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What is a Double Concave Lens?

Apr. 19, 2023

1. Introduction to double concave lens

A double concave lens, also known as a biconcave lens, is a type of lens that has two concave (curving inward) surfaces. This means that the lens is thinner in the center and thicker at the edges, creating a negative lens that diverges light rays.

The imaging law of the concave lens is: when the object is a real object, it becomes an upright, reduced virtual image, and the image and the object are on the same side of the lens. The concave lens has a divergent effect on the light, so the lens is also called a divergent lens, a negative spherical lens. 

A Double Concave Lens cid=3

2. Features of biconcave lens:

A biconcave lens has a concave shape on both sides and features the same radius of curvature. Its negative focal length makes it useful for beam collimation, as well as for increasing or decreasing the focal length, and enlarging or shrinking images.

The double concave lens has a negative focal length and is often used in imaging or beam collimation applications. The coated lens is also widely used in visible light and near-infrared applications.

Conventional lens sizes are: Φ12.7mm, Φ25.4mm, Φ50.8mm, and customized double convex lenses can be produced according to customer project requirements.

3. Double concave lens parameters:

Our factory biconvex lens have a diameter tolerance of < + 0.00/ - 0.02mm and a flatness of < λ/5 @ 633nm. Focal length tolerance can be achieved < ± 1%


Optical Glass
Surface Flatness< λ/5 @ 633nm
Scratch/Dig< 40/20 (both sides)
Eccentricity ≤ 1arcmin
Focal Length Tolerance < ± 1%
Diameter Tolerance < + 0.00/ - 0.02mm
Thickness Tolerance < ± 0.05
Clear Aperture ≥ 95% of diameter
Coating AR OR BBAR
Diameter Range 5~260mm

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