Lenses and Louvers - Beam Control

Lenses and Louvers are simple devices you can use in your landscape lighting fixtures that allow you to change the beam of light to either soften or sharpen the glow as well as reshape the light. Different types of lenses provide different optics and there are four main parameters that you can manipulate. They are :

1. Beam spread

2. Beam edge definition/diffusion

3. Overall beam diffusion

4. Brightness


Rendering of a 35W, 36 degree lamp - mounted 18" from a wall, tilted to a 3 degree angle.

Optical Frosted Spread Lens

This glass lens is etched to create an even diffusion. Its effect is similar to the Optical Spread Lense but the diffusion effect is more pronounced, creating a wider beam with very diffuse edges and nearly obscuring the beam's hot spot. It reduces the center beam brightness by about 46%. This lens can be used whenever a highly diffuse light source is needed, especially useful when lighting certain plant material or statuary where hot spots would be problematic.

Addition of an Optical Frosted Spread Lens. Note that extreme diffusion towards beam edges makes edges less visible.

Optical Spread Lens

This glass lens sports ridges in a cross-hatched pattern. It's effect is called prismatic diffusion. It widens the beam slightly, softens the edges and softens the hot spot at the center of the beam. It cuts center beam brightness by about 20%. It's typically used when lighting walls or plant material when a softer, less defined beam is desired.

Addition of an Optical Spread Lens. Note that beam is wider, edges are slightly more soft.

Honeycomb Louvers

Black anodized aluminum louvers are composed of a honeycomb pattern of dividers. It cuts out stray light (glare) past about 45ß from the beam center. It also hardens the beam edge slightly and accentuates the hot spot. It decreases center beam brightness by about 30%. It's main use is in controlling glare. Typical scenarios would be to shield glare from fixtures in plant beds that are near walkways or driveways; or in cases where light might otherwise spill into windows.

Addition of Honeycomb Louver. Note that beam spread is very similar to 'no lens' but edges are sharper.

Optical Linear Spread Lens

This glass lens sports linear ridges. Its effects are the same as the Optical Spread Lens with the exception that it significantly narrows the beam in one direction creating a narrow oval. It decreases center beam brightness by about 50%. This lens is used whenever a long narrow diffuse beam is desired. Typical uses are for uplighting trees or flagpoles, as a wall wash for low retaining walls and for lighting along paths or driveways.

Addition of an Optical Linear Spread Lens. Note extreme widening of beam and retention of fairly hard edges. Since the beam shape is oblong, the above rendering shows the widest part of the beam illuminating the wall.

As you can see, using different lenses and louvers can create drastically different effects, especially when lighting architectural features, walls, stones and other surfaces. Adding specific angles of beam spreads can let you tweak your results even more!