Optical components for daylighting and other purposes

An optical component of the type comprising two optically transparent bodies each having two major faces one of which is interrupted by a plurality of cavities in the form of grooves defined by spaced apart opposing walls, adjacent cavities being separated from one another by cavity separators in the form of elongate ribs, said cavity separators being defined by side walls inclined to one another, the two optically transparent bodies being placed in face-to-face relation with one another with the cavity separators of each said optically transparent body penetrating into the cavities of the other body, wherein one side wall of each said cavity separator has two side wall portions inclined to one another and the other side wall of each said cavity separator of one said optically transparent body comes into contact with the corresponding side wall of the other transparent body when said two optically transparent bodies are pressed fully together, such that said contact between said inclined surfaces of said bodies locks said bodies together in a predetermined position with respect to each other against movement in a direction parallel to the two major faces of said bodies and the voids formed by the facing said one side walls are defined by an elongate line where the opposite side walls meet.