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Table of Contents
A common automotive application is to design a headlamp using total internal reflection (TIR) lenses. The following presents on overview of the optical design workflow for a TIR headlamp consisting of a high beam and a low beam. Using the LucidShape MacroFocal design feature to create TIR lenses, we will show design options with TIR devices for high and low beam applications, integrating these designs into an existing vehicle model to provide a realistic impression.
The full design process is shown in the Tech Talk which you can watch on demand: /optical-solutions/support/training/designing-tir-headlamp.html
Light Sources
One of the important initial design decisions is selecting your light source. LucidShape requires a light source for the MacroFocal calculations. In our example, we chose OSLON? Compact PL LED fay files from OSRAM, which produce white light. However, to produce more rays than the ray file has (for a better photorealistic rendering later), it was replaced by a Lambertian light emitting surface that corresponds to the size of the original lamp. The correct position, orientation, and spectrum of the light source were checked using the Color Data Analysis tool in LucidShape.
TIR High Beam Design
High Beam Model
The high beam design is inspired by the OSRAM Ford F150 headlamp module. The structure is straightforward: a collimator optic parallelizes the light from a divergent emitting light source, and the light control takes place on the lens with several facets.
High Beam Module Design and Analysis
The high beam setup consists of three modules. The design employs a rectangular symmetric collimator and MacroFocal lens for effective light distribution. After numerous simulations and tests, the collimators and lenses were transferred directly into CAD software using the geometry transfer function to cut them precisely into the housing.
Visualizations include different perspectives such as Bird's Eye and Driver View perspectives and spectral and non-spectral simulations to validate the design. Furthermore, test tables were used to check the light pattern for legal regulations.
TIR Low Beam Model
Low Beam Model Design and Analysis
The TIR optic for low beam application was created using the LucidShape MacroFocal Reflector design feature and clear plastic as the material. The switching function allowed the center facet to be disabled to make positioning the light source as easy as possible. Key features include varying the spread angles of the facets to achieve the desired low beam pattern. Finally, the reflector was transferred to CAD to create a closed body to generate a TIR object.
For the low Beam analysis, different views, spectral and non-spectral simulations and a test table were also used to check whether the pattern meets the requirements.
Photorealistic Simulation
To provide a realistic visualization, we took advantage of the luminance camera in LucidShape to collect data for a photorealistic rendering.
Human Eye Vision Post-Processing
The final visualization included post-processing with the Human Eye Vision Image (HEVI) tool. Using presets, photorealistic images can be created very quickly. The glare effect, in this example the Vos glare model, creates an even more realistic impression.
Summary
Using a collimator and lens or solid reflector are just two methods of designing TIR optics for high and low beam applications. Visualization of the models was also discussed to provide a comprehensive understanding of the design process.
To learn more about the details of the specific parameters and options used in the design process, watch the full tech talk on-demand.
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3 min read
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Jul 22, 2024
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