A biconvex lens has two convex surfaces, with a longer focal length in the middle and a shorter focal length at the edges, resulting in a positive focal length. This type of lens is primarily used to converge light from a point source or to transfer images to other optical systems.
The working principle of an optical biconvex lens is based on the law of refraction. When light transitions from one medium to another, its direction of propagation changes according to this law. In a biconvex lens, light enters the lens from the air and then exits back into the air, undergoing refraction at each interface. Due to the curvature of the lens surfaces and the differing refractive indices of the materials, the light rays follow specific paths through the lens, leading to the convergence or divergence of the light.
In imaging systems, biconvex lenses are often used as objective lenses or eyepieces to magnify small objects or to produce clear images of distant objects. For example, in a microscope, a biconvex lens serves as the objective lens, converging light from the object to form a magnified real image. This image is then further magnified by the eyepiece, ultimately presenting a detailed view to the observer.
Specifications | Commercial spec. | High precision spec. |
Material | UV glass (quartz, fused silica） | |
VIS glass (Schott, CDGM, HOYA, etc.) | ||
Diameter | Ø5mm~Ø600mm | |
Diameter tolerance | ±0.1mm | ±0.05mm |
Focal length tolerance | ±2% | ±1% |
Surface quality | 60/40 | 40/20 |
Centration | < 3 arc min | <1arc min |
Surface figure | 3λ | 2λ |
Surface irregularity | 1/4λ | 1/10λ |
Clear aperture | >85% of dia | >90% of dia |
Bevel | <0.2mm x 45deg | <0.1mm x 45deg |
Coating | Up on clients’ request | |
Type No. | Diameter | Focal length | Edge thickness | Center thickness | Back focal length | Radius of curvature |
φD( mm) | f( mm) | Te( mm) | Tc( mm) | fb( mm) | r( mm) | |
BK7-5-6 | 5 | 6 | 1.5 | 2.5 | 5.6 | 6.23 |
BK7-5-8 | 5 | 8 | 1.4 | 2.1 | 7.6 | 8.30 |
BK7-5-10 | 5 | 10 | 1.3 | 1.9 | 9.7 | 10.38 |
BK7-5-25 | 5 | 25 | 1.1 | 1.3 | 24.8 | 25.95 |
BK7-6-6 | 6 | 6 | 1.0 | 2.5 | 5.6 | 6.23 |
BK7-6-8 | 6 | 8 | 1.0 | 2.1 | 7.6 | 8.30 |
BK7-6-10 | 6 | 10 | 1.0 | 1.9 | 9.7 | 10.38 |
BK7-6-20 | 6 | 20 | 1.0 | 1.4 | 19.8 | 20.76 |
BK7-7-10 | 7 | 10 | 1.9 | 3.1 | 9.5 | 10.38 |
BK7-7-12 | 7 | 12 | 1.8 | 2.8 | 11.5 | 12.46 |
BK7-7-20 | 7 | 20 | 1.7 | 2.3 | 19.6 | 20.76 |
BK7-8-8 | 8 | 8 | 1.5 | 3.1 | 9.5 | 8.30 |
BK7-8-12 | 8 | 12 | 1.5 | 2.8 | 11.5 | 12.46 |
BK7-8-25 | 8 | 25 | 1.5 | 2.1 | 24.6 | 25.95 |
BK7-10-10 | 10 | 10 | 2.0 | 4.6 | 9.2 | 10.38 |
BK7-10-20 | 10 | 20 | 2.0 | 3.2 | 19.5 | 20.76 |
BK7-10-25 | 10 | 25 | 2.0 | 3.0 | 24.5 | 25.95 |
BK7-10-50 | 10 | 50 | 2.0 | 2.5 | 49.6 | 51.90 |
BK7-10-60 | 10 | 60 | 2.0 | 2.4 | 59.6 | 62.28 |
