Patent ID: 6910786

Claim:
A lighting device for installation in a substantially plane surface comprising: at least one lamp unit that emits light essentially in specified light directions within specific angles of emission, which forms an angle with an axis at right angles to the substantially plane surface; a light refracting means in each of said at least one lamp unit, said light refracting means having a longitudinal direction coincident with said light direction, an incident face substantially at right angles to said light direction, and an exit face parallel to the substantially plane surface; said light refracting means is secured by a supporting means that extends along the whole length of the light refracting means; the light refracting means comprises a prism grating, consisting of discs of a glass material, preferably borosilicate glass, where between adjacent discs, and preferably on at least one of the side faces of the prism grating, there is provided a metal foil; and said angle is from about 41° to about 43°.