A spheric lens is an optical lens that has a curved surface with a consistent curvature radius throughout the lens. Their construction causes light entering them to diverge or converge, depending on the lens design. The focal length of a concave spheric lens is negative, causing incident light to diverge (producing virtual images). In contrast, a convex spheric lens has a positive focal length, which can cause incident light to converge (creating real and virtual images). The formed real image is highly focused, while the formed virtual image is magnified.
Aspheric lens are optical lenses with rotationally symmetric non-spheric and non-cylindrical shapes. Unlike spheric lenses, their curvature radius varies from the center to the edge of the lens. Although the design and manufacture of aspheric lenses are challenging, if constructed correctly, they can provide more powerful optical functionality than similar spheric lenses. Some of the main benefits of using aspheric lenses in optical applications are: reduced number of components required in optical assemblies, reduced spheric aberrations, distortions, and edge glare effects, clearer focusing, larger aperture sizes, and improved light focusing and collection efficiency.
Due to the above reasons, aspheric lenses are used in many imaging applications. They are commonly used in imaging objectives of microscopes and other imaging lens components in life science instruments, semiconductor wafer inspection tools, medical devices, and defense and aerospace night vision imaging optical systems relying on precision optical components.
Spheric and aspheric lenses are used in a wide range of imaging applications in various end markets. They enable engineers, researchers, and scientists to use advanced devices such as microscopes, laser scanners, and other imaging equipment for highly accurate measurements. Some examples of applications where spheric and aspheric lenses are used include:
Fluorescence microscopy platforms: Researchers use aspheric lenses to facilitate identification and examination of specific parts of specimens (e.g., decoding DNA sequences and imaging individual cells and tissue samples).
Cameras for vision correction and laser-based eye care tools: Used by trained clinical and ophthalmic surgeons for diagnosis and treatment of eye diseases and vision correction.
Semiconductor wafer inspection tools: Used by computer chip engineers to plot defect maps and probe cards.
Industrial laser machine tools: Used by manufacturing companies to create and inspect products before, during, and after manufacturing.
Night vision optics: Used by frontline Marines and soldiers for critical defense tasks in dark concealment.