# Cemented triplet

> Three glasses in one cemented stack — a bit more correction than a simple doublet.

![Cemented triplet](https://www.loomrume.com/optics/stills/cemented-triplet.png)

**Carl August von Steinheil** · 1866 — Steinheil aplanats

Three glasses cemented into one barrel: another surface, another chance to kill leftover colour and spherical error. Steinheil’s Munich shop sold aplanatic triplets for photography and telescopes in the 1860s.

A [Cooke triplet](https://www.loomrume.com/examples/cooke-triplet.md) later did a similar job with air between the elements. This one is the glued version — white in, a tighter spot on the meter, a little residual fan if you look for it.

## Sources

- [Carl August von Steinheil](https://en.wikipedia.org/wiki/Carl_August_von_Steinheil)
- [Triplet lens](https://en.wikipedia.org/wiki/Triplet_lens)

## Links

- [HTML](https://www.loomrume.com/examples/cemented-triplet)
- [Open in Studio](https://www.loomrume.com/experiments/new?template=cemented-triplet)
- [llms.txt](https://www.loomrume.com/llms.txt)