Patent ID: 7187446

Claim:
A measuring apparatus utilizing the phenomenon of attenuation in total internal reflection comprising a sensor well unit having a plurality of one-dimensionally or two-dimensionally arranged sample wells, which are formed in a dielectric block to open in a flat upper surface of the dielectric block, and a thin film layer provided on the inner bottom surface of each sample well, a light beam projecting means which causes a plurality of light beams to enter the dielectric block in parallel to impinge upon the interfaces of the inner bottom surfaces of the one-dimensionally arranged sample wells out of the plurality of one-dimensionally or two-dimensionally arranged sample wells and the thin film layers thereon at various angles of incidence so that total internal reflection conditions are satisfied at each of the interfaces, and a photodetector means which is provided with a plurality of photodetector elements each positioned in correspondence to one of the interfaces to receive the light beam reflected at the interface, wherein the improvement comprises a longitudinal tilt measuring means which measures a longitudinal tilt of the interface from a predetermined reference position changing the angle of incidence of the light beam to the interface, and an operation means which obtains a corrected measured value corrected according to the longitudinal tilt measured by the longitudinal tilt measuring means.