In industrial, commercial, and warehouse lighting design, precision and performance are paramount. A single component, a light refractor, can significantly influence the direction, intensity, and uniformity of light from a high bay luminaire. This guide explores what a refractor does and how its effects are captured in photometric studies.
Key Takeaways
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- Precise Light Control: Refractors are optics that control the light distribution from a luminaire. They shape the raw, wide output of an LED into a specific beam pattern (e.g., narrow, wide, or asymmetric) to improve efficiency and direct light where it is needed.
- Improved Glare Control and Comfort: By directing light downward and shielding high-angle brightness, a prismatic refractor can significantly improve visual comfort and lower glare ratings (UGR), a critical factor in occupant productivity and safety.
- Photometric Validation Required: Adding or changing a refractor creates an entirely new luminaire from a performance standpoint. Its impact must be analyzed through a professional photometric study to ensure design compliance and real-world performance.
Understanding Light Refractors
A light refractor is a transparent or translucent optical component, typically made of acrylic or polycarbonate, that reshapes how light exits a fixture. It operates through refraction, bending light as it passes through the material. In modern LED fixtures, its primary role is to take the very wide, inefficient light from the bare LED source and focus it into a more controlled and useful beam.
Types of Light Refractors
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Lenses (Prismatic & TIR Refractors): Provide precise control over light distribution. Total Internal Reflection (TIR) optics and prismatic lenses are designed to achieve a specific beam angle, focus light effectively, and maximize output for targeted illumination.
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Diffusers: Scatter light to obscure the lamp image and create a softer glow, prioritizing visual comfort and broad coverage over precise intensity.
Both types are used in high bay and low bay luminaires to achieve desired beam patterns and enhance lighting quality.
Impact of Refractors on High Bay Lighting
High bay fixtures, typically installed 25 feet or higher, are designed to deliver powerful, directed illumination for large indoor spaces such as factories, warehouses, and gymnasiums. The choice of refractor is critical to their performance.
Effects of Adding a Refractor
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Precise Beam Control: Contrary to the common belief that optics always widen the beam, they often serve to narrow it. A refractor can focus the light from a 120°+ bare LED source into a more useful 90°, 75°, or even narrower beam to increase intensity at floor level.
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The Glare vs. Uniformity Trade-off: There is often a direct trade-off between glare control and uniformity. A narrower beam (e.g., 75°) will typically provide superior glare control (lower UGR) but may create hot spots and require a denser fixture layout to achieve good uniformity. A wider beam (e.g., 90°) may improve uniformity but can produce more glare.
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Improved Vertical Illuminance: Specialized drop-lenses and refractors can be used to push more light onto vertical surfaces, which is particularly valuable for illuminating shelving and racks in warehouse aisles.
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The Critical Role of Mounting Height: Height is a decisive factor. A narrow beam optic that creates poor uniformity at 20 feet may perform perfectly at 30 feet, as the light has more distance to spread out. Higher mounting heights generally improve glare performance and allow for the effective use of more focused beams.
How Photometric Studies Reflect Refractor Changes
Photometric studies simulate lighting performance before installation. Adding a refractor fundamentally alters a luminaire’s light distribution, a change that can only be accurately predicted with an updated photometric file.
A Refractor Creates a New Luminaire. It is critical to understand that a luminaire with a refractor is a different fixture from one without it. The performance data is captured in a lab-tested data file (.IES or .LDT). That specific file must be used in the design software, as the candela distribution curve that defines the beam shape cannot be reliably estimated or modified without a new lab measurement.
Changes with a Refractor
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Altered Candela Values: The luminous intensity at every angle changes to reflect the new distribution.
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Altered Beam Angle: The beam angle is changed to be narrower or wider, resulting in a different pattern of light on the illuminated area.
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Shifted Light Output Pattern: The entire light spread is reshaped, affecting vertical and lateral distributions.
Impact on Lighting Metrics
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Illuminance Levels: Light is redistributed, changing the footcandle (fc) or lux values across the workplane. This may increase intensity under the fixture (with a narrow beam) or spread it to peripheral zones (with a wide beam).
