LED lenses are typically for changing the light distribution of the LED for various lighting applications.
Optical Engineering & Analysis LLC
Microsoft has developed a wedge lens for improving the efficiency of a display light guide. This also has applications to 3D projection displays without glasses.
Intensity Distribution from TIR Optics
Intensity distribution of LED without lens
Intensity distribution after lens. Notice the light distribution is more uniform in intensity.
A domed fresnel lens allows for better performance over the acceptable angle. These types of lenses are used extensively as solar concentrators.
Collimating optics for LED typically require complex geometry to get efficiency flux transfer
TIR optic consists of an inner lens and outer reflector and designed to be manufactured as one solid optic.
Line focus created by domed cylindrical fresnel lens.
Domed Cylindrical Fresnel Lens
Domed Fresnel Lens
Light shaping LED lens
Optical Engineering and Analysis, LLC