Abstract: An optical device for modifying a light distribution is made of transparent material and includes a front wall constituting a front portion, a coupling portion for connecting to a light source system, and side walls between the coupling portion and the front portion. The front wall is configured to let through a first part of light emitted by the light source, and the side walls are configured to let through a second part of the light. The side walls have grooves that refract at least 80% of the second part of the light obliquely rearwards with respect to a direction from the coupling portion to the front portion. Thus, the optical device can be used for illuminating both a floor and a ceiling so that light emitted to unwanted directions and potentially causing glare can be kept at a low level.

Abstract: A light guide element (201) for modifying a light distribution pattern of a light source (202) is presented. The light source radiates first light beams to a first quarter-space and second light beams to a second quarter-space, where the first and second quarter-spaces are defined by mutually perpendicular spatial planes and one of the spatial planes constitutes a planar boundary between the first and second quarter-spaces. The light guide element includes transparent material (207) on a route of the first light beams for modifying the light distribution pattern of the first light beams and a reflective surface (208) for reflecting at least a part of the second light beams to the first quarter-space. A surface of solid material on a route of the second light beams includes grooves for spreading the light distribution pattern of the second light beams in the direction of the section line between the spatial planes.