Patent ID: 7369220

Claim:
A measuring apparatus which applies light, emitted from a light source, to a sample contained in a container, and detects light emitted from the sample to measure physical or chemical properties of the sample, comprising: a measuring optical system which measures the sample; and a position detection optical system which detects a position of a bottom of the container, the measuring optical system comprising: the light source for measurement; a condensing lens which applies the light from the light source to the sample; and a measuring detector which detects the light emitted from the sample, the position detection optical system comprising: a light source for position detection; a collimate lens which converts light from the light source for position detection into parallel light; a shading unit which shades substantially a half of a cross section of a luminous flux from the light source for position detection converted into the parallel light; a guiding optical system which guides a remaining luminous flux passing through the shading unit as parallel light on a half surface of the condensing lens; an image-forming lens which forms an image of the light applied via the condensing lens and reflected on a bottom of the container; first and second detectors for position detection provided at a focal point position of the image-forming lens to receive the light of the image formed on the bottom of the container; a calculating unit which calculates an index corresponding to a distance between the condensing lens and the bottom of the container in accordance with output values from the first and second detectors for position detection; and a controller which controls the distance between the condensing lens and the bottom of the container to vary the index to a predetermined value.