MenuChapter3Learn by Doing: Analyze a
Light Pipe
In this chapter, you open, view, ray trace, and modify a simple plastic light pipe. Then, you do some basic illumination analysis, introduce a scattering surface, and see the effect of this on the illumination distribution. This introduces you to many of the basic techniques needed to use LightTools.
SearchContents
What is a Light Pipe?..............................................................................................30Opening, Viewing, and Selecting............................................................................31Tracing Rays and Modifying the Light Pipe...........................................................35Performing an Illumination Analysis......................................................................43Optical Properties Example: Paint It White............................................................52Conclusions.............................................................................................................55
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CHAPTER3Learn by Doing: Analyze a Light Pipe
MenuWhat is a Light Pipe?
Light pipes are used in many applications where light must be guided from a source Searchto one or more illuminated areas. Light pipes in automobile dashboards can be very complex, and LightTools is a great tool for designing and analyzing such systems. You will start with a simple L-shaped plastic light pipe with a single flat surface to illuminate. This is similar to light pipes used to illuminate buttons or indicator lights in various devices.
When you are finished, the light pipe will look something like this:
In this chapter, you learn how to:?????
Open an existing LightTools model.Use 3D viewing selection tools.
Trace a fan of rays and modify the light pipe to redirect the rays to illuminate the target surface.
Use a pre-defined light source (simulating an LED) and a receiver (collection surface) to run a simple Monte Carlo illumination simulation.
Apply an optical property (Lambertian scattering) to a surface and rerun the illumination simulation.
Some of these features are briefly explained as they are introduced here, and
additional explanation is included in subsequent chapters. The main purpose of this chapter is to get familiar with the interface and with typical tasks and procedures.This is a very simple system, but it allows you to explore some of LightTools basic features.
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CHAPTER3Learn by Doing: Analyze a Light Pipe
MenuOpening, Viewing, and Selecting
The starting point for this light pipe model is supplied with the sample models in Searchthe LightTools installation directory. It is made of plastic (polycarbonate) and
consists of two blocks joined using Boolean operations, with a simple light source, and a rectangular dummy element (that is, an element that has no optical effect) with a receiver for illumination analysis. The source and receiver are on a hidden layer, so you won't see them at first.
Opening the Model
Note: Be sure that you have set your preferences as described in Chapter2.
1.Select File > Open on the menu bar.
If you didn’t close your model after you finished setting preferences, a
LightTools message is displayed warning that your model hasn’t been saved. Click Yes to close it now and continue.
2.On the Open dialog box, browse to the \\Tutorial folder of the LightTools installation directory, shown in the following figure.
3.Click the file name TD_Lpipe_start.1.lts and click the Open button.
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CHAPTER3Learn by Doing: Analyze a Light Pipe
MenuLightTools models are saved in files with the file extension .lts (for LightTools System).
SearchViewing the Model
The model opens, and the 3D Design view is displayed, showing four panes
(nominally, top, right, front, and isometric views, but you can change each pane as desired). Note that one of the panes has a red border around it, indicating that this is the active pane for any operations that depend on view-based coordinates. (In LightTools, you can use several different coordinate systems in various types of tasks.)
Now that a model is open, the navigation windows contain structured lists, which you will soon use to keep track of the parts of the system you are modeling and the various windows you will open. If you would like to explore the lists, click on plus signs (+) to expand hidden levels, and click on minus signs (-) to collapse a list.
1.Make sure the lower right pane is active (has a red border), then click the 1Pane button on the toolbar.The right side view now fills the entire display area, and the 4 Pane toolbar button is available to return to the 4-pane view when desired. Although you now see only a single view of the model, the right mouse button and the toolbar let you quickly change that view as needed.
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CHAPTER3Learn by Doing: Analyze a Light Pipe
Menu2.Use these view operations to set up a view similar to the following picture. To do this, you can:–Rotate the View. Place the cursor over the model, hold down the right mouse button, and slowly move the mouse around to spin the 3D Design view.–Zoom. Hold down the Control key and the right mouse button and move the mouse up or down. Move the mouse up to zoom in, or move the mouse down to zoom out.–Pan. Hold down the Shift key and the right mouse button and move the mouse to move the view around (pan up, down, left, right).
SearchNote: These view operations do not change any aspect of the model itself; you are simply “walking around” the model to view it from different virtual positions in space. Note that the coordinate axis rotates when you rotate the view. The objects in the model are fixed with respect to this global coordinate system. LightTools provides commands (such as Move) to change the position of selected object(s) within the model.
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