Freeform glass
Refracts through a directly editable boundary of straight segments and exact circular arcs. Supports constant index or selectable catalogue-glass dispersion and traced GDD; overlapping glass bodies are not surface-merged.
Open in the canvas →In the real world
Real glass optics are rarely limited to a lens's spherical curve or a prism's flat triangular faces — aspheric correctors, light pipes, freeform illumination optics, and hand-ground custom prisms all refract light through an arbitrary boundary shape. However exotic the outline, the physics at every point on the surface is the same vector Snell's law that governs a plain prism or lens face; only the local surface normal changes from point to point.
This is also literally how any CAD or ray-tracing renderer handles a smoothly curved optical surface in practice: an arbitrarily smooth boundary is approximated as a fine mesh of flat facets (or, for a closer fit, circular arcs), each refracting independently, with the approximation error shrinking as the facets get smaller. A coarse hand-built approximation and a smooth manufactured asphere differ only in how fine that mesh is.
In OpticalSetup
The boundary is drawn as a chain of straight edges and true circular arcs — editable directly on the canvas by dragging anchor and curve-control points — and each segment becomes its own independent refracting surface, so a completely custom cross-section (a light pipe's tapered profile, a freeform prism, a corrective wedge) refracts and totally-internally-reflects exactly like the fixed-geometry Prism, just without being locked to a triangle. Choose a constant refractive index or one of four catalogue models: N-BK7, fused silica, N-SF5, and N-SF11. A broadband beam through a catalogue-glass boundary is sampled by wavelength and visibly disperses into a spectrum.
The catalogue options use published Sellmeier curves, so GDD follows the actual traced distance and is generally within a few percent where those curves are valid. Absorption bands and temperature are not modeled; per-surface transmission is a flat configured number rather than a computed coating or bulk loss. Circular-arc segments are true 2D arcs, but the whole element is still a 2D cross-section — it represents a freeform profile, not a true freeform 3D surface. Nested or overlapping glass bodies are not surface-merged.