Consider a handheld instrument that uses a purchased total internal reflection collimator over a mid power LED. The vendor datasheet states a 12 degree full width half maximum beam and 88 percent efficiency, the part is in stock, and the mechanical team drops the supplied STEP file into the assembly and moves on. First articles come back with a projected spot roughly 19 degrees wide and a visible bright ring around the edge. Nothing is defective. The datasheet figure was measured with a different emitter, on a different mounting datum, with the optic seated 0.4 mm closer to the die than the mechanical design allows once the board standoff and the solder paste stack are accounted for. The optic performs exactly as specified, in a configuration this product does not have.
A purely mechanical qualification of purchased optics starts with the drawing package, which verifies that the part fits and says nothing about whether it works in the assembly it is being fitted into. This article covers how to use RayViz inside SOLIDWORKS to trace a supplier component in its actual mounted position, what a CAD-stage trace can and cannot answer, how to build a short incoming qualification check that runs on the models a vendor already sends you, and when the question needs to move to TracePro.
Component datasheets describe performance under a reference condition, and the reference condition is chosen by the supplier. Four differences between that condition and a real assembly account for most of the surprises. Emitter geometry is the first. A collimator characterized with a 1 mm square die will behave differently with a 2 mm die, because collimation quality scales with the ratio of source size to optic focal length. A larger emitter produces a proportionally wider beam through the same optic, and the datasheet number does not transfer. Axial spacing is the second. Most secondary optics are sensitive to the distance between the emitting surface and the optic entry, and tenths of a millimeter matter. The mechanical stack that sets this distance includes board thickness tolerance, component standoff, adhesive bond line, and any gasket compression, none of which appear in the optic drawing. Mounting datum and tilt are the third. An optic held by two snap features against a board rather than by a machined seat will sit with a small tilt, and the beam tilts with it, usually at a larger angle than the mechanical tilt because of the lever arm through the optic. Surrounding geometry is the fourth and is the one most often ignored entirely. A datasheet measurement is made with the optic in free space. In a product it sits in a cavity, next to a wall, behind a window, and above a board with reflective solder mask and shiny component packages. Light that misses the optic or leaks from its sides interacts with all of that.
RayViz runs inside SOLIDWORKS and applies optical properties to solid bodies in the assembly, defines sources, and traces rays through the geometry as it is modeled. The value is that no export, no rebuild, and no separate model is involved, so the geometry being traced is by construction the geometry the mechanical team is actually holding. That makes it well suited to a defined set of questions. Whether the optic is seated where the design intends, and what the beam does at the mounted spacing rather than at the reference spacing. Whether the mechanical envelope clips the beam. A mounting boss, a snap arm, a ribbon cable, or the edge of an exit window intersecting the cone shows up immediately as truncated ray paths. Whether light leaks along unintended paths. A collimator with a flange that touches an adjacent wall will couple light into that wall, and the path is visible in the traced geometry. Whether the beam points where the mechanical reference says it points, once the real mounting features are included. These are geometric questions with geometric answers, and they are exactly the questions that are cheap to fix while the assembly is still open in CAD and expensive to fix after tooling. Ray tracing method and its role across the design workflow are covered on the TracePro ray tracing hub at TracePro ray tracing hub.
The workflow below can be standardized for the mechanical engineering team that imports the supplier model, with the source assumptions and pass/fail criteria established by optical engineering.
Supplier STEP and Parasolid files are produced for mechanical fit and are frequently defeatured for optical purposes. Check three things before anything else. Confirm the optical surfaces are present as real surfaces rather than simplified. A total internal reflection collimator whose faceted side wall has been replaced with a smooth cone is a common simplification and will not trace correctly. Confirm the body is a closed solid. Optical property assignment requires a watertight volume, and imported surfaces that fail to knit will not trace as a refracting body. Confirm the model is at the correct scale and in the correct units. This sounds trivial and is a recurring source of wasted time, because a millimeter model interpreted as inches traces without error and produces nonsense. Where the supplied model is defeatured, request the optical model explicitly. Most optics vendors maintain one, and the request is routine.
