Circular polarization interferometry configuration was used to develop surface plasmon based instrument, which had two light beams with p- and s- polarization states individually within the common path. We used evanescent field to determine the concentration of the biological sample via varying incident angles enabled phase interrogation. The instrument named "OBMorph" includes a light source, an easy to use incident angle varying scheme based on a parabolic and a spherical mirrors, and prism coupled sample stages. To increase the metrology sensitivity, which depends on precisely control the angular resolution, a precision step-motor coupled with a parabolic mirror were used to control the incident angle accurately. By using fault tolerance algorithm, the imperfect adjustment of circular polarization interferometer was eliminated to obtain a perfect Lissajous curve needed for circular polarization interferometry. The instrument developed was shown to have resolution as high as 4.92×10-6 RIU. The effect that refractive index of ITO thin film changes with respect to externally applied voltage was also adopted by coating an ITO thin film onto biochips so as to shift the surface plasmon resonance angle for larger phase interrogation ranges. We successfully measured CRP and anti-CRP specific interaction in 0.75 μg/ml ~ 400 μg/ml ranges. In addition, the concentrations of tuberculosis inhibitor - DHFR and compound Mg2P4O7 that can interact with CYP450 were also quantified successfully. The OBMorph was shown to have potential applications in areas such as flat panel displays, optical coating, and drug delivery, to name a few.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.