Patent SG-11201809394Y-A (SG)
Title: Apparatus and method for kerr imaging
Inventor: GAN WEILIANG
IPC: G01R33/032
Filed: 2017-05-08
Abstract: INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (19) World Intellectual Property :::` , 111111111111111111111111111111111111111111111111111111111111H110111111111110111111 Organization International Bureau (10) International Publication Number 03 (43) International Publication Date .....•\"\" WO 2017/196258 Al 16 November 2017 (16.11.2017) WIPO I PCT (51) (21) (22) (25) Filing Language: (26) (30) (71) (72) (74) (81) International Patent Classification: CA, CH, CL, CN, CO, CR, CU, CZ, DE, DJ, DK, DM, DO, GO1N 21/21 (2006.01) G01R 33/032 (2006.01) DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT, HN, International Application Number: HR, HU, ID, IL, IN, IR, IS, JP, KE, KG, KH, KN, KP, KR, PCT/SG2017/050237 KW, KZ, LA, LC, LK, LR, LS, LU, LY, MA, MD, ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI, NO, NZ, OM, International Filing Date: PA, PE, PG, PH, PL, PT, QA, RO, RS, RU, RW, SA, SC, 08 May 2017 (08.05.2017) SD, SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN, TR, TT, TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW. English Publication Language: English (84) Designated States (unless otherwise indicated, for every kind of regional protection available): ARIPO (BW, GH, Priority Data: GM, KE, LR, LS, MW, MZ, NA, RW, SD, SL, ST, SZ, TZ, 10201603665S 09 May 2016 (09.05.2016) SG UG, ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, RU, TJ, TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK, Applicant: NANYANG TECHNOLOGICAL EE, ES, FL FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, LV, UNIVERSITY [SG/SG]; 50 Nanyang Avenue, Singapore MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK, SM, 639798 (SG). TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, GW, Inventors: GAN, Weiliang; c/o Nanyang Technological KM, ML, MR, NE, SN, TD, TG). University, 50 Nanyang Avenue, Singapore 639798 (SG). LEW, Wen Siang; c/o Nanyang Technological University, Declarations under Rule 4.17: 50 Nanyang Avenue, Singapore 639798 (SG). — of inventorship (Rule 4.17(iv)) Agent: LINDSAY, Jonas Daniel; Marks & Clerk Singa- Published: pore LLP, Tanjong Pagar, P 0 Box 636, Singapore 910816 — with international search report (Art. 21(3)) (SG). Designated States (unless otherwise indicated, for every kind of national protection available): AE, AG, AL, AM, AO, AT, AU, AZ, BA, BB, BG, BH, BN, BR, BW, BY, BZ, = = = = = 122 \ 124 \ 126„ „ 122 130 132, (54) Title: APPARATUS AND METHOD FOR KERR IMAGING 120 (57) : An apparatus and method for Kerr imaging is disclosed. The apparatus comprises a light source and a polariser operable to pro- vide polarised light for incidence on a magnetic sample. An analyser is provided to convert differences in polarisation of the polarised light, af- ter reflection from the magnetic sample, into differences in light inten- sity and a detector is provided to detect the differences in light intensity for display as a Kerr image. At least one non-planar lens is employed between the polariser and the analyser and at least one corrective lens is provided to reduce polarisation aberrations introduced by the at least one non-planar lens. The method relates to removing a false signal from a Kerr image of a magnetic sample by subtracting unpolarised light sig- nals from polarised light signals of interest. = — = - Obtaining a first image of the magnetic sample in a first state of excitation, using a narrowband polariser configured to polarise light of a predetermined wavelength = = Obtaining a second image of the magnetic sample in a second state of excitation, using the narrowband polariser, wherein the second state of excitation is different from the first state of excitation = = = = J, = Aligning the first image with the second image = Subtracting the first image from the second image at the predetermined wavelength to obtain a raw Kerr image 11 GC kr) N v; CIA 11 ---.... IN 11 0 N ,[. for Subt b ra ic eting the first image from the second image at a wavelength b thenarrowband polariser has an extinction ratio of at least two orders of magnitude lower than that for the predetermined wavelength to obtain a false image 1 Removing the false image from the raw Kerr image to obtain a Ken image with false signals removed Figure 4(a) C