A method for operating an apparatus for detecting matter, the apparatus comprising:
- an irradiation arrangement, which comprises a first illumination device adapted to emit a first set of illumination beams and a second illumination device adapted to emit a second set of illumination beams, wherein each one of said first and second illumination devices is selected from a group comprising halogen illumination devices, Xenon arc illumination devices and LED illumination devices,
- a scanning element,
- an optical arrangement, adapted to receive and direct at least one of said first and second sets of illumination beams towards said scanning element,
- wherein the scanning element is configured to redirect said at least one of said first and second sets of illumination beams towards a first detection zone through which the matter is provided,
- a detector system including at least one sensor arrangement adapted to receive and analyse optical radiation which optical radiation is reflected, emitted and/or scattered by matter in the first detection zone, in response to said matter being irradiated by at least one of said first and second set of illumination beams,
- a reference arrangement comprising a white reference element, which reference arrangement is adapted to receive optical radiation from at least one of said first illumination device and said second illumination device and to direct said received optical radiation towards said detector system via said white reference element, which reference arrangement is arranged up stream of said scanning element comprising the steps of:
- arranging said first illumination device in an active illumination position and said second illumination device in an in-active illumination position, emitting a first set of illumination beams from said first illumination device towards said first scanning element,
- based on the condition of said first illumination device and/or in response to a user-initiated input initiating an automated or semiautomated switching event wherein said first illumination device is moved to an in-active illumination position and said second illumination device is moved to said active illumination position, wherein said first and second illumination devices are moved simultaneously to the respective one of an in-active illumination position and an active illumination position,
- wherein said irradiation arrangement is configured to emit an illumination beam only from the one of said first and second illumination devices arranged in said active illumination position, and wherein said in-active illumination position is configured to allow for exchanging of one of said first and second illumination devices during operation of an other of said first and second illumination devices in the active illumination position, preventing an actuator from moving said first and second illumination devices within one or more pairs of guiding rails beyond a first and/or a second position, by means of at least one positioning element.