ABSTRACT
New advances in polarized light microscopy have been employed to image Congo red stained amyloid plaques in sharp relief. The principle diagnostic criterion of amyloidosis, established by Divry and Florkin in 1927, is the detection with a polarizing optical microscope of so-called “apple green” birefringence from CR stained tissue sections. The chapter presents a newly developed imaging system to separate the optical transmission, refractive index anisotropy, and optical extinction that are otherwise convolved to produce the ill-defined apple green birefringence. The polarizing microscope, a prototype of the MetriPol System now available from Oxford Cryosystems, is adapted with a stepper motor driven rotating polarizer, circular analyzer consisting of a linear analyzer and quarter wave plate aligned at 45°, an 8-bit monochrome CCD digital camera, and a PC. The chapter shows that the system can be used to determine the absorption anisotropy and orientation of the electric dipole transition moment.
