Plano-concave lenses are best used when one conjugate distance is more than five times the other conjugate distance. The performance of this lens shape is best when the object and image distances are the same. The performance of this lens shape is best for an infinite conjugate ratio (focusing collimated light or collimating a point source).Д«i-convex lenses perform best when one conjugate distance is between 0.2 and 5 times the other conjugate distance. Plano-convex lenses are best used where one conjugate distance is more than five times the other conjugate distance. Each singlet lens shape minimizes aberrations for a certain conjugate ratio, defined as the ratio of the object distance to the image distance (these are called conjugate distances). Plano-convex and bi-convex lenses are positive (i.e., they have a positive focal length) and will bring collimated light to a focus, while plano-concave and bi-concave lenses are negative and will cause collimated light to diverge.

Each of these lenses is suited for different applications. Thorlabs offers several basic singlet designs: Plano-Convex, Bi-Convex, Plano-Concave, and Bi-Concave. More details about these other types of lenses can be found on the Achromatic Lenses and Aspheric Lenses tabs. For the most demanding applications, spherical singlets will not perform as well as achromatic lenses (for both broadband and monochromatic sources) or aspheric lenses (for monochromatic sources). Meniscus lenses are often employed in these multi-element optical systems, although they are rarely used alone. The use of multiple lens elements within a compound optical system can lead to further performance improvements. For better performance, best form lenses are optimized to reduce aberrations while still retaining spherical surfaces. For simple applications, standard plano-convex, plano-concave, bi-convex, and bi-concave lenses are sufficient. Spherical singlets are a good option for many situations where aberrations are not a great concern, as they are the simplest and most inexpensive type of lens to produce. Relay Imaging (Virtual Object and Image) Д«roadband Relay Imaging (Real Object and Image) Д«roadband Focusing, Collimation, and Relay Imaging Д¬orrection of All Primary Chromatic Aberrations More details can be found in the Spherical Singlets, Achromatic Lenses, Aspheric Lenses, and Lens Materials tabs on this page.

The table below gives an overview of the lenses offered by Thorlabs.

The surfaces of these lenses deviate from spherical sections, allowing for optimal aberration correction. For the best performance with monochromatic laser sources, aspheric optics are recommended. These multi-element optics also offer improved aberration correction for monochromatic light. For correction of chromatic aberration, achromatic lenses are ideal. In addition, their single-element design means that they exhibit chromatic aberration that prevents optimum performance with broadband light. As a general rule, spherical singlets are the most inexpensive, but they suffer from spherical aberration and other monochromatic aberrations. However, it is important to choose lenses that are appropriate for a given system. Thorlabs offers a wide variety of lenses with very different properties to match the needs of almost any application.

Better than system lens