Secondary optical system design of LED in LightTools

Figure 1: LED secondary optical system

Generally, at the beginning of the design, we will draft a design framework, which will help us to clarify our design ideas and design goals. The following figure is the overall flow chart of our design:

Figure 2: Design ideas

designing process:

1. Import the real LED light source model, carefully check the model and clear the model reference coordinate position.

Figure 3: LED model

2. After the model check is completed, add the far-field receiver and surface receiver, and trace the appropriate light to simulate the light source. Observe the distribution of the system when the bare LED is used. This is the second step in the previous frame diagram: Analysis of the starting point. We can only determine what we should do next if we have a clear starting point.

Action: Add the surface receiver to the Z=20mm position; then right click on the view space and select the far field receiver; then turn on the two receiver properties and make sure the unit of measure is the luminous flux. Finally, return to the menu bar and select Ray Trace > Simulation Input... Trace 25,000 rays in the forward trace and display 100 rays, run the simulation, and click the “Begin Simulation” button.

Figure 4: Adding a far field receiver

Figure 5: Setting up two receivers as luminous flux units

Figure 6: Setting up the analog input

3. After tracking the light, we will start to analyze. View the illuminance simulation from the surface receiver separately; view the intensity simulation from the far field receiver. As can be seen from the intensity distribution map, the center of the LED light source is very weak and splits towards ±30°, and our design goal is 40% energy within ±5°, so we have to find a way to ±30° The light is concentrated to within ±5°.

Operation: In the Analysis menu, open Illuminance Display > LumViewer; in the Analysis menu, open Intensity Display > Slice Chart; right click in the system navigation or 3D view and select "Properties" to view the detailed parameters.

Figure 7: Surface Receiver and Far Field Receiver

Figure 8: Illumination distribution map

Figure 9: Intensity distribution map

Figure 10: Detailed parameters on the receiver

4. From the above simulation results, we have found that the “bat-like” distribution is not the distribution we want, then we have to find a way to change the LED light distribution using the principle of secondary optics. We intend to use total reflection or specular reflection to reduce the luminescence energy above ±30° and then use refraction to improve the luminescence energy less than ±30°. Reflection or total reflection can be achieved with a reflective bowl, refraction we can use a small lens to achieve, and then combine the two, this is our design ideas.

Operation: first create a lens, place the lens in the Z = 15mm position, and modify the lens shape to a quadric; create a SkinSolid entity (skin), place it in the Z = -0.5mm position, and set The SkinSolid solid material is PMMA; then a cylinder is created with the SkinSolid entity for Boolean operations, and a cylindrical space of approximately the size of the LED CoverLens is dug out from the SkinSolid entity; finally the lens and the SkinSolid entity are combined.

Figure 11: Two design methods

Figure 12: Design ideas

Figure 13: Combination

Figure 14: Creating a lens

Figure 15: Setting lens related parameters

Figure 16: Creating a SkinSolid Entity

Figure 17: Setting the SkinSolid Entity Parameters

Figure 18: Creating a cylinder

Figure 19: Calculating the cylindrical bore according to LED CoverLens

Figure 20: Setting the corresponding parameters of the cylinder

Figure 21: Boolean operations

Figure 22: Combining SkinSolid entities and lenses

5. Once the combined model is created, we can verify the effect of this combined lens, using NS non-sequential ray optimization lenses, which we covered in our previous article on optimization, which is not covered here.