In geometrical optics, the ray approximation is combined with the laws of reflection, refraction and geometry to determine the location and size of an image formed by a reflecting or refracting surface. This approach can be applied to single surfaces such as mirrors, multiple surfaces such as lenses and multicomponent systems such as telescopes. Optical science is relevant in many related disciplines including astronomy, various engineering fields, photography and medicine particularly ophthalmology and optometry.
Holmarc's Liquid Lens Apparatus (Model: HO-ED-O-01) is designed for the determination of refractive index of a given liquid.
Geometrical Optics Experiment Apparatus (Model No. HO-ED-O-02) is developed for general physics education in universities and colleges.