Development of Polarization Sensitive Optical Coherence Tomography for Optoelectronic Material Characterization Ajay Vyas, Jitendra Solanki, † Pragati Patharia, Abhishek Garg, Pratima Sen † and Joseph Thomas Andrews Department of Applied Physics, Shri G S Institute of Technology & Science, Indore - 452 003 India. Email: jtandrews@sgsits.ac.in † Laser Bhawan, School of Physics, Devi Ahilya University, Khandwa Road, Indore - 452 007 India. Email: pratimasen@gmail.com Polarization sensitive optical coherence tomography system is developed for non-destructive test- ing and analysis of optoelectronic materials. The setup could obtain 2D (Surface) and 3D (surface and depth) images of the samples under study. In order to confirm the polarization sensitive mea- surements, we tested the optical birefringence properties of various samples. The setup developed has advantages such as compact, portable, cheaper and high resolution images (≈ 15m). I. INTRODUCTION Techniques such as X-ray computed tomography (CT) and magnetic resonance imaging (MRI) have revolution- ized diagnosis and treatment of illnesses. X-rays yield im- ages where bones are prominent since X-rays are far less absorbed by most other tissues in the body. MRI images examine the response of molecules to changes in mag- netic field and ultrasound images depend on the acoustic mismatches between adjacent tissues. Optical tomogra- phy is a new medical imaging technique that uses near infrared (NIR) light as the probing radiation [1]. Optical coherence tomography (OCT) is an emerging technique for producing high resolution (≈ few m) cross sectional images using low coherence interferometry in biological systems. OCT relies on the interferometric measure- ments of coherent backscattered variation to form im- ages of the subsurface microstructure & various biolog- ical tissues. Optical tomography offers the opportunity to identify the nature of a lesion without the need for compression of biopsy. Optical coherence tomography is a non-invasive and non-contact optical imaging modality technique perform- ing high resolution, cross-sectional images of the internal microstructure in materials and biological systems (tis- sues) by measuring backscattered or backreflected light. Conventional OCT is based on intensity measurements and provides structural information of tissue. Image res- olution of (≈ 1-15 m) can be achieved, one to two or- ders of magnitude higher than with conventional ultra- sound [2]. Imaging can be performed in situ and real time. Polarization sensitive Optical coherence tomog- raphy (PS-OCT) has advantages over conventinal OCT which extends the concept of OCT and uses the polariza- tion properties of light together with additional informa- tion on the birefringence properties of the sample. The information provided by polarization sensitive OCT im- ages can be used to identify birefringent structural con- stituents in the target tissue or sample that are otherwise in-visible to conventional OCT. Clearly, a noninvasive method of assessing burn depth would be beneficial to the patient and surgeon. Polarization-sensitive optical coherence tomography (PSOCT) is a recently developed imaging technique that can potentially assess burn depth in vivo. polarization sensitive OCT images of a tissue or sample can be related to a change in the structure and functionality or integrity of the target. The polarization effect in backscattered light can yield useful information about local changes of the material birefringence. A bulk PS-OCT system is developed using polarization beam splitter and beam splitter to measure birefringence prop- erties of samples. By analyzing the polarization state of light reflected from various depths in a sample, PS-OCT is able to provide information on the content and condi- tion of collagen and, therefore, the depth of thermal in- jury [3–5]. The major advantages PC-OCT are the high signal to noise ratio, capability to diagnose visualization and local birefringence, better resolution ≈ 4 m, high sensitivity and large dynamic range. PS-OCT takes into account the vectorial nature of light waves (state of polarization) [6]. The most complete information about the polarization properties of a bio- logical target is given by systems capable of producing depth resolved Mueller matrix elements. These configu- rations can account for depolarization as well as changes in the total, linear and circular degree of polarization of the probe beam during propagation in tissue. Polar- ization Sensitive-OCT is can be adopted to almost every area of biomedical engineering where imaging is a critical method for diagnosing [7]. PS-OCT requires additional complexities for the mea- surement and data processing due to the unpredictable birefringence of the material. We develop a PS-OCT us- ing bulk optical components. The setup could success- fully measure optical properties of optoelectronic materi- als as well as obtain cross-sectional images of the sample under study. II. EXPERIMENTAL SETUP The heart of the OCT system is a Superluminescent diode (SLD). Low coherence length of SLD suggests higher transverse resolution of images [11]. The Hama- matsu SLD used in our setup has a coherence length of (≈ 30 m). A Michelson interferometer with polarization