PROCESS AND DEVICE FOR MEASURING PROPAGATION CHARACTERISTIC

PURPOSE: To ensure suitability for the analysis of a substance on sensor surface, and measure the propagation characteristic of an optical surface wave (induced optical wave) at high sensitivity by providing a sensor, an optical waveguide laminar structure, a grating coupler, a measuring device, an optical image pickup system and a positional analysis detector. CONSTITUTION: A double diffraction grating coupler 3 is provided at a planar waveguide 1 on a substrate 2. Reference waves 6 at a part of induced light waves 5 are shaded from a sample due to a covered layer 4, and arrive at sensor surface. Also, measurement object waves 7 as other parts of the light waves 5 interact with molecules to be detected on waveguide surface 8. The measurement object waves 7 and the reference waves 6 are then released, due to the existence of the coupler 3. Furthermore, a released wave zone is imaged on a position analysis detector 10 through a cylindrical lens 9, thereby providing spatial periodic interference pattern 11. Then, the spatial periodicity of the pattern 11 is evaluated through a Fourier transformation process relating to intensity distribution measured on the detection surface, thereby measuring the position-dependent relative phases of the object waves 7 and reference waves 6 very accurately. As a result, an analysis amount to be measured can be assigned.