Assign the actual optic material rather than a generic transparent property. Polycarbonate at 1.586, PMMA at 1.49, and optical silicone near 1.41 produce meaningfully different results through the same geometry, and the difference is largest in total internal reflection designs where the critical angle sets whether a facet works at all. Assign absorbing properties to the mechanical bodies that surround the optic. Leaving a bracket with a default property lets it act as a mirror and hides leakage. Build the source at the emitter position with the actual die dimensions and the actual angular emission. A Lambertian surface source at the correct size is adequate for the geometric questions in this workflow. Then trace at the nominal mounted spacing and at both ends of the mechanical tolerance band. Three traces are enough to show whether the design sits on a sensitive part of the curve.
A CAD-stage trace is read visually and structurally rather than numerically, and that is a strength for the questions being asked.
Rays that leave the optic and immediately strike an internal wall identify a clearance problem. Measure it in SOLIDWORKS and fix it by moving the wall, which is a five-minute change at this stage. Rays that enter the optic and exit through a side face identify a coupling problem, usually a flange or a locating feature in contact with something it should be isolated from. The fix is a relief or a thin absorbing gasket, and the trace shows how much of the aperture is involved. A cone that is visibly wider than expected at the mounted spacing identifies a source size or spacing mismatch, and comparing the three tolerance traces shows whether the sensitivity is severe enough to warrant a tighter stack or a different optic. Rays reaching a detector or sensor position by an unintended route identify a crosstalk path. In assemblies where an emitter and a receiver share a housing, this is the single most valuable thing a CAD-stage trace finds, because the fix is almost always a wall or a rib and almost always trivial before the housing is tooled.
None of these findings require a photometric number. They require knowing which surfaces are involved, which is what the traced geometry in the assembly shows directly.
RayViz is a CAD-stage tool and the boundary of what it should be asked to answer is worth stating clearly, because pushing past it produces results that look authoritative and are not. Move to TracePro when the deliverable is a quantitative distribution. Irradiance and illuminance maps, candela distributions, luminance maps, and photometric file export are TracePro analyses, and a project that needs to report a number against a specification needs them.
Move to TracePro when scatter must be quantified against a requirement. Textured surfaces, molded finishes, painted interiors, and contamination all need bidirectional scatter distribution function models with measured or parametric data, and stray light questions where the answer is a small fraction of total flux cannot be settled from ray path visualization. Move to TracePro when the question is statistical. Worst case tolerance traces in CAD answer whether a limit can be exceeded. Estimating what fraction of production will fall outside a limit requires a randomized study across the tolerance distributions. Move to TracePro when the design needs optimization rather than verification. Reshaping a reflector or a light pipe extraction pattern to meet a uniformity target is a design task, not a check. The handoff is straightforward because RayViz shares its geometry and optical property assignments with TracePro, so the qualified assembly becomes the starting point for the deeper analysis rather than a model that has to be rebuilt.
The reason component surprises recur is that qualification is not part of the release checklist for purchased optics. Adding it costs very little. Require an optical model, not just a mechanical model, in the supplier data package. State it in the request for quotation so it arrives with the first samples. Record the mounted spacing, the emitter dimensions, and the surrounding geometry used in the trace alongside the vendor datasheet condition. When hardware disagrees with the datasheet later, the difference between the two conditions is already documented and the conversation with the supplier is short.
Run the three-point tolerance trace on each performance-critical purchased secondary optic, and flag any part where the beam width changes by more than a set threshold across the mechanical band. Those parts either need a tighter stack or a less sensitive alternative, and knowing which ones they are before design freeze is the whole point. Keep the qualified assembly file. Second sourcing a component later becomes a matter of swapping the body and retracing rather than restarting the evaluation.
A supplier optic that meets its datasheet can still miss the requirement in your product, because the datasheet describes a configuration the supplier chose and your assembly is a different one. Tracing the part in its real mounted position, with the real emitter size, the real mechanical stack, and the surrounding geometry present, catches the mismatch while it is still a CAD edit. RayViz makes that check practical for performance-critical purchased optics, and it keeps the model in the environment the mechanical team already works in. The cases that need quantitative distributions, scatter analysis, statistical tolerancing, or optimization then move into TracePro with the geometry and property assignments already in place.
Request a RayViz demonstration or a free trial to trace supplier optics inside your own SOLIDWORKS assembly and escalate the cases that need full photometric analysis to TracePro.