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Advanced Tutorial - LED Extruded Reflector


Advanced Tutorial – Designing a Medium Flood Beam with an LED Source
This tutorial demonstrates importing an LED with integrated optics, designing a reflector around it to create a medium flood beam, and using an anisotropic material. It is a good idea to complete the beginner tutorials before attempting this advanced tutorial, since many of the more basic functions and concepts are not explained in this tutorial.

Import the Lamp
LED’s with integrated optics are modeled in a more complex way in Photopia than traditional lamps. The added complexity allows Photopia to simulate exactly how light emits from the LED chip, and how that light interacts with the LED’s integrated optics, such as a hemispherical lens. Because these lamp models have extra elements, they must be imported as component files, which include the chip core as a lamp model along with refractive and reflective layers that make up the optics around the chip. See Type 3 Source Models in Appendix B of the User’s Guide for more information. 1. Start a new project and choose File > Save As to give it a name such as LED Medium Flood. 2. Choose File > Import Component and then browse for the LED component file named W42180.cmp, which is the Seoul P4. Insert the component at 0,0.

Build the Reflector
3. From a front view, choose Design > Aiming Based > 3D Symmetric Extruded Reflector. a. Press Enter to accept the default lamp center of 0,0. b. Click a start point close to the base of the LED’s dome lens. c. Enter -50 for the reflector extent, in degrees.

d. Enter 0 for the aiming of the first section, in degrees. e. Enter -40 for the aiming of the last section, in degrees. f. Enter 5 for the angle increment, in degrees.

g. Enter 12 for the extrusion length, in inches.

Advanced Tutorial – LED Medium Flood

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4. Use Draw > Polygon Surface to create a reflector end-cap. Click the points in a rectangle shape that encloses the reflector profile.

5. Under Settings > Layers, create a new layer for the end-caps called REFL-End-caps with a color such as cyan. Place the end-caps on the new layer by selecting them and using the property control. Note that we need to place the end-caps on a different layer than the main reflector in this case because we will be giving a different anisotropic material orientation to the different pieces, and to do so they must not be on the same layer. 6. Move (under the Modify menu) the end-cap to one end of the reflector by selecting it from the top view, and the moving it up 6”.

Advanced Tutorial – LED Medium Flood
7. Mirror (under the Modify menu) the end-cap along a line from 0,0 to 1,0 to create the other endcap. 8. Use Show Surface Orientation (right-click in CAD view, then choose View Style) and Orbit (rightclick in CAD view, then choose Dynamic Views) to make sure that the end-caps are oriented correctly. The layer color (blue or cyan) should be faced inward, towards the LED.

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Setup the Materials and Output
9. Choose Edit > Design Properties to assign the materials. Assign Alanod 722 GP (a) to REFLMain and REFL-End-caps. Note that you will also see some layers that already have materials assigned to them. These are the LED layers that were imported with the component and they are already setup correctly for the LED.

Advanced Tutorial – LED Medium Flood

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Since we chose an anisotropic material (designated by the “(a)”), we need to orient the anisotropic material on the reflector. Assume that the grain goes along the direction of the extrusion. 10. Orbit in the CAD view to get a better view of the reflector. Use Wireframe view (right-click in CAD view, then choose View Style).

11. Select the reflector and choose Modify > Orient Anisotropic Material. 12. In the property control at the right of the screen, choose a Mapping Type of Project Along Y from XY Plane. Notice the arrows on the reflector; you may have to zoom in to see them. They are now in the correct orientation, along the direction of the extrusion.

Advanced Tutorial – LED Medium Flood

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13. Select both of the end-caps and choose Modify > Orient Anisotropic Material. 14. Choose the mapping type, Project Along X from XY Plane, and then zoom in on the end-caps to confirm that the material orientation is appropriate.

15. Choose Analysis > Photometric Output Specification and go to the Photometric Report tab. Change the Horizontal angles to 0(10)90. Keep the Vertical angles at their default of 0(5)90. Then change the Photometric Center Z coordinate to -0.24 and the Luminous Z Dimension to 0.

16. Under the Illuminance tab, create an illuminance plane 40’x100’, 8’ below the luminaire. Use Column and Row Spacings of 0.5 feet (under Calculation Points).

Advanced Tutorial – LED Medium Flood

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The default Raytrace Settings are appropriate for now, so we won’t adjust them at this point.

Design Results
17. Start the analysis by choosing Analysis > Begin Analysis. 18. Open the Photometric Report by choosing View > Photometric Report. Towards the bottom of the report is the Full Beam Angle, which is just over 80 degrees. This is a good medium flood beam size. 19. View other output such as the Shaded Illuminance Plot and the Polar Candela Plot (under the View menu). Overall, the design looks good.

Advanced Tutorial – LED Medium Flood

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Array the LED
Using a single LED to create a design like this one can be a very good representation of the final product which may have multiple LED’s. You can even change the lumen value under Edit > Design Properties so that the correct values of lumens, candelas, and footcandles/lux are displayed in your output for a multiple-LED luminaire. However, the longitudinal output (along the length that the LED is to be arrayed) may be slightly inaccurate in output such as the illuminance plots. For example, you may wish to confirm the accuracy of the Shaded Illuminance Plot along its length when using a row of arrayed LED’s rather than a single LED representation. Now that we have a design that we like, we can run a Photopia analysis with multiple LED’s. This run will be slower, but we already know that we like the current reflector design, and so a multiple LED analysis can be run with confidence that we will not have to go through several design iterations. 20. Save the current project, under File > Save. 21. Then choose File > Save As to save the project as LED Medium Flood – 1’ Array.ray. 22. Go to a top view in the CAD view and select the LED. 23. Choose Modify > Array. a. Press Enter to accept the default array type, Rectangular. b. Enter 11 for the number of rows. c. Press Enter to accept the default number of columns, 1.

d. Enter 1 for the distance between rows, in inches. 24. You should see the new array of LED’s. To give the array the correct location, select it by clicking on one of the LED’s, then enter -5 in the Origin Y value under Array in the property control.

25. Under Analysis > Raytrace Settings, change the number of Initial Source Rays to 25,000,000 by adding a zero. Note that the number of rays are divided between the number of sources. Since we have arrayed the LED’s, we need to increase the number of rays in order to maintain the same accuracy as the previous analysis. 26. Start the analysis.

Advanced Tutorial – LED Medium Flood
27. We would expect that output such as the Polar Candela Plot and Full Beam Angle be the same as that of the single-LED representation, and in fact it is. Viewing the Shaded Illuminance Plot, this plot also looks the same as in the previous run, and so it appears that even the longitudinal output was accurately represented by a single LED as well. In this case, the illuminance plane is far enough away that the single-LED representation would have been sufficient to represent a 1’ array length, but it is a good idea to confirm this.

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