A biconvex lens is a lenticular lens sheet that includes an incident surface and an exit surface, and is characterized in that the focal length of the middle part of the lens surface is longer, and the focal length of the ends of each lens surface is shorter. The lenticular lens is mainly used to condense the light from a point light source or transmit an image to other optical systems.
Example with BK7 material: These N-BK7 biconvex lenses are available uncoated or with one of five antireflection coatings (-A, -AB, -B, -C, or -D), which reduce the amount of light reflected from each surface of the lens (see the Selection Guide table below for coating option). Since approximately 4% of the incident light is reflected at each surface of an uncoated substrate, the application of an AR coating improves transmission, which is important in low-light applications, and prevents the undesirable effects (e.g., ghost images) associated with multiple reflections. Having optics that are AR coated on both surfaces is particularly desirable for applications utilizing multiple optical elements. Please see the Graphs tab for additional coating information.
| N-BK7 Biconvex Lens Selection Guide | ||
| Coating name | wavelength band |  |
| Uncoated | Uncoated | |
| A Coating | 350nm-700nm | |
| AB Coating | 400nm-1100nm | |
| B Coating | 650nm-1050nm | |
| C Coating | 1050-1700nm | |
| D Coating | 1650nm-3000nm | |
