SS3 Pro Fog Lamp Case Study: Optical Performance and Beam Behavior

Introduction

Diode Dynamics recently introduced the  SS3 Pro, a high-output fog lamp that uses a TIR-collimator optic design. Its peak intensity approaches 12,000 candela, which sits close to the legal upper limit of 14,400 cd for fog lamps. In addition, the beam spans roughly ±45° horizontally and ±6° vertically.

After observing the lamp in person, I recreated its optical model for simulation-based analysis. That process revealed several insights into beam behavior and real-world performance. Below is a simplified breakdown of those findings.

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Understanding TIR Optics

TIR (Total Internal Reflection) optics use high-refractive materials such as PMMA or polycarbonate. Instead of relying on a mirrored reflector, they use the boundary between air and lens material to redirect light.

Traditional reflector optics work differently. They bounce light off a reflective surface shaped like a parabola. While effective, reflectors can lose some forward-directed light that never hits the mirrored surface.

By contrast, TIR optics capture more of the LED’s output. They redirect that light through both reflection and refraction. As a result, they typically achieve higher efficiency and stronger beam control for a given optic size.

However, TIR optics naturally produce a circular beam pattern. Designers must add secondary optical features to shape the beam horizontally or vertically.

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How the SS3 Pro Creates Its Beam

The SS3 Pro uses four TIR collimator optics paired with X-axis selective diffusers. These diffusers stretch the beam horizontally while maintaining a tight vertical spread.

Each unit uses Cree XP-L emitters, which provide strong intensity and compact output. According to measurements and simulations:

• Peak intensity exceeds 11,000 cd

• Main hotspot extends about ±40° horizontally

• Visible beam reaches roughly ±45°

The simulated beam matched real-world wall shots and measured data closely. That confirmed the accuracy of the optical model.

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Beam Quality Observations

During testing, one behavior stood out. The SS3 Pro produced a tall vertical gradient when installed at a default 0° aim. In simple terms, the beam sent significant light above the horizontal line.

On a wall shot, this glare can be difficult to see. The contrast between bright and dim areas tricks the eye into thinking the cutoff looks controlled. However, simulation revealed something different.

When measured against SAE J583 fog lamp standards, glare-zone readings exceeded allowable limits by 11.7 to 23.5 times in some areas. That result suggests the lamp must be aimed downward significantly to reduce glare.

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Aiming and Real-World Tradeoffs

To control glare within specification, the lamp required about -6° vertical adjustment. While this reduced upward light, it introduced another issue.

With that much downward aim, foreground illumination became extremely strong. In fact, the brightest point landed just 1.39 meters in front of the lamp. That area often falls outside the driver’s useful field of view. As a result, mid-distance visibility suffered.

Drivers therefore face a tradeoff:

• Leave the lamp at 0° and risk glare

• Aim downward and lose usable distance

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Why Wall Shots Can Be Misleading

Many users judge fog lamps by near-wall shots. Unfortunately, those images don’t tell the whole story.

Fog lamps usually mount lower than headlights. In a typical setup:

• Fog lamp height: 0.4 m

• Low beam height: 0.75 m

Because of this difference, fog-lamp glare may not appear above the low-beam cutoff until the vehicle sits more than 6–7 meters from a wall. At shorter distances, the low beam hides it.

This effect often creates the impression that glare doesn’t exist when, in reality, it becomes visible farther down the road.

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Practical Use Case

Despite these concerns, the SS3 Pro performs extremely well in certain roles.

At a 0° aim, it delivers excellent mid-distance illumination. That makes it a strong auxiliary driving or off-road lamp. In those scenarios, strict fog-beam cutoffs matter less.

However, when evaluated strictly as an SAE-compliant fog lamp, its vertical control falls short. The TIR-based design lacks independent control over the upper gradient. As a result, it struggles to maintain low glare while preserving distance.

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Limitations of TIR-Only Fog Optics

TIR optics excel at creating efficient, focused beams. Still, they typically produce symmetrical vertical gradients. Without additional vertical control features, designers cannot fully limit light above the horizontal axis.

Adding horizontal diffusers helps widen the beam. However, those diffusers do not address vertical glare. Because of this, TIR-only systems often work better as driving or auxiliary lamps than as dedicated fog lights.

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Conclusion

The SS3 Pro delivers impressive output and strong horizontal coverage. As an auxiliary or off-road light, it performs exceptionally well. Its intensity and beam reach provide excellent mid-distance visibility.

However, when used as a fog lamp, the design presents challenges. At default aim, glare rises above acceptable limits. When aimed downward to control glare, the beam shifts too much light into the immediate foreground.

In short, the SS3 Pro excels as a high-power auxiliary lamp. Yet its optical design makes true fog-beam compliance difficult without compromise.

In the next analysis, we’ll explore alternative optical approaches that better control vertical glare in fog-lamp applications

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