Types of Optical Lenses

Converging/Convex Lens

In this type of lens, when parallel rays interact with the lens, they converge to a single point upon passing through it. This focal point is referred to as the principal focus of the lens.

Diverging/Concave Lens

In the case of a diverging/concave lens, when parallel rays encounter the lens and pass through it, they diverge from a single point. This particular point is identified as the principal focus of the lens.

Elements of the Ray Diagram for Lenses

1. Principal Axis: This line perpendicular to the lens axis divides it into two. It encompasses the optical center (O) of the lens, the principal focus (F), and the center of curvature (C).
2. Lens Axis: This vertical line represents the central axis of the lens.
3. Optical Center (O): It signifies the point where the Principal Axis intersects the Lens Axis.
4. Principal Focus (F): These points are located on both sides of the lens. Parallel rays passing through the lens converge at the principal focus.
5. Focal Length (f): It corresponds to the distance between the Principal Focus (F) and the Optical Center (O) of the lens.
6. Center of Curvature (C): This point lies on the Principal Axis and is positioned at a distance of 2f from the optical center of the lens.

Principles for Creating Ray Diagrams for Lenses

1. If a ray runs parallel to the principal axis, it will intersect the Principal Focus on the opposite side of the lens after traversing it.
2. A ray that passes through the Optical Center will maintain its original path without any deviation.
3. When a ray passes through the principal focus, it will exit the lens parallel to the principal axis after going through it.