Abstract: A method and an apparatus for guiding and collecting light which arises or is reflected from a sample to be measured is described. The method and apparatus are intended to optimize guiding and collecting the light primarily in fluorimetry, nephelometry, luminometry and the like. The foregoing is achieved by a method which fixes the sample in a first focus of a reflector chamber having an ellipsoidal or paraboidal reflector surface of at least a half ellipsoid of revolution or paraboloid of revolution, and uses beams leaving that material which are reflected by the reflection surface. An apparatus of the kind set forth above is characterized in that at least the material to be measured is surrounded by a reflection surface of at least 2 PI sterradians of ellipsoidal or paraboloidal shape. Detectable light signals are received by a photosensitive surface positioned between a second focus of the reflector chamber and the center of the body of revolution for the case of the ellipsoid.