Fourier transform refractometry using multichannel detection

A versatile refractometer that utilizes multichannel interferometry is developed. The refractive index of a homogeneous sample placed in one arm of the triangular common-path interferometer is computed from the induced shift in the position of the He-Ne probe wavelength. The interferogram is detected by a 2048-element CCD line sensor and Fourier transformed by using a dedicated 32-bit microprocessor. The resolution and accuracy of refractive-index measurements depend on the angle of incidence that the sample makes with the optical axis of the interferometer.