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Biconvex / Double Convex Lenses

Biconvex lenses also known as double convex lenses are simple optical lenses with two convex spherical surfaces, surfaces which bulge out from the center. These two convex surfaces have the same radius of curvature, and the lens focuses parallel rays of light to a single point beyond the lens. Double convex lenses play an important part in many imaging devices such as microscopes, cameras, telescopes, image relays. They are used to focus and control laser beams, and in telecom IR applications.   At Shanghai Optics we manufacture high quality biconvex lenses, both coated and uncoated,  for a wide range of beam-focusing applications.

The Figure above shows a point light-source located at the focal point of a biconvex lens (for generating a collimated beam.)


Applications of Biconvex Lenses

Although a biconvex lens or double convex lens is a simple lens they are often included in large multi-lens assemblies. Our biconvex lenses are most suited to applications where the object and virtual images are on different sides of the lens. Ideally, the conjugate ratios (ratio of the image and object distances) will be between 0.2 and 5, and distortions, chromatic aberration and spherical aberration are minimized when image and object are equidistant from the lens (1:1 conjugate ratio). When a more distant object must be imaged plano convex lenses may be preferred.


Biconvex Lens Specifications

Key specifications of a biconvex lens are the substrate, or optical material; focal length; diameter;  and radius of curvature.  The optical material used determines the durability of the lens, as well as optical properties like index and refraction.

The focal length of a biconvex lens is simply the distance from the lens to the focal point, measured along the focal axis. This measurement depends on the optical material used to make the lens as well as on the radius of curvature of the lens itself.

The radius of curvature is measured as the distance from the vertex of the lens surface to the center of curvature, measured along the optical axis. The two convex surfaces in a biconvex lens will have radii of curvature with equivalent absolute value but different signs.


Biconvex Lenses at Shanghai Optics

At Shanghai Optics we produce biconvex or double convex lenses with  K9 borosilicate crown glass, BK7 Schott glass, quartz, sapphire, fused silica, CaF2, ZnSe, and germanium substrates. Each of our lenses are carefully polished for optimal surface quality, and the edges are fine ground and beveled. We stock biconvex lenses suitable for UV, visible, and NIR ranges, and our factory standard in stock lenses have a diameter tolerance of ±0.01mm and flatness of λ/10.

Each Shanghai Optics lens is carefully tested for adherence to all applicable standards, using state of the art metrology equipment. We check and double check each piece before it leaves our factory, so that you can have full confidence that the optics you order will be optimally suited to your application.

Biconvex Lenses Specifications

Focal Length Tolerance +/-3%
Diameter Tolerance +/-0.05mm
Thickness Tolerance +/-0.03mm
Design Wavelength 546mm
Centration <1′
Surface Quality 40-20 scratch-dig
Edges Fine ground and beveled

In addition to our large catalogue of in-stock products, we are also able to supply custom lenses upon request. Please contact us to discuss manufacturing limits and custom options, or to receive an up-to-date catalogue of on-shelf options.

Contact us today for assistance with your custom biconvex lens project.


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