optician

[Fr. opticien.] 1. One who is versed in the science of optics. 2. One who makes or deals in optical gla es and instruments. "The aid which these sciences have received from the optician."-Stewart: Of the Human Mind, pt. ii., § 1. (Introd.) õp-tics, s. [OPTIC.] Physics: Optics was defined by Sir David Brew ster as that branch of knowledge which treats of the properties of light and of vision as performed by the human eye. He divided his treatise on the subject into four parts: 1. On the Reflection and Refraction of light: (1) Catoptrics (q. v.), (2) Dioptrics (q. v.). 2. Physical Optics. 3. On the application of optical principles to the explanation of Natural Phenomena. 4. Of Optical Instruments. The more modern division of the science is into: 1. Sources of Light; 2. Transmi ion, Velocity, and Intensity of Light; 3. Reflection of Light-Mirrors; 4. Single Refraction-Lenses; 5. Dispersion and Achromatism; 6. Optical Instruments; 7. The eye considered as an Optical Instrument; 8. Phosphor escence and Fluorescence; and 9. Double Refrac tion, Interference, and Polarization.