Sunlight-based sun imitating illumination

A sunlight-based projector system for providing a direct light beam, the sunlight-based projector system comprising:

• a sunlight receiving unit with a collector system, a plurality of optical fibers, and a plurality of fiber output channels, wherein the collector system is configured for collecting natural outdoor light, and for coupling the collected light into the plurality of optical fibers, wherein each of the plurality of optical fibers comprises a fiber output end, and each fiber output channel comprises at least one fiber output end from which divergent fiber output light is emitted, and
• a sunlight forming unit with a plurality of optical collimator units arranged in a one- or a two-dimensional array,
• wherein:
• each optical collimator unit is associated with a respective fiber output channel to receive the respective fiber output light and comprises at least one optical collimator configured to reduce the angular distribution width of the received divergent fiber output light,
• output areas of the plurality of optical collimator units form essentially a continuously extending large light-emitting face of the sunlight forming unit for emitting an essentially collimated light beam;
• and
• neighboring optical collimator units are separated by an absorber structure made of light-absorbing material to ensure that essentially only light from the associated fiber output channel is emitted from an output area of the respective optical collimator unit.

A sunlight-based projector system for providing a direct light beam, the sunlight-based projector system comprising:

• a sunlight receiving unit with a collector system, a plurality of optical fibers, and a plurality of fiber output channels, wherein the collector system is configured for collecting natural outdoor light, and for coupling the collected light into the plurality of optical fibers, wherein each of the plurality of optical fibers comprises a fiber output end, and each fiber output channel comprises at least one fiber output end from which divergent fiber output light is emitted, and
• a sunlight forming unit with a plurality of optical collimator units arranged in a one- or a two-dimensional array,
• wherein:
• each optical collimator unit is associated with a respective fiber output channel to receive the respective fiber output light and comprises at least one optical collimator configured to reduce the angular distribution width of the received divergent fiber output light,
• output areas of the plurality of optical collimator units form essentially a continuously extending large light-emitting face of the sunlight forming unit for emitting an essentially collimated light beam;
• and
• the continuous light-emitting face comprises non-emitting transition areas between output areas of neighboring optical collimator units and the non-emitting transition areas cover at the most 60% of the continuous light-emitting face and/or an extent of a non-emitting transition area between output areas of neighboring optical collimator units is at the most 0.5 times the maximum lateral size of an output area.

An illumination system for generating a sun-like appearance within a sun-sky imitating illumination system, the illumination system comprising:

• a sunlight-based projector system configured to generate a direct light component based on a direct light beam, the sunlight-based projector system comprising:
• a sunlight receiving unit with a collector system, a plurality of optical fibers, and a plurality of fiber output channels, wherein the collector system is configured for collecting natural outdoor light, and for coupling the collected light into the plurality of optical fibers, wherein each of the plurality of optical fibers comprises a fiber output end, and each fiber output channel comprises at least one fiber output end from which divergent fiber output light is emitted, and
• a sunlight forming unit with a plurality of optical collimator units arranged in a one- or a two-dimensional array, each optical collimator unit being associated with a respective fiber output channel to receive the respective fiber output light and each optical collimator unit comprising at least one optical collimator configured to reduce the angular distribution width of the received divergent fiber output light, wherein output areas of the plurality of optical collimator units form essentially a continuously extending large light-emitting face of the sunlight forming unit for emitting an essentially collimated light beam;
• and
• a diffuse light generating unit configured to generate a diffuse light component emitted across the direct light beam,
• wherein at least one of:
• the diffuse light generating unit comprises a Rayleigh-like scattering unit extending across the direct light beam that is configured to scatter more efficiently shorter wavelength light than longer wavelength light such that a portion of the direct light beam is diffuse emitted with essentially a Lambertian luminous intensity distribution;
• the diffuse light generating unit extends across the collimated light beam provided by the projector system and emits diffuse light with a FWHM of at least 3, 5, or 10 times the FWHM of the light beam;
• and
• the diffuse light generating unit comprises a light guide panel and at least one supporting light source for coupling light into the light guide panel and at least one decoupling element that is configured to extract light uniformly out of the light guide panel.

A sunlight-based projector system for providing a direct light beam usable for generating a sun-like appearance within a large area light output side of a sunlight-based illumination system, the sunlight-based projector system comprising:

• a sunlight receiving unit with a collector system and a plurality of optical fibers, wherein the collector system is configured to collect natural outdoor light, and to couple the collected natural outdoor light having a broad wavelength spectrum of sunlight into each of the optical fibers in the plurality of optical fibers,
• an active light source unit configured to complement the collected natural outdoor light with artificially generated light,
• a sunlight forming unit with at least one optical collimator unit, wherein each optical collimator unit is associated with at least one optical fiber and receives collected natural outdoor light emitted from the plurality of optical fibers and having the broad wavelength spectrum of sunlight and artificially generated light, and provides, based on the natural light and the artificially generated light, a collimated light beam, and
• a chromaticity based control system comprising
• a chromaticity sensor configured to detect the chromaticity of the collected natural outdoor light and/or the emitted collimated light, and
• a control unit configured to control the active light source unit in response to the detected chromaticity.

A sunlight-based projector system for providing a direct light beam usable for generating a sun-like appearance within a large area light output side of a sunlight-based illumination system, the sunlight-based projector system comprising:

• a sunlight receiving unit with a collector system and a plurality of optical fibers, wherein the collector system is configured to collect natural outdoor light, and to couple the collected natural outdoor light into the plurality of optical fibers,
• an active light source unit configured to complement the collected natural outdoor light with artificially generated light, wherein the active light source unit comprises a sunlight balancing light source configured to couple artificially generated light into an optical fiber that then follows a common optical path with the collected natural outdoor light and/or into an optical collimator unit to follow a common optical path with the collected natural outdoor light,
• a sunlight forming unit with at least one optical collimator unit, wherein each optical collimator unit is associated with at least one optical fiber and receives collected natural outdoor light emitted from the plurality of optical fibers and artificially generated light, and provides, based on the natural light and the artificially generated light, a collimated light beam, and
• a chromaticity based control system comprising
• a chromaticity sensor configured to detect the chromaticity of the collected natural outdoor light and/or the emitted collimated light, and
• a control unit configured to control the active light source unit in response to the detected chromaticity.