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Uniformity Ratios: The choice of optic directly impacts uniformity (measured as max/min or avg/min). Design choices often involve balancing the desired uniformity with other goals, like glare control.
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Glare Potential: A diffusing refractor reduces surface luminance. More significantly, a prismatic refractor that narrows the beam can decrease perceived glare by directing light downward and reducing high-angle brightness, leading to better UGR values.
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Light Trespass and Compliance: A wider-beam refractor increases the risk of lateral light spread and potential trespass, requiring careful analysis in a photometric study to ensure compliance with local codes.
Why Run a Comparative Photometric Study?
To make an informed decision, a comparative photometric study is necessary to evaluate the impact of different refractor options. This analysis relies on the manufacturer’s official IES files for each configuration.
Benefits of Comparative Analysis
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Informed Decision-Making: A study allows for a clear comparison between different factory-provided refractor options (e.g., a 90° standard optic vs. a 75° glare-control optic) to visualize the trade-offs.
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Design Optimization:
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Visualizes the refractor’s true impact on the final beam patterns.
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Confirms that the proposed design will comply with lighting standards (e.g., IES RP-7 for industrial lighting).
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Informs final decisions on fixture placement, spacing, and mounting height before any equipment is purchased or installed.
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Conclusion: The Role of Refractors in Lighting Design
Adding a light refractor to a high bay luminaire does more than alter its appearance; it fundamentally transforms its photometric performance. By precisely controlling the light, refractors achieve critical lighting objectives, including targeted illumination, enhanced uniformity, and significantly reduced glare. However, these benefits introduce design variables that must be carefully measured and understood. Photometric studies, which utilize accurate lab-tested data for each specific fixture-optic combination, provide the essential insights needed to ensure designs meet standards, support safety, and deliver optimal performance.
Next Steps
Ready to explore high bay lighting with refractor options? Visit AccessFixtures.com to shop high bay light fixtures or contact our lighting specialists for expert guidance.
Light Refractor Frequently Asked Questions (FAQs)
What is a light refractor in high bay lighting?
A light refractor is a transparent or translucent component, typically acrylic or prismatic glass, that reshapes light output through refraction or internal reflection to control beam patterns.
How does a refractor differ from a reflector in high bay fixtures?
A refractor bends or scatters light as it exits the fixture, while a reflector redirects light before it leaves, using a mirrored or prismatic surface to shape the beam.
Why use a refractor in high bay lighting?
Refractors widen light distribution, improve vertical illuminance, reduce luminance for comfort, and allow wider fixture spacing, enhancing efficiency and performance.
What are the main types of refractors?
The two primary types are lenses (prismatic refractors) for precise light control and diffusers for scattering light to reduce glare and soften illumination.
Can refractors increase glare in high bay lighting?
Yes, wider light distribution from refractors may increase glare from certain angles, but photometric studies and careful design can help mitigate this risk.
How do photometric studies help when adding a refractor?
Photometric studies simulate lighting performance, using updated .IES or .LDT files to predict changes in illuminance, uniformity, glare, and compliance after adding a refractor.
What is the difference between high bay and low bay refractor applications?
Low bay fixtures (15–25 feet) see more pronounced effects from refractors due to lower mounting heights, while high bay applications (25+ feet) require photometric validation for effectiveness.
How does a refractor affect light trespass?
Refractors increase lateral light spread, which may cause light trespass beyond the intended area, necessitating photometric analysis to ensure compliance with regulations.
Why is uniformity important in high bay lighting?
Uniformity, measured as max/min or min/avg ratios, reduces contrast for better visibility, safety, and comfort, especially in large spaces like warehouses.
How can I evaluate a refractor’s impact before installation?
Run a comparative photometric study to analyze the fixture with and without the refractor, assessing beam patterns, uniformity, and compliance with standards like IES RP-7.
Are refractors compatible with both LED and HID high bay fixtures?
Yes, refractors can be used with both LED and HID high bay fixtures, though their design must be optimized for the specific light source to achieve the desired performance.
What standards should high bay lighting with refractors meet?
Fixtures should comply with IES standards (e.g., RP-7 for industrial lighting, RP-6 for sports facilities) and local codes, including dark sky or wildlife protection guidelines.
