ISO/TR TECHNICAL REPORT 18476 First edition 2017-06 Ophthalmic optics and instruments Free form technology Spectacle lenses and measurement Optique et instruments ophtalmiques - Technologie free form - Verres de lunettes et mesurage Reference number ISO/TR 18476:2017(E) International Organization for Standardization @ IS0 2017 see=ZHEJIANG INST OF STANDARDIZATION C1 5956617 No reproduction or networking permitted without license from IHS IS0/TR 18476:2017(E) COPYRIGHT PROTECTEDDOCUMENT IS0 2017, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISO's member body in the country of the requester. ISO copyright office Ch. de Blandonnet 8 . CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 [email protected] www.iso.org Licensee-ZHEJIANG INST OF STANDARDIZAISQ 017 - All rights reserVed HS und networking permited without license from IHS IS0/TR 18476:2017(E) Contents Page Foreword ..iv 1 Scope .1 2 Normative references ..1 3 Terms and definitions 4 Technical introduction ..1 4.1 Preliminaries .1 4.2 What is free form? 4.3 Does free form equal better vision? .2 4.4 Classification 2 5 Manufacturing 5.1 General 3 5.2 Conventional surfacing 5.3 Free form surfacing.. ..5 5.4 Comparison of conventional and free form manufacturing .6 6 Potential benefits of free form lens calculation. Oblique astigmatism . :> 6.1 1 6.2 Limitations of conventional lenses .9 6.3 Potential benefit of free form lens design. .10 6.4 Optimization for prescription. .11 6.5 Customization for the as-worn position. 6.5.1 Explaining the as-worn position .12 6.5.2 As-worn position and verification power ..13 6.6 Customization for the frame size .14 6.7 Personalization of the lens design 15 7 Measurement and quality control ..16 7.1 Lens performance. .16 7.2 Conformity with standards .16 7.3 Design integrity and process control ..17 7.3.1 General ..17 7.3.2 Surface shape measurement ..17 7.3.3 Through power measurement .17 7.4 Measuring the as-worn position 18 7.5 Inspection gates of the manufacturing process. 21 AnnexA(informative)Typicaldispensingflowchart .22 Annex B (informative) Measurement technology .23 Annex C (informative) Glossary of terms and their descriptions ..28 Bibliography. ..30 iii censee=ZHEJIANG INST OF STANDARDIZATION C1 5956617 vided by IHS under lic se with ISt ed withoutlicense from IHS Not for Resale, 2017/8/21 02:10:59