Geometrical and Visual Optics: Basic Terms and Concepts

These flashcards cover basic terms and concepts in geometrical and visual optics, including electromagnetic radiation properties, vergence, refraction, Snell's Law, and the characteristics of image formation by spherical surfaces.

How are wavelength and frequency related in electromagnetic (EM) radiation?

They are inversely proportional; as wavelength increases, frequency decreases.

What is the specific wavelength range of visible radiation (light)?

Approximately 380 to 700 nm.

What is the relationship between wavelength and the energy of a photon?

As wavelength decreases, the amount of energy per photon increases, which is why short-wavelength radiation (like UV) is typically more damaging.

How does the curvature of a wavefront change as distance from a point source increases?

The curvature decreases as distance increases; at infinity, the wavefronts are flat.

What sign is assigned to the vergence of diverging light in optical problem solving?

A negative sign.

How is vergence in diopters (D) calculated given a distance?

By taking the reciprocal of the distance to the point source in meters (Vergence = 1/distance).

What is the refractive index of a material?

The ratio of the speed of light in a vacuum to its speed in that specific medium.

What does Snell's Law describe?

The relationship between indices of refraction and angles of incidence/refraction (n sin θ = n' sin θ').

When a light ray enters a medium with a higher index of refraction, which way does it bend?

It is refracted toward the normal to the surface.

What is the 'critical angle' in optics?

The specific angle of incidence at which the refracted ray travels parallel to the surface (90° refraction); exceeding this angle results in total internal reflection.

What is the secondary focal point (F') of a converging spherical surface?

The point to which parallel incident light rays converge after being refracted.

How are radius of curvature (r) and dioptric power (F) related?

They are inversely related; the shorter the radius (more curved), the greater the power.

What are the primary characteristics of a virtual image?

It is formed by diverging light rays, is erect (upright), and cannot be focused on a screen.

What are the characteristics of a real image formed by a converging spherical surface?

It is formed by converging light rays, is inverted, and can be focused on a screen.

What fundamental rule governs the 'vergence relationship' in optics?

Object vergence + surface power = image vergence (L + F = L').

In the linear sign convention used in this text, what direction is light assumed to travel?

From left to right.

What clinical device is used to reduce total internal reflection for viewing eye structures during glaucoma assessment?

A goniolens.