抄録
A novel technique of optical spectroscopy based on a new concept is proposed. The principle is to used the dispersion of the Faraday rotation angle by transmitting a beam of light through a medium under a strong axial magnetic field, It is shown that if only the intensity of the component of the beam having one definite direction of polarization is detected, the signal can be expressed as the Fourier transform of the spectrum as a function of the Verdet constant. Thus the present method provides an entirely new and versatile spectroscopic technique which may be called as the Faraday Rotation Fourier Transform Spectroscopy (FRFTS). The resolution depends on the dispersion of the Verdet constant, which is known to be nearly inversely proportional to the square of the frequency, showing incomparably strong contrast to the modest dispersion of the index of refraction, especially in the short wavelength region. Another parameter which determines the resolution is the total number of polarization rotation, which may be limited by the limited available length of the medium due to the absorption of the light in the medium. A Faraday rotator developed in our laboratory is transparent in a wide wavelength range between the near infrared and the ultraviolet, and can be used in the present scheme only if the length were extended, which is of course possible without any technical break-through, indicating the possibility of ultra-high-resolution. Several typical examples are shown by computer simulation and the difference between the FRFTS and the conventional Fourier transform spectroscopy is discussed.
