Large field spectrographs are severely influenced by atmospheric refraction. We discuss the effect of differential refraction across the field as well as the chromatic effects for the Norris ...

WE are writing to direct attention to a source of error which may occur in spectroscopic investigation of the infra-red region of the spectrum. On reviewing the ...

Recent experiments that demonstrate the negative refraction of light could bring a heated scientific debate to a close, and give negative-index materials a positive future Figure 1: Negative-index ...

A new class of optical thin-film materials enables the refractive index to be tuned to extremely low values. E Fred Schubert and colleagues believe that this capability could have important ...

Please provide your email address to receive an email when new articles are posted on . It would seem logical that emmetropia is the ideal refractive state of the eye. Emmetropia puts far away objects ...

Refractive errors are common eye issues that can cause blurry or distorted vision. Treatment usually involves wearing glasses or contact lenses or getting procedures ...

Have you ever sat on the bottom of a swimming pool and pondered your watery ceiling? Most of the surface is a sheet of light blue, and you can't see through it, even though the water is clear. But ...