Spherical Lenses for Optics: A Complete Guide

A spherical lens is an optical lens with one or both surfaces shaped like a segment of a sphere. These lenses are common because they are easy to design, manufacture, and inspect. They are widely used in imaging, laser systems, microscopes, and other optical devices.

Applications of Spherical Lenses

Spherical lenses are used to converge or diverge light, forming smaller or larger images:

Cameras: Focus images onto small sensors for digital capture.

Microscopes: Magnify tiny objects for viewing.

Laser systems and measurement devices: Control light for precision applications.

Types of Spherical Lenses

Lenses are classified by surface curvature:

Plano-Concave (PCV): Flat + concave surface; diverges light.

Plano-Convex (PCX): Flat + convex surface; converges light.

Meniscus: Concave + convex; reduces spherical aberration.

Biconvex: Both surfaces convex; strongly converges light.

Biconcave: Both surfaces concave; diverges light.

Some lenses combine a spherical and a flat surface. Fully flat lenses are typically called optical windows.

How Spherical Lenses Are Made

Manufacturing usually involves:

Preform cutting or molding

Grinding to achieve precise curvature

Polishing for smooth, clear surfaces

Centering and edging to align optical and mechanical axes

Cleaning with ultrasonic machines

Coating to improve transmission and durability

Materials for Spherical Lenses

Lens material is chosen based on:

Refractive index and light behavior

Chromatic dispersion

Wavelength range (UV, visible, IR)

Thermal or environmental conditions

Common materials include optical glass, fused silica, plastics, and sapphire for high-stress applications.

Cost Factors

Spherical lens prices vary from less than one USD to several thousand USD per piece. Cost is influenced by:

Material: Glass vs. sapphire or germanium

Size: Very small or very large lenses are more expensive

Optical quality: Surface finish and polishing precision

Order quantity: Larger batches reduce unit cost

Coatings: Batch-applied coatings affect price

Key Specifications

Focal length: Distance where light converges or diverges; determines lens power

Concentricity: Alignment of optical and mechanical centers; critical in multi-lens systems

Conclusion

Spherical lenses are versatile, reliable, and widely used in optics. Correct material selection, surface quality, and concentricity are essential to achieve optimal performance in cameras, microscopes, laser systems, and industrial applications.