Optical feedback system with improved accuracy

An illumination system comprising:

• a plurality of light emitters,
• a light-collimator for collimating light emitted by the light emitters,
• light propagation in the light-collimator being based on total internal reflection,
• at least one light sensor for optical feedback being placed outside the light-collimator,
• the light sensor being arranged to receive light emitted by the light emitters exclusively through reflection at a light-exit window of the illumination system,
• wherein a side wall of the light-collimator is provided with a protruding portion for guiding the light reflected at the light-exit window of the light-collimator towards the light sensor.

An illumination system comprising:

• a plurality of light emitters,
• a light-collimator for collimating light emitted by the light emitters,
• propagation in the light-collimator being based on total internal reflection,
• at least one light sensor for optical feedback being placed outside the light-collimator,
• the light sensor being arranged to receive light emitted by the light emitters exclusively through reflection at a light-exit window of the illumination system,
• wherein the illumination system comprises a holographic diffuser, the holographic diffuser being provided at the light-exit window of the light-collimator.

An illumination system comprising:

• a plurality of light emitters,
• a light-collimator for collimating light emitted by the light emitters,
• light propagation in the light-collimator being based on total internal reflection,
• at least one light sensor for optical feedback being placed outside the light-collimator,
• the light sensor being arranged to receive light emitted by the light emitters exclusively through reflection at a light-exit window of the illumination system,
• wherein the light-collimator is provided with a reflector, and
• wherein the reflector is facetted or is shaped substantially according to a compound parabolic concentrator.

An illumination system comprising:

• a plurality of light emitters,
• a light-collimator for collimating light emitted by the light emitters,
• light propagation in the light-collimator being based on total internal reflection,
• at least one light sensor for optical feedback being placed outside the light-collimator,
• the light sensor being arranged to receive light emitted by the light emitters exclusively through reflection at a light-exit window of the illumination system,
• wherein the light emitters comprise at least a first light-emitting diode of a first primary color and at least a second light-emitting diode of a second primary color, the first and the second primary colors being distinct from each other.