under the jurisdiction of ASTM Committee C14 on Glassand Glass Products and is the direct responsibility of Subcommittee C14.11 onOptical Properties.Current edition approved Oct.1,2011.Published October 2011.Originallyapproved in 2008.Last previous edition approved in 2009 as C165109.DOI:10.1520/C1651-11.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 optical distortion is millidiopters which are obtained by mul-tiplying the value in diopters by 1 000.4.2 Appendix X1 and references show the relationshipbetween W,L,the measured radius of curvature R and theoptical distortion of a reflecting surface,D.5.Significance and Use5.1 This test method is a procedure for determining thepeak-to-valley depth and the wavelength of roll wave in flatglass and then calculating the optical distortion resulting fromthat roll wav