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N-BK7, UV Fused Silica Biconcave Lenses

  • Double concave structure recommended for absolute conjugate ratio close to 1:1
  • Made from N-BK7 (excellent  transmission from visible to the NIR region) and UV Fused Silica (superior transmission from UV to NIR)
  • Standardized focal lengths and diameters convenient for OEM
  • Various standard and custom coating options, focal lengths (standard -6 to -100mm)
  • Applications: Galilean laser beam expander, optical character readers, viewers, and projectors
  • Custom Biconcave Lenses made from different materials are available
Inquire for custom product  
Code Material Diameter CT ET Focal length Coating Unit Price Delivery Cart
1108-001 UV Fused Silica 6.0mm 2.5mm 4.1mm -6mm Uncoated Inquire 1 Week
1108-002 UV Fused Silica 6.0mm 3.0mm 3.8mm -12mm Uncoated Inquire 1 Week
1108-003 UV Fused Silica 9.0mm 2.5mm 5.0mm -9mm Uncoated Inquire 1 Week
1108-004 UV Fused Silica 9.0mm 3.0mm 4.2mm -18mm Uncoated Inquire 1 Week
1108-005 UV Fused Silica 12.7mm 3.0mm 6.0mm -15mm Uncoated Inquire 1 Week
1108-006 N-BK7 12.7mm 2.5mm 4.1mm -25mm Uncoated Inquire 1 Week
1108-006A N-BK7 12.7mm 2.5mm 4.1mm -25mm 350-650nm AR Coating Inquire 1~2 Weeks
1108-006B N-BK7 12.7mm 2.5mm 4.1mm -25mm 650-1050nm AR Coating Inquire 1~2 Weeks
1108-006C N-BK7 12.7mm 2.5mm 4.1mm -25mm 1050-1580nm AR Coating Inquire 1~2 Weeks
1108-007 UV Fused Silica 12.7mm 3.0mm 4.8mm -25mm Uncoated Inquire 1 Week
1108-008 N-BK7 12.7mm 3.0mm 4.3mm -30mm Uncoated Inquire 1 Week
1108-008A N-BK7 12.7mm 3.0mm 4.3mm -30mm 350-650nm AR Coating Inquire 1~2 Weeks
1108-008B N-BK7 12.7mm 3.0mm 4.3mm -30mm 650-1050nm ART Coating Inquire 1~2 Weeks
1108-008C N-BK7 12.7mm 3.0mm 4.3mm -30mm 1050-1580nm AR Coating Inquire 1~2 Weeks
1108-009 UV Fused Silica 12.7mm 3.0mm 4.5mm -30mm Uncoated Inquire 1 Week
1108-010 N-BK7 12.7mm 3.5mm 4.3mm -50mm Uncoated Inquire 1 Week
1108-010A N-BK7 12.7mm 3.5mm 4.3mm -50mm 350-650nm AR Coating Inquire 1~2 Weeks
1108-010B N-BK7 12.7mm 3.5mm 4.3mm -50mm 650-1050nm AR Coating Inquire 1~2 Weeks
1108-010C N-BK7 12.7mm 3.5mm 4.3mm -50mm 1050-1580nm AR Coating Inquire 1~2 Weeks
1108-011 UV Fused Silica 12.7mm 3.0mm 3.9mm -50mm Uncoated Inquire 1 Week
1108-012 UV Fused Silica 25.4mm 3.0mm 10.5mm -25mm Uncoated Inquire 1 Week
1108-013 N-BK7 25.4mm 3.0mm 6.1mm -50mm Uncoated Inquire 1~2 Weeks
1108-013A N-BK7 25.4mm 3.0mm 6.1mm -50mm 350-650nm AR Coating Inquire 1~2 Weeks
1108-013B N-BK7 25.4mm 3.0mm 6.1mm -50mm 650-1050nm AR Coating Inquire 1 Week
1108-013C N-BK7 25.4mm 3.0mm 6.1mm -50mm 1050-1580nm AR Coating Inquire 1~2 Weeks
1108-014 UV Fused Silica 25.4mm 3.5mm 7.0mm -50mm Uncoated Inquire 1 Week
1108-015 N-BK7 25.4mm 3.5mm 5.6mm -75mm Uncoated Inquire 1 Week
1108-015A N-BK7 25.4mm 3.5mm 5.6mm -75mm 350-650nm AR Coating Inquire 1~2 Weeks
1108-015B N-BK7 25.4mm 3.5mm 5.6mm -75mm 650-1050nm AR Coating Inquire 1~2 Weeks
1108-015C N-BK7 25.4mm 3.5mm 5.6mm -75mm 1050-1580nm AR Coating Inquire 1~2 Weeks
1108-016 UV Fused Silica 25.4mm 3.5mm 5.8mm -75mm Uncoated Inquire 1 Week
1108-017 N-BK7 25.4mm 4.0mm 5.6mm -100mm Uncoated Inquire 1 Week
1108-017A N-BK7 25.4mm 4.0mm 5.6mm -100nm 350-650nm AR Coating Inquire 1~2 Weeks
1108-017B N-BK7 25.4mm 4.0mm 5.6mm -100mm 650-1050nm AR Coating Inquire 1~2 Weeks
1108-017C N-BK7 25.4mm 4.0mm 5.6mm -100mm 1050-1580nm AR Coating Inquire 1~2 Weeks
1108-018 UV Fused Silica 25.4mm 3.5mm 5.3mm -100mm Uncoated Inquire 1 Week

