Gaussian Beam

Fast practical design

Select realistic focal lengths before catalog search

A useful optical proposal should not begin with an exotic 217.22 mm lens merely because an unconstrained equation produced it. DiffBeam agents can start from common focal-length priors, preview the physics quickly, and search the real component catalog only when the user asks for purchasable hardware.

Ordinary lenses and telescope pairs

For first-pass spherical lenses, a sensible stock-like ladder is 10, 12.5, 15, 20, 25, 30, 40, 50, 60, 75, 100, 125, 150, 200, 250, and 300 mm. These are engineering priors, not claims that a specific vendor has a suitable coated optic in stock. For a telescope, compute the desired magnification first and select the closest focal-length ratio. Then solve or adjust the spacing while keeping the selected focal lengths fixed.

For example, a 3× afocal expander naturally suggests 25/75 mm, 50/150 mm, or 75/225 mm. The first two pairs use common values; the last contains a less universal 225 mm value and should not be the default unless total length or aperture constraints justify it.

Fiber collimators are different

Packaged fiber collimators and short aspheres often have characteristic effective focal lengths that are not round. Useful priors include 2.7, 3.1, 4.6, 6.2, 9.6, 11, 15.3, and 18.4 mm alongside round values. The agent should choose the value that produces the requested collimated radius, then use a following telescope if an exact final beam size is required. It must not attach a manufacturer or part number unless a catalog result actually supplies one.

When to call the catalog

  • Call search_lenses or search_fiber_collimators when the user asks what can be purchased, requests a real part number, names a coating or wavelength range, or imposes a diameter constraint.
  • Do not call the catalog before the first live preview when the user only wants an optical concept.
  • Distinguish a simulated ideal lens from a catalog result in the answer.
  • Never infer availability, coating performance, or stock status from a focal length alone.

This ordering keeps the interactive design fast: derive, choose a realistic prior, preview, and only then search. The Direct Agent Bridge is the default for an already-open workspace; the native MCP server exposes catalog tools and public simulations.

DiffBeam does not host or proxy a language model. It provides deterministic optics and catalog records so external agents can separate physical calculations from product claims.