INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 4, ISSUE 04, APRIL 2015 ISSN 2277-8616 31 IJSTR©2015 www.ijstr.org Modification Of Normal Microscope To Magneto- Optical Microscope Nurazlin Ahmad, Azuraida Amat, Wan Yusmawati Wan Yusoff, Nurshahidah Osman, Noor Baayah Ibrahim Abstract: The present work reports on the modification of polarizing microscope to a magnetic domain imaging microscope based on Faraday Effect. Sample used in this research is a ferromagnetic garnet; (Bi,Tm,Na)3(Fe,Ga)5O12. The halogen lamp in the microscope is replaced by helium-neon (HeNe) laser as a light source. To reduce the laser spatial coherent effect, thin transparent plastics placed in the laser path. The plastics are rotated at certain velocity. Other factors to be considered are the plastic rotation velocity, the laser intensity and the laser alignment. Typical magnetic domain pattern is obtained with the new system. Index Terms: Magnetic domain, ferromagnetic garnet, HeNe laser. ———————————————————— 1 INTRODUCTION Magneto-Optical Faraday Effect Microscope is one of the important tools for observing the structure of magnetic domains of magnetic samples. According to Lee et al. [1], magneto-optical microscope provides shorter observing time and easier experimental methodology compared to other techniques. Other techniques can be performed on magnetic materials to study and measure the magnetic domain structure such as magneto-optical imaging, Bitter pattern imaging, transmission electron microscopy (TEM), electron reflection and scattering methods, mechanical microscanning techniques, etc. [2]. Tremendous studies about synthetic rare- earth iron garnets have been reported as they are widely used in microwaves and magneto-optical devices. One common based magnetic materials used in most research for magneto- optical imaging is Yttrium Iron Garnet (YIG). A survey of the characteristic of the optical and magneto-optical properties of the representative ferrite materials YIG and iron borate (FeBO 3 ) have been presented [3] and showed that these compounds are good electrical insulators, optical transparency in the visible spectral range and large variety of magneto- optical phenomena due to the interaction of light with the spontaneous magnetization. According to Aichele et al. [4], YIG can only provide a small amount of Faraday rotation (about 0.08 °/cm) which is not sufficient for the development of integrated magneto-optical devices. Thus, the additions of rare-earth elements such as bismuth into iron garnet thin films could increase the Faraday rotation in the visible to infrared range [5, 6]. Sample used in this research is a transparent ferromagnetic Sample used in this research is a transparent ferromagnetic garnet; (Bi,Tm,Na) 3 (Fe,Ga) 5 O 12 . Previous report [7] has mentioned that the material has an area called ferromagnetic domains that is areas where the magnetic moments aligned. Magnetic domain structure of the ferromagnetic garnet (FMG) can be observed by Faraday or Kerr Effect using magneto- optical effect. Sherwood et al. [8] reports that several magnetic oxides (Li, Mg, Cd and Zn) with a thickness of about 0.002 inch were transparent in the red end of visible light when viewed under a microscope with transmitted light. Magnetic domain of transparent rare-earth iron garnets, YIG have been observed through polarized light microscope [9]. Magneto- optical observation in transmission; using the Faraday effect is applied in this research as ferromagnetic sample is transparent. Faraday Effect depends on the rotation axis of polarized light. This technique requires the polarizing microscope, equipped with image processing equipment. The basis of the magneto-optical imaging refers to the rotation plane of polarization of linearly polarized light from the reflection or transmission through the magnetic material. Normally, the transmission is based on the Faraday Effect while the reflection is based on the Kerr effect. In both cases, the contrast domain is dependent on the magnitude and direction of magnetization of the sample. Polarization microscope used in this study is limited to magnetic samples as it cannot observe magnetic domain. Therefore, the aim of this study is to modify the set-up of polarizing microscope to a magnetic domain imaging system. 2 EXPERIMENTAL The polarizing microscope apparatus used in this study is "Research Metallurgical Microscope", DMLM model. This polarization microscope is equipped with a charge-coupled device (CCD) camera and is supported by a software known as Vision Builder AI 2.0. The image of the magnetic domains can be viewed via computer and stored in a file using the software with the help of the CCD camera. However, this microscope is limited to magnetic materials because of their inability to observe the magnetic domain structure. Therefore, some changes on the source of light of polarization microscope need to be done. First, the light source is replaced to a more appropriate light source. Next, some plastic sheets are aligned to the new light sources and a new black box to store light source is designed and finally aligned in the polarization microscope. Fig. 1 shows the schematic diagrams of polarizing microscope before and after modification. The illustrations of the optical system give an overview of the _________________________  Nurazlin Ahmad E-mail: nurazlin@upnm.edu.my  (A. Nurazlin), azuraida@upnm.edu.my  (A. Azuraida), yusmawati@upnm.edu.my  (W.Y.W. Yusoff), didaonb@yahoo.com  (Osman, N.), baayah@ukm.edu.my  (Ibrahim, N.B.Y.)  Institutions: Universiti Pertahanan Nasional Malaysia and Universiti Kebangsaan Malaysia.