Biconcave Lenses or Double Concave Lenses are optical lenses with two inward-bent spherical surfaces of identical radii of curvature. A double concave lens has a negative focal length and diverges a collimated light beam to the virtual focal point (that is the point at which the extension lines of the diverging light path intersect at the object side of the concave lens) and increases the focal lengths of a lens group. The usages of Biconcave lenses are diversified, encompassing divergence of collimated or focused light beams, and beam diameter modulation (e.g. Galilean beam expanders), and because of their negative focal lengths, bi-concave lenses could also be applied in the correction of spherical aberration of optical assemblies. Due to its symmetric structure, a double concave lens works best when the conjugate ratio (object distance: image distance) is close or equal to 1:1. In such situations, the distortion, spherical/chromatic aberration, and coma could be offset as a result of the equilibrium of the lenses. Whilst, when the intended magnification ratio is <1/5 or >5, a plano concave lens will be a better alternative.

This page features Shalom EO’s Off-the-shelf N-BK7 Double Concave Lenses and UV Fused Silica Double Concave Lenses

N-BK7 or its equivalent known as H-K9L is a ROHS-compliant borosilicate crown glass with a high transmission rate in the spectral range from visible to near-infrared (350-2200nm) and is probably the most frequently-chosen optical glass to manufacture professional optical components. The most attractive advantage of N-BK7 is its high optical homogeneity, which means its refractive indexes will only vary within a small amplitude. Besides, the hardness, chemical, and aberration resistance of N-BK7 are also very remarkable, it contains low levels of inclusions and bubbles, therefore N-BK7 is excellent for making high-precision optical lenses.

UV Fused Silica, equivalently known as JGS1, is an optical glass material with incomparably superior transparency to the UV wavelengths, meanwhile also being transparent to visible and NIR radiations (transmission range 200-2200nm). In fact, UV Grade Fused Silica is one of the best ultraviolet-transmitting media. The thermal properties of UVFS are prominent, too, including high-temperature durability and low thermal expansion. Other benefits of UV Fused Silica lenses encompass few bubbles/striae, high homogeneity, and advantages of birefringent properties. Therefore UVFS lens is the primary option for building a stable optical system under harsh working conditions.

Shalom EO’s stock N-BK7 Bi-concave Lenses have four standard coating options: uncoated, 350-650nm, 650-1100nm, and 1050-1580nm broadband anti-reflection (BBAR) coatings. The stock UV Fused Silica Bi-concave Lenses only have uncoated versions so far. While custom V-coatings that exhibit optimized transmission and low-cost MgF2 AR coatings with various transmission wavelengths could be furnished onto the N-BK7 and UVFS biconcave lenses upon request as well. Besides the stocked N-BK7 and UV Fused Silica Biconcave lenses, Shalom EO also provides custom biconcave lenses made from BaF2, CaF2, MgF2, Ge, ZnSe, Sapphire, and other optical materials. 

Specifications:

TypeBiconcave LensesMaterialN-BK7(H-K9L) or UV Fused Silica(JGS1)
Clear Aperture>90%Diameter Tolerance+0.00/-0.1mm
Thickness Tolerance±0.1mmSurface Irregularityλ/4 @ 633 nm
Concentricity3 arcminFocal Length Tolerance+/-1%
Chamfer0.2mm x 45 degree


Dia6.0mm EFL-6mm UV Fused Silica Biconcave Lenses Uncoated

Dia6.0mm EFL-6mm UV Fused Silica Biconcave Lenses Uncoated

Dia12.7mm EFL-25mm N-BK7 Biconcave Lenses 1050-1580nm AR Coating

Dia12.7mm EFL-25mm N-BK7 Biconcave Lenses 1050-1580nm AR Coating

Dia9.0mm EFL-9mm UV Fused Silica Biconcave Lenses Uncoated

Dia9.0mm EFL-9mm UV Fused Silica Biconcave Lenses Uncoated