Selecting The Correct Light Fixture Lens for Commercial Applications

Balancing the utilization of different types of light fixture lenses is essential to achieve both functionality and aesthetic appeal in lighting design. Understanding how light is dispersed and refracted through translucent material is at the core of using lenses to create a desired “type” of illumination.

The history of lenses can be traced back to ancient Egyptians, among others, who experimented with what we now know as optics. Isaac Newton’s Theory of Colour is based on his experiments with prisms and lenses. Italian priest, mathematician, and physicist Francesco Maria Grimaldi first used the term diffraction to refer to redirecting light in different directions. It seems the most common application for lenses among these ancient cultures was magnification. Still, as artificial light sources developed, lenses evolved into methods of controlling the distribution and spread of light.

The history of using lenses with light fixtures dates to the 18th century and has evolved significantly. In 1759, an optician from London proposed grinding lantern windows at the Eddystone lighthouse to form 15-foot diameter lenses, though this was impractical. The use of lenses in lighthouses began in England in the 18th century and was adopted in the United States by 1810.

In 1788, Thomas Rogers proposed grinding lighthouse lantern windows to form lenses, first implemented at the Portland Bill Lighthouse in England. In 1821, Augustin-Jean Fresnel developed the Fresnel lens, significantly improving lighthouse beacons by focusing light into a powerful beam. In 1852, John L. Gilliland of the Brooklyn Flint-Glass Company patented a method for making lenses from pressed and molded glass. This technology enabled the production of small bull’s-eye lenses used in railroads, steamboats, and docks. By the 1870s, these pressed glass lenses had become common in the United States, particularly for signal and safety lighting applications. The early 1900s saw the introduction of the Fresnel fixture to theatre and film lighting. This fixture allowed for a very smooth blend of light, which was particularly useful in these settings.

The evolution of lenses used today in light fixtures has been driven by the needs of specific industries, particularly entertainment and industrial lighting, focusing on improving light control, efficiency, and versatility in various settings. Adopting light-emitting diodes (LEDs) and continued technological growth in acrylic and polycarbonate materials has enabled the exceptional control over artificial light that we enjoy today.

Clear, diffused, or frosted. Understanding the similarities and differences.

The difference between clear and diffused light lies in how the light is emitted and spread, affecting the lighting’s intensity, direction, and overall appearance.

Clear light is emitted from a source with minimal diffusion, meaning the light beams travel directly and retain their full intensity and directionality. Clear light is bright, focused, and has well-defined edges. This type of light creates strong highlights and sharp shadows but can result in “hot spots” (areas of concentrated light).

Diffused light is softened and spread evenly through a diffuser, such as frosted glass, fabric, or a translucent plastic cover. Diffused light produces a softer, more even glow, reduces glare, minimizes shadows, and disperses across a broader area.

<H3> Are frosted and diffused lenses the same?

While frosted lenses are a type of diffused lens, not all diffused lenses are frosted. Both types aim to reduce glare and create more even light distribution, but frosted lenses specifically produce a soft, uniform gradient effect. The terms are often used interchangeably in casual contexts, but subtle differences exist in their light-spreading properties and manufacturing processes. Both soften the light, eliminate visual ‘hot spots,’ and create more comfortable illumination.

Frosted lenses are created through a sandblasting process to produce a “frosted” look that blurs the edges of the light beam. Frosted lenses also create a consistent gradient from the center to the edges and provide even light spread and softer illumination.

Diffused lenses are a broad category that includes frosted lenses. Diffusing can be can be achieved through various methods, not just sandblasting. All diffused lenses are generally designed to soften and spread light more evenly.

When to Use Clear vs. Diffused Light

Clear light may be the best choice in spaces where focused light is needed, such as above work desks or for accent lighting. Clear light may also be the best choice for modern, minimalistic designs where sharp contrasts are desired.

