Sunlight entering a head-up display can travel backward through the projection optics and concentrate on the display panel, bezel, or nearby plastic. The vulnerable location changes with sun angle, so a single on-axis check can miss the path that matters.
HUD sun load analysis starts by locating those paths in the installed assembly. RayViz, Lambda Research Corporation's SOLIDWORKS Add-In, supports optical property assignment and ray-path visualization in CAD. TracePro provides the quantitative optical analysis needed to supply a thermal model with loading data.
Identify the surfaces that admit and concentrate sunlight
Include the windshield, dashboard opening, dust cover, mirrors, panel, and surrounding structure. A powered mirror can concentrate admitted sunlight, while apertures and covers determine which directions reach it. A bundle missing the active display may still strike a cable, frame, or housing feature.
Use the actual assembly positions and optical properties. The windshield and cover can redirect or attenuate incident sunlight, and a finish that appears dark in visible light may behave differently in the near infrared.
Apply properties deliberately to every relevant optical interaction. Avoid relying on unspecified CAD material behavior when tracing through a transparent part or evaluating a possible secondary reflection.
Screen the sun directions in SOLIDWORKS
Define an incident ray bundle that covers the relevant opening and represents a selected sun direction. Trace a set of elevations and azimuths appropriate to the vehicle orientation and test plan. Use a coarse angular survey to locate candidate paths, then refine around transitions and concentrated bundles.
Inspect where rays converge and which surfaces they strike. Record the sun direction, affected part, and path through the assembly. A sparse ray display is useful for understanding geometry, but ray density on screen is not a calibrated irradiance measurement.
Carry all relevant candidate cases into quantitative analysis. The most visually compact bundle is not necessarily the greatest absorbed load because transmission, spectrum, and material absorption also matter.
Test mechanical changes against both optical paths
Evaluate changes to the glare trap, aperture, baffles, shields, and nearby structure. Repeat the candidate sun directions after each revision to see whether the light is blocked, redirected, or concentrated on another component.
Check the intended display path through the required eye box at the same time. A baffle can intercept sunlight while clipping the projected image. Changing mirror position or tilt can also affect the display optics and needs review against the image requirements.
Follow reflected and transmitted paths beyond a proposed shield. A reflective surface can move the load to another part, while an absorbing shield needs a thermal path capable of carrying the deposited power away.
Quantify optical loading in TracePro
Save the prepared RayViz assembly in TracePro format for full optical analysis. Retain the source and property assignments, then verify them for the quantitative model. Use the irradiance, spectrum, angular distribution, and exposure conditions defined by the solar-load test or environmental requirement.
Represent the Sun's finite angular extent when calculating focused spot size and peak irradiance. A perfectly collimated screening source can produce an unrealistically narrow focus. Refine the sun-angle sampling and receiver resolution around candidate maxima, and increase ray count until the reported load is stable.
Report incident irradiance, spot position and extent, and absorbed optical power on the relevant parts. Use wavelength-dependent transmission, reflection, and absorption for the windshield, coatings, and receivers. A visible-light trace alone does not account for the full solar heat load.
If a concentration factor is reported, define its reference plane and whether it uses peak or area-averaged irradiance. Keep that definition consistent when comparing design revisions.
Connect the optical result to temperature
Provide the thermal team with the spatial distribution of absorbed power and the exposure conditions. Temperature depends on conduction, convection, radiation, heat capacity, and duration as well as the optical input. An irradiance map does not establish the panel temperature by itself.
Evaluate candidate infrared-rejection coatings using their measured or specified spectral and angular behavior. Track where the rejected energy goes, then recheck image transmission and the load on other parts. Correlate the combined optical and thermal prediction with the solar-load test.
Apply the workflow to other displays
The same progression applies to curved display covers, instrument clusters, and camera housings where sunlight can reach an optical element. Use RayViz to inspect the geometry, TracePro to quantify the optical loading, and thermal analysis to assess the resulting temperatures.
Request a RayViz demo to review sunlight paths in your SOLIDWORKS display assembly and plan the TracePro analysis before the solar-load test.