BK7-10-70 | 10 | 70 | 2.0 | 2.3 | 69.6 | 72.66 |
BK7-10-100 | 10 | 100 | 2.0 | 2.2 | 99.6 | 103.80 |
BK7-12.7-13 | 12.7 | 13 | 2.0 | 5.5 | 11.0 | 12.46 |
BK7-12.7-25 | 12.7 | 25 | 2.0 | 3.6 | 24.4 | 25.95 |
BK7-12.7-30 | 12.7 | 30 | 2.0 | 3.3 | 29.5 | 31.14 |
BK7-12.7-50 | 12.7 | 50 | 2.0 | 2.8 | 49.5 | 51.90 |
BK7-15-15 | 15 | 15 | 2.0 | 5.9 | 14.0 | 15.57 |
BK7-15-25 | 15 | 25 | 2.0 | 4.2 | 24.3 | 25.95 |
BK7-15-30 | 15 | 30 | 2.0 | 3.8 | 29.4 | 31.14 |
BK7-15-50 | 15 | 50 | 2.0 | 3.1 | 49.5 | 51.90 |
BK7-15-60 | 15 | 60 | 2.0 | 2.9 | 59.5 | 62.28 |
BK7-15-80 | 15 | 80 | 2.0 | 2.7 | 79.6 | 83.04 |
BK7-15-100 | 15 | 100 | 2.0 | 2.5 | 99.6 | 103.80 |
BK7-20-20 | 20 | 20 | 2.0 | 7.1 | 18.8 | 20.76 |
BK7-20-26 | 20 | 26 | 2.0 | 6.0 | 24.0 | 25.95 |
BK7-20-50 | 20 | 50 | 2.0 | 3.9 | 49.3 | 51.90 |
BK7-20-100 | 20 | 100 | 2.0 | 3.0 | 99.5 | 103.80 |
BK7-20-150 | 20 | 150 | 2.0 | 2.6 | 149.6 | 155.70 |
BK7-25-26 | 25 | 26 | 2.0 | 8.4 | 23.5 | 25.95 |
BK7-25-50 | 25 | 50 | 2.0 | 5.1 | 49.2 | 51.90 |
BK7-25-60 | 25 | 60 | 2.0 | 4.5 | 59.2 | 62.28 |
BK7-25-80 | 25 | 80 | 2.0 | 3.9 | 79.4 | 83.04 |
BK7-25-100 | 25 | 100 | 2.0 | 3.5 | 99.4 | 103.80 |
BK7-25-200 | 25 | 200 | 2.0 | 2.8 | 199.5 | 207.60 |
BK7-25.4-26 | 25.4 | 26 | 1.8 | 8.4 | 23.6 | 25.95 |
BK7-25.4-36 | 25.4 | 36 | 1.8 | 6.4 | 33.9 | 36.33 |
BK7-25.4-50 | 25.4 | 50 | 1.9 | 5.1 | 49.2 | 51.90 |
BK7-25.4-60 | 25.4 | 60 | 1.9 | 4.5 | 59.2 | 62.28 |
BK7-25.4-80 | 25.4 | 80 | 1.9 | 3.9 | 79.3 | 83.04 |
BK7-25.4-100 | 25.4 | 100 | 1.9 | 3.5 | 99.4 | 103.80 |
BK7-25.4-200 | 25.4 | 200 | 2.0 | 2.8 | 199.6 | 207.60 |
BK7-30-30 | 30 | 30 | 2.0 | 9.7 | 28.3 | 31.14 |
BK7-30-50 | 30 | 50 | 2.0 | 6.4 | 51.9 | 51.90 |
BK7-30-80 | 30 | 80 | 2.0 | 4.7 | 79.2 | 83.04 |
BK7-30-120 | 30 | 120 | 2.0 | 4.0 | 119.5 | 124.56 |
BK7-30-150 | 30 | 150 | 2.0 | 3.4 | 149.4 | 155.70 |
BK7-30-180 | 30 | 180 | 2.0 | 3.0 | 179.5 | 186.50 |
BK7-30-200 | 30 | 200 | 2.0 | 3.1 | 199.5 | 207.60 |
BK7-40-50 | 40 | 50 | 2.0 | 10.0 | 48.3 | 51.90 |
BK7-40-100 | 40 | 100 | 2.0 | 5.9 | 99.0 | 103.80 |
BK7-50-50 | 50 | 50 | 3.0 | 16.0 | 47.3 | 51.90 |
BK7-50-100 | 50 | 100 | 3.0 | 9.1 | 98.5 | 103.80 |
BK7-50-150 | 50 | 150 | 3.0 | 7.0 | 148.8 | 155.70 |
BK7-50-200 | 50 | 200 | 3.0 | 6.0 | 199.0 | 207.60 |
BK7-50-250 | 50 | 250 | 3.0 | 5.1 | 248.9 | 259.20 |
BK7-50-300 | 50 | 300 | 3.0 | 5.1 | 299.3 | 311.20 |
BK7-50.8-100 | 50.8 | 100 | 3.0 | 10.3 | 96.4 | 103.80 |
BK7-50.8-150 | 50.8 | 150 | 3.0 | 7.8 | 147.3 | 155.70 |
BK7-50.8-200 | 50.8 | 200 | 3.0 | 6.5 | 197.7 | 207.60 |
BK7-50.8-250 | 50.8 | 250 | 3.0 | 5.8 | 248.0 | 259.50 |
BK7-50.8-300 | 50.8 | 300 | 3.0 | 5.4 | 298.1 | 311.40 |
BK7-100-200 | 100 | 200 | 3.0 | 15.2 | 197.5 | 207.60 |
BK7-100-300 | 100 | 300 | 3.0 | 11.1 | 298.2 | 311.40 |
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