Patent ID: 7593615

Claim:
An optical device for guiding illumination comprising: a body with a surface having a plurality of acutely angled ramp structures; and each of said ramp structures having a front exit face for distributing said light, in which light when inputted at one end of said device is substantially totally internally reflected within said body until substantially distributed from the front exit face of each of said ramp structures, wherein said body has a first end representing said one end for inputting light, and a second end, and said ramp structures extend along a dimension between said first end and said second end representing the axis of the device, in which said ramp structures each have a ramp surface at an acute angle with respect to said axis, and the front exit face of each of said ramp structures represents a surface at an acute angle with respect to the normal of said axis, and wherein: Θ R represents the angle of the ramp surface with respect to said axis; Θ EF represents the angle of said front exit face of each of said structures with respect to the normal of said axis; said body is of material having a refractive index (NA); R n is a ratio of the refractive index of the material of said body to a refractive index of the medium surrounding said body; and said angles Θ R and Θ EF are selected in accordance with at least equations: Θ EF ≤ arc ⁢ ⁢ sin ⁡ [ 1 R n ] - arc ⁢ ⁢ sin ⁡ [ 1 R n ⁢ NA ] arc ⁢ ⁢ sin ⁡ [ R n * sin ⁡ ( Θ EF ) ] - Θ EF ≥ Θ R .