Optischer Sensor

An optical sensor (1) comprising an integrated optical arrangement has a waveguide (4) and at least one defraction grating (5) arranged in this waveguide. Light can launched into the waveguide via the defraction grating. In the reflection area of defraction grating, part of the light is dispersed through the waveguide at the beam angle for which the launch conditions and thus the defraction in the waveguide are fulfilled, so that, at this angle, a dark line (14) occurs whose position is evaluated. The test result is influenced by the effective refractive index. Said index is also dependent on the measuring substance (9). To avoid complex alignment arrangements for the launch light beam (12), a convergent launch light beam focussing facility (13) is provided, overlapping or containing the launch light beam fitting the defraction grating (15). Thus, the launch angle of the bundles of rays (13) is largely uncritical, whereby the advantage is that any shifts in position which may occur wil l have no negative influence on the test result (Fig. 1).