Utilize our free Lensmaker Equation Calculator to quickly determine the focal length of thin spherical lenses. Input the refractive index (n) and both radii of curvature (R1, R2) to instantly calculate the lens's optical power. Perfect for optical design and physics studies.
Formula:
Lensmaker's Equation Formula
The Lensmaker's Equation for a thin spherical lens is:
1/f = (n - 1) * (1/R1 - 1/R2)
Where:
- f: The focal length of the lens (in the same unit as R1 and R2).
- n: The refractive index of the lens material (dimensionless).
- R1: The radius of curvature of the first lens surface (facing the incident light).
- R2: The radius of curvature of the second lens surface.
Sign Convention for Radii of Curvature (R1, R2):
- Positive (+): If the center of curvature lies on the side of the surface where light exits the lens. (e.g., a convex surface from the left, R > 0).
- Negative (-): If the center of curvature lies on the side of the surface where light enters the lens. (e.g., a concave surface from the left, R < 0).
- Planar Surface (enter '0'): For a flat surface, the radius of curvature is considered infinite, and 1/R becomes 0 in the equation.