Brewster (unit)

{{Short description|Non-sI unit used to measure the susceptibility of a material to photoelasticity}}

The brewster (B) is a non-SI unit used to measure the susceptibility of a material to photoelasticity, or the value of the stress-optic coefficient of the material. The unit has dimensions reciprocal to those of stress. One brewster is defined to be equal to $10^\{-12\}$ square metres per newton (m²/N or 1/Pa) or $10^\{-13\}$ square centimetres per dyne (cm²/dyn).{{Cite web |title=eFunda: Glossary: Units: Photoelastic Work: Brewster |url=https://www.efunda.com/glossary/units/units--photoelastic_work--brewster.cfm |access-date=2024-01-03 |website=www.efunda.com}} The unit is named after David Brewster, who discovered stress-induced birefringence in 1816.