Lighting device to simulate natural light

The present invention relates in general terms to a lighting device to simulate natural lighting, thus capable of generating at least two light components with different angular distributions having different correlated colour temperature or CCT. In particular, the present invention is directed to a lighting device (10,10') to simulate natural lighting comprising: a first optical unit (20) comprising a primary light source (21) configured to emit primary light (22) in the visible spectrum, and dichroic separation optics (23) configured to intercept at least part of the primary light (22) generated by the primary light source (21) and emit, from a first emission surface (25), at least one first highly collimated light component (24a) having a propagation direction (A), generated starting from the primary light (22), and at least one diffuse light component (24b), the at least one first highly collimated light component (24a) and the at least one diffuse light component (24b) forming a light with chromatic components having different angular distributions (24), wherein the at least one first highly collimated light component (24a) has a first correlated colour temperature (CCT1), a total flux and a luminous intensity profile characterized by a first angular aperture (a) which is lower than 30° measured as half width at half maximum (HWHM) with reference to at least one half-plane section (X) of the dichroic separating optics (23) containing the propagation direction (A), and wherein the at least one diffuse light component (24b) has a second correlated colour temperature (CCT2) higher than the first correlated colour temperature (CCT1) and a non- zero luminous intensity profile even for angles greater than 2 times the first angular aperture (a); and a second optical unit (30) comprising secondary collimation optics (33) configured to intercept at least part of the light with chromatic components having different angular distributions (24) emitted by the first emission surface (25) and generate, starting from this light with chromatic components having different angular distributions (24), a weakly collimated light component (34b) having a luminous intensity profile, referred to the half-plane section (X), characterized by an average value, calculated with reference to an attenuation angular range comprised between an attenuation angle (ϒ) and 90°, which is less than the average value of the luminous intensity profile of the at least one diffuse light component (24b), calculated with respect to the same attenuation angular range, the attenuation angle (ϒ) being measured with respect to the propagation direction (A) and being equal to at least 2 times the first angular aperture (a) of the luminous intensity profile of the first highly collimated light component (24a) emitted by the first emission surface (25), and a second highly collimated light component (34a) having substantially the same total flux as the first highly collimated light component (24a) and a second luminous intensity profile angular aperture (α') which is equal or less than the first luminous intensity profile angular aperture (a) of the first highly collimated light component (24a) emitted by the first emission surface (25); wherein the weakly collimated light component (34b) and the second highly collimated light component (34a) form a collimated light (34) with chromatic components having different angular distributions emitted by the second optical unit (30).