Pertaining to a narrow opening, slit, or pinhole in an opaque barrier that limits the amount of light entering an optical system or the eye. Stenopaeic slits are used to isolate specific meridians of vision and reduce optical aberrations by increasing the depth of field. In optical testing, these devices help determine if visual blur is caused by refractive errors or internal scattering.
Heard on the job
We used a stenopaeic slit during the alignment check to isolate the astigmatism in the primary lens.