A measuring apparatus, comprising at least a first light source and a second light source for transmitting light; at least one light receiver for receiving light at least of a first received wavelength and a second received wavelength; at least one dispersing element for bending and/or refracting light; wherein the light transmitted by the light sources strikes the dispersing element and is so turned by the dispersing element that it strikes the light receiver. The first light source is arranged at a first angle relative to the dispersing element and the second light source at a second angle relative to the dispersing element, wherein the second angle differs from the first angle. The first angle is so embodied that the wavelength of the light turned by the dispersing element corresponds to the first received wavelength, and wherein the second angle is so embodied that the wavelength of the light turned by the dispersing element corresponds to the second received wavelength.