Calendar
SPIE Photonics West
January 22-27, 2011
San Francisco, California
Booth 1200
SPIE website
Strategies in Light
February 22-24, 2011
Santa Clara, California
Booth 516
SIL website
Introduction to Illumination Design Using LightTools
April 11-14, 2011
Pasadena, California
More details
COM Macro Programming in LightTools
April 15, 2011
Pasadena, California
More details
SPIE Optifab
May 9-12, 2011
Rochester, NY
Booth 403
SPIE Optifab website
LIGHTFAIR 2011
May 15-19, 2011
Philadelphia, PA
Booth 3524
LIGHTFAIR website
For a complete list of LightTools events worldwide: visit our website
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In this issue:
New Version of LightTools Available
We are pleased to announce LightTools 7.1 FCS is now available for download at ORA’s Customer Support Portal. For users who receive updates via download, the release contact at your site has been sent email with information on obtaining license files for this update. If you have not received your LightTools 7.1 license file, please email us at support@opticalres.com. Be sure to include your LightTools USB dongle number when requesting your license file. For those who have requested DVDs, we are currently shipping these now.
LightTools 7.1 contains many useful enhancements. Some key new features include:
User interface improvements that allow users to maximize the design view and improve productivity. For example, charts can be placed on their own tabbed view and dialog boxes can be docked together and automatically minimized. View the video
Standard Photometric Reports
LightTools 7.1 contains a utility for automatically generating photometric reports in the standardized IES format. IES Indoor, Flood and Road Report types are all supported. View the video
Support for IES photometry types A, B, and C for orienting intensity data for both far-field and surface receivers. Users can specify IES photometry types on any receiver in the model to orient the intensity data. The intensity data and charts better correspond to the labels and bounds that are measured by goniophotometers. View the video
CIE color difference analysis
Users can compute and optimize color differences on any spatial or angular mesh. When they specify a color target, the Cartesian distance between the target and any point in the mesh is calculated. They can then optimize the color differences, and as the variations become smaller, the color becomes more uniform at the target. View the video
Additional information on these and other enhancements included in LightTools 7.1 can be found in the LightTools 7.1 Release Notes.
Quick Tip: Verifying Collimation with Intensity Encircled Energy
Many times when designing illumination systems, it is necessary to collimate light. When doing this, a good question to ask is: how good is my collimation? The LightTools feature that helps you determine your level of collimation is the intensity encircled energy. With the correct settings, the intensity encircled energy analysis will tell you what percentage of your light is contained within an angular cone of a particular size. If you have a high percentage of light distribution within a small cone angle, then you are reasonably well collimated. If you know the etendue of your source, you can use the same information to know how much better your collimation can be, theoretically.
To demonstrate the use of intensity encircled energy, consider the LED collimator shown below. The axis of the far-field receiver is aligned with the collimator’s optical axis.
To display the intensity encircled energy, choose the menu. This creates a new chart view showing the intensity encircled energy, as shown below.
To see the percent power as a function of cone angle, you need to make a few changes to the settings. Open the Properties dialog box for the far field receiver, and look at the properties for the forward encircled energy. The default settings are shown below.
Click to enlarge picture
Change the settings as follows:
- Number of Apertures set to 100 (the default of 10 displays the encircled energy in 10% increments)
- Sizing Based On set to Percent Power
- Select Fit Boundaries to Data
- Power Scaling set to Normalize
With the settings changed, the encircled energy chart looks like this.
On the results tab of the data table, you will see a list of the percentage of the energy contained in the corresponding cone’s half angle. For this system, 90% of the energy is contained within a half angle of 12.6 degrees.
As a final check, you can validate these results against the etendue limit. The source emits into a full sphere from a surface area of 1.4 mm2. It is immersed in a medium with a refractive index of approximately 1.5. With a collimator output radius of 10 mm emitting into air, the etendue relationship looks like the equation below.
If you solve for the half-angle alpha, you find that the etendue limit is roughly 5.75 degrees. In this example, about 72% of the energy is within this half angle. Not too shabby.
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