Diffused light may be the best choice in areas where comfort and even illumination are key, such as commercial spaces, medical rooms, or educational environments. Diffused light works well in fixtures designed for ambient or general lighting, such as troffers, surface-mounted wrapped LEDs, or high-bay luminaires.

Both clear and diffused lighting can be used in the same space to achieve the desired functionality and aesthetic appeal. When incorporating both diffused and clear light lenses in the same room, consider the following:

• Layer the light in ambient, task, and accent lighting for a dynamic effect.
• Use diffused light for overall illumination and clear light for specific focal points.
• Install dimmers to control the intensity of both clear and diffused lights, allowing you to adapt to the room’s mood.
• Match lighting temperatures to maintain a consistent color temperature (e.g., warm white or cool white) between clear and diffused lights to avoid clashes in ambiance.
• Avoid glare by positioning clear lights carefully to prevent direct glare or reflections, especially in areas with screens or reflective surfaces.

Visual comfort impacts from lens type

Clear and frosted lenses have distinct effects on visual comfort in a room. Clear lenses provide sharper, more focused illumination with a narrower beam angle, typically around 45° or less. Fixtures with clear lenses allow for higher brightness and efficiency due to minimal light obstruction, which may cause increased glare and harsher shadows. Sharp contrasts, more likely with clear lenses, can cause stress and fatigue as the human eye constantly adapts to different light levels. Generally, clear lenses are not desirable when visual comfort is a top priority.

Diffused lenses scatter and distribute light evenly throughout the space, using a wider beam angle, usually around 90°. Light diffusion reduces glare and harsh shadows, enhancing visual comfort with a softer, more uniform illumination. Diffused light is well-suited for creating ambient lighting and comfortable environments. However, the diffusion slightly reduces lumen output (typically 3-5% less than clear lenses).

When designing for visual comfort, it is essential to consider the specific needs of the space and balance factors such as light distribution, glare reduction, and appropriate contrast levels to create an environment that supports eye health and overall well-being.

Clarity and color impact of clear and diffused lenses

Frosted or diffused lenses help manage contrast levels in a room, which is crucial for visual comfort. However, diffused light tends to soften contrast, which may be a priority in medical, laboratory, food processing, and cleanroom applications. Both lens types can affect how colors appear in a room, which needs to be considered when selecting fixtures based on how the room is utilized. Clear lenses may provide more accurate color rendering, while frosted lenses can soften and diffuse colors slightly. High clarity and color rendering (CRI) is also dependent on other fixture specifications and not entirely on lens type.

Health benefits of diffused lenses

There are several health benefits to using frosted or diffused lenses over clear ones. Frosted lenses help distribute light more evenly, reducing glare and harsh shadows that can cause eye fatigue and strain. The diffused light from frosted lenses creates a softer, uniform illumination that is generally more comfortable for the eyes, especially in spaces requiring prolonged visual focus. Glare reduction is also significantly decreased with diffused, which is a significant factor in visual comfort and can help prevent eye strain and discomfort.

Prismatic, Polycarbonate, and Pebbles?

Lighting fixture lenses are also described using several other terms.

Prismatic lenses feature small refractive components that excel at light diffusion and glare reduction. These refractive components widen the light beam while softening edges, providing a more pronounced widening effect than other lens types. Among other applications, fixtures with prismatic lenses are suitable for areas with high ceilings, retail spaces, and commercial kitchens.

Solite lenses, also known as “small pebble” lenses, slightly soften beam edges while maintaining most of the light’s intensity, in contrast to some diffused and frosted lenses that reduce lumens by up to 5%.

Polycarbonate lenses are extremely durable and impact-resistant. Ideal for harsh environments or areas where safety is a concern, polycarbonate lenses are often used in vapor-tight fixtures for wet or dusty areas.

Discover a wide variety of lenses available for specification with KURTZON™

KURTZON™’s industry-leading specification grade troffers, downlights, round domes, and wrap luminaires offer a variety of lens types to meet your lighting needs. Learn more here.