Tunable White Optical Design Software | Photopia Optical Design Software

Tunable White & Color Mixing Optics

Photopia is the perfect optical design software for your tunable white, circadian lighting or RGBW mixing optical design projects. Photopia includes a large range of accurate white and RGB LED source models based on their physical geometry and measured spectral properties. Photopia also produces all standard photometric reports & plots for indoor, roadway and floodlight applications. Furthermore, Photopia’s true color images, color reports & special colorimetric plots help you both qualitatively & quantitatively evaluate the color uniformity in your beam. This is helpful when using single color white LEDs due to their variable spectrums over emission angle and emission area. It’s even more essential in tunable white applications with 2 or more different CCT LEDs used in the same optic.

mixed beam showing color uniformity

This example tunable white lens optic uses an array of 14 LEDs, half at 2700K and half at 5000K. The LED array is arranged to mix the colors as best as possible, but there are still large gaps between the LEDs of each color. Putting a simple diffuser in front of this LED array would mix the colors well, but that also eliminates your ability to control the beam shape. Many designs require specific intensity distributions such as a wide batwing, asymmetric wall washer or narrower spots & floods. This example achieves a 40° medium flood beam angle. Producing a controlled beam angle with well mixed colors requires adding beam spreading features to the optic that blend just the right amount, but no more. The types of curved facets shown on this lens are an effective mechanism for controlled beam spread. These types of features can be quickly generated for reflector and lens optics with the Grasshopper tool provided in one of our Rhino tutorials.

The images below show a design on the left that has less than ideal color mixing. The improved design on the right shows good color mixing. The first true color images show the appearance of the spot as best as possible, but these can only be judged qualitatively. If you look closely around the beam perimeter in the left image, you will see alternating regions that are more blue and more yellow. As the design gets closer to producing well mixed results however, it becomes more difficult to see the subtle changes in the true color image, which in part depends on the quality of your display. The additional plots showing quantitative color differences make it very clear when color deviations still exist, while also showing the magnitude of those deviations. This allows you to determine if your beam meets quantitative requirements, such as a +/-200K variation in CCT across the main spot or within some acceptable number of MacAdam ellipses.

The plots showing data in the u’v’ “uniform” color space are useful knowing that 0.001 in this space is 1 MacAdam Ellipse, which is a just perceptible color difference. Keeping max color differences to 0.004 within the main beam angle is a common goal for single color designs. This is much more difficult to achieve in a tunable white design, which therefore puts a greater emphasis on reducing the chance of perceiving distinct blue/yellow patterns in the beam.

mixed beam showing color uniformity