Optical lenses come in many shapes and sizes – from plano-convex (PCX) to aspheric. Knowing the advantages and disadvantages of each lens type is crucial when choosing between optics as each has its own purpose. Understanding optical lens geometries helps anyone, from novice to expert, choose the best optical lens in any optical design.

Convexlens

Ideal for fiber coupling, endoscopy, and barcode scanning applications. Half ball lens version also available. For additional information, view Understanding Ball Lenses

Comprised of two inward, equally curved surfaces. Ideal for beam expansion, light projection, and expanding the focal length of an optical system. Also known as biconcave lenses.

Eyelens

Using the common terminologies from Table 1, it is easy to understand technical figures for each type of single lens element. Table 2 shows 10 of the most commonly used optical lenses and their typical applications. As optical technology advances, additional single-lens geometries such as focus-tunable lenses and assemblies such as telecentric lenses are becoming valuable tools for optical design. To learn more about telecentric lenses, view The Advantages of Telecentricity.

Convexlensimaging

Optical lenses are the most important tools in optical design for controlling light. When optical designers talk about optical lenses, they are either referring to a single lens element or an assembly of lens elements (Figure 1). Examples of single elements are plano-convex (PCX) lenses, double-convex (DCX) lenses, aspheric lenses, etc; examples of assemblies of elements are telecentric imaging lenses, infinity-corrected objectives, beam expanders, etc. Each combination is comprised of a series of lens elements and each element has a specific lens geometry which controls light in its own way.

Performs similar function as a PCX or DCX lens, but can provide smaller spot sizes and superior image quality. Achromatic lenses are useful for reducing spherical and chromatic aberration. Negative version for diverging light as available. For additional information, view Why Use an Achromatic Lens?

Before delving into each type of lens geometry, consider how optical lenses bend light using the property of refraction. Refraction is the means by which light is deviated by a certain amount when it enters or leaves a medium. This deviation is a function of the index of refraction of the medium and the angle the light makes with respect to the surface normal. This property is governed by Snell's Law of Refraction (Equation 1) where $ \small{n_1} $ is the index of the incident medium, $ \small{\theta_1} $ is the angle of the incident ray, $ \small{n_2} $ is the index of the refracted medium, and $ \small{\theta_2} $ is the angle of the refracted ray. Snell's Law describes the relationship between the angles of incidence and transmission when a ray travels between multiple media (Figure 2).

Cameralens

Output beams with a variety of focal ratios may be produced, depending on the numerical aperture of the microscope objective. Please see Calibration Optics for a description of the microscope objectives available from Kerry Optical Systems. Customer-owned RMS-threaded microscope objectives may also be be used.

The Collimating Lens Attachment (aka Transmission Sphere) slides into the 1.25″ inside diameter of the SPPDI® 2″ Telescope Adapter. The Collimating Lens Attachment comprises a commercial 1.25″ eyepiece extender tube, with an achromatic collimating lens installed in the narrow end, and an empty RMS-threaded microscope objective holder installed in the opposite end. The output collimated beam has a diameter of about 1/2″, which is presented at the rear aperture of the user-supplied microscope objective.

Fresnellens

lenses中文

Ideal for image relay, and for imaging of objects at close conjugates. Note: Aberrations will increase as the conjugate ratios increase. Also known as biconvex lenses.

Lens

Ideal for laser focusing or for replacing multiple spherical lens elements in a system. Useful for eliminating spherical aberration and greatly reducing other aberrations. For additional information, view All About Aspheric Lenses.

Ideal for collimation and focusing applications utilizing monochromatic illumination. Note: Orient the curved surface of a PCX lens towards the source for optimal performance.

Comprised of one flat and one inward curved surface. Ideal for beam expansion, light projection, and expanding the focal length of an optical system.

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All optical lenses obey Snell's Law of Refraction. Consequently, it is the optical lens geometry (i.e. the surface profile) that determines how light behaves as it propagates through the optical element. To understand the terminology used in optical lens specifications, consider 10 common terms (Table 1). For more detailed definitions and a list of additional terms, please view our Glossary.

Ideal for focusing laser light into a ring with a constant thickness. Note: A smaller apex angle generates a larger ring. For additional information, view An In-Depth Look at Axicons

When combined with a microscope objective, this attachment serves as a “transmission sphere.” When used as a transmission sphere, the output beam may be used for interferometry of a “fast” (