Ray Optics Fundamentals

Ray Optics Fundamentals

• Ray optics is a simplified model of light propagation, treating light as rays—straight lines representing the direction of light.
• This model is useful for analyzing optical instruments like lenses and mirrors.
• Key principles are the law of reflection and refraction (Snell's Law).
• The law of reflection states the incident angle equals the reflected angle.
• Snell's Law links incident angle, refracted angle, and refractive indices of different media.

Reflection

• Reflection occurs when light bounces off a surface.
• The angle of incidence is between the incident ray and the surface normal.
• The angle of reflection is between the reflected ray and the surface normal.
• Specular reflection creates parallel reflected rays from a smooth surface.
• Diffuse reflection scatters reflected rays from a rough surface.

Refraction

• Refraction is light bending when transitioning between media.
• This bending is due to differing light speeds in different media.
• Refractive index measures light slowdown relative to vacuum.
• Refractive index is the ratio of light speed in a vacuum to the speed in the medium.
• Snell's Law relates the incident and refracted angles to the refractive indices.

Lenses

• Lenses, transparent with curved surfaces, refract light to form images.
• Converging (convex) lenses focus parallel light at a focal point.
• Diverging (concave) lenses spread parallel light as if from a focal point behind the lens.
• Focal length is the distance from the lens to its focal point.
• Images can be real or virtual, depending on object position.
• Image size can vary based on focal length and object distance.

Mirrors

• Mirrors reflect light, forming images.
• Plane mirrors create upright, same-size virtual images.
• Spherical mirrors (concave or convex) produce real or virtual images, depending on the object's position.
• Concave mirrors can produce magnified real images.
• Convex mirrors always form diminished virtual images.
• Spherical mirror focal length is half its radius of curvature.

Image Formation

• Images in ray optics are formed by light ray intersection or apparent intersection.
• Real images form where rays actually intersect, projected onto screens.
• Virtual images appear where rays seem to intersect, not projected.
• Image characteristics (real/virtual, magnified/reduced, upright/inverted) depend on object position.

Applications of Ray Optics

• Ray optics has applications in telescopes, microscopes, cameras, optical fibers, medical devices, and lighting systems.
• Optical instruments utilize reflection and refraction principles.