A biconcave lens is a type of lens with two equally curved concave surfaces and a negative focal length, primarily used to diverge light rays. The concave surfaces on both sides cause parallel incoming light rays to diverge outward after passing through the lens, forming a virtual focal point.
The characteristics of a biconcave lens include having equal radii of curvature on both surfaces and a negative focal length. Parallel incoming light rays diverge after passing through the lens, forming a virtual focal point. This type of lens plays an important role in optical systems, as it can increase the focal length and is used in various optical applications.
Optical biconcave lenses have a wide range of applications in various fields:
1. Beam Expansion: Biconcave lenses are commonly used in beam expansion systems to increase the diameter of the beam by dispersing light, making them suitable for applications that require a wide beam range.
2. Projection Applications: In projection systems, biconcave lenses can help adjust and focus light, ensuring clear image display.
3. Focal Length Extension in Optical Systems: By combining biconcave lenses, the focal length range of optical systems can be effectively extended, making them suitable for various optical instruments and devices.
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) | |
BK7-6-6 | 6 | -6 | 3.0 | 1.5 | -6.7 | 6.75 |
BK7-10-10 | 10 | -10 | 4.6 | 2.0 | -10.3 | 10.38 |
BK7-10-15 | 10 | -15 | 3.6 | 2.0 | -15.3 | 15.57 |
BK7-10-20 | 10 | -20 | 3.2 | 2.0 | -20.3 | 20.76 |
BK7-12.7-15 | 12.7 | -15 | 4.7 | 2.0 | -15.4 | 15.57 |
BK7-12.7-25 | 12.7 | -25 | 3.6 | 2.0 | -25.4 | 59.95 |
BK7-15-15 | 15 | -15 | 5.9 | 2.0 | -15.3 | 15.57 |
BK7-15-20 | 15 | -20 | 4.8 | 2.0 | -20.3 | 20.76 |
BK7-15-50 | 15 | -50 | 3.1 | 2.0 | -50.3 | 51.90 |
BK7-20-20 | 20 | -20 | 7.1 | 2.0 | -20.3 | 20.76 |
BK7-20-30 | 20 | -30 | 5.3 | 2.0 | -30.3 | 31.14 |
BK7-20-50 | 20 | -50 | 3.9 | 2.0 | -50.3 | 51.90 |
BK7-25-50 | 25 | -50 | 5.1 | 2.0 | -50.3 | 51.90 |
BK7-25-100 | 25 | -100 | 3.5 | 2.0 | -100.3 | 103.80 |
BK7-25-200 | 25 | -200 | 2.9 | 2.0 | -201 | 204.5 |
BK7-25.4-25 | 25.4 | -25 | 8.6 | 2.0 | -25.4 | 25.95 |
BK7-25.4-50 | 25.4 | -50 | 5.2 | 2.0 | -50.4 | 51.90 |
BK7-25.4-100 | 25.4 | -100 | 3.6 | 2.0 | -100.4 | 103.80 |
BK7-25.4-200 | 25.4 | -200 | 2.8 | 2.0 | -200.4 | 207.60 |
BK7-30-30 | 30 | -30 | 9.7 | 2.0 | -30.3 | 31.14 |
BK7-30-50 | 30 | -50 | 6.4 | 2.0 | -50.3 | 51.90 |
BK7-30-60 | 30 | -60 | 5.7 | 2.0 | -60.3 | 62.28 |
BK7-30-80 | 30 | -80 | 4.7 | 2.0 | -80.3 | 83.04 |
BK7-50-50 | 50 | -50 | 15.8 | 3.0 | -50.5 | 51.90 |
BK7-50-60 | 50 | -60 | 13.5 | 3.0 | -60.5 | 62.28 |
BK7-50-70 | 50 | -70 | 11.9 | 3.0 | -70.5 | 72.66 |
BK7-50-100 | 50 | -100 | 9.1 | 3.0 | -100.5 | 103.80 |
BK7-50.8-50 | 50.8 | -50 | 16.3 | 3.0 | -50.3 | 51.90 |
BK7-50.8-60 | 50.8 | -60 | 13.8 | 3.0 | -60.5 | 62.28 |
BK7-50.8-100 | 50.8 | -100 | 9.3 | 3.0 | -100.5 | 103.80 |
BK7-50.8-150 | 50.8 | -150 | 7.2 | 3.0 | -150.5 | 155.70 |
BK7-50.8-200 | 50.8 | -200 | 6.1 | 3.0 | -200.5 | 207.60 |
BK7-50.8-250 | 50.8 | -250 | 5.5 | 3.0 | -250.5 | 259.50 |
BK7-50.8-300 | 50.8 | -300 | 5.1 | 3.0 | -300.5 | 311.40 |
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