(19)

(11)

EP 3 899 420 A1

(12)

(43) Date of publication: 27.10.2021 Bulletin 2021/43 (21) Application number: 19823930.3 (22) Date of filing: 29.11.2019

(51) International Patent Classification (IPC):  G01B 9/02(2006.01) G01M 11/00(2006.01) G01B 11/16(2006.01) G01N 21/95(2006.01) G01N 21/88(2006.01) G01B 11/24(2006.01) (52) Cooperative Patent Classification (CPC): G01B 2290/70; G01B 9/02003; G01N 2021/9511; G01M 11/0271; G01N 21/95; G01M 11/005; G01B 9/02007; G01B 11/2441; G01N 21/45; G01B 11/162; G01B 9/02038; G01B 9/02057 (86) International application number: PCT/GB2019/053395 (87) International publication number: WO 2020/128423 (25.06.2020 Gazette 2020/26)

(84) Designated Contracting States: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR Designated Extension States: BA ME Designated Validation States: KH MA MD TN (30) Priority: 17.12.2018 GB 201820515 (71) Applicant: Compass Optics Limited Menai Bridge Gwynedd LL59 5NG (GB)	(72) Inventor: MITCHELL, John Gwynedd LL59 5NG (GB) (74) Representative: Scintilla Intellectual Property Ltd  The Centrum Building 38 Queen Street Glasgow G1 3DX Glasgow G1 3DX (GB)