DCV022, Uncoated Double-Concave Lenses, H-K9L/N-SF11 Optical Glass, D=25.40mm

  • DCV022, Uncoated Double-Concave Lenses, which are available in two materials: N-BK7 and N-SF11.
  • This Plano-concave lens with a diameter of 25.40mm, has different focal lengths for you to choose from, f-50mm, f-75mm, f-100mm.


CodeMaterialAR CoatingDiameter-mmFocal Length (EFL-mm)Radius of Curvature (R1-mm)Center Thickness (Tc-mm)Edge Thickness (Te-mm)
DCV022-01H-K9L (BK7)Uncoated25.4-50.0-
DCV022-02H-K9L (BK7)Uncoated25.4-75.0-77.863.55.6
DCV022-03H-K9L (BK7)Uncoated25.4-100.0-103.694.05.6

Uncoated Double-Concave Lenses

These uncoated Plano-Concave Lenses are made of BK7 (N-BK7) or N-SF11.

Since the Abbe number of N-SF11 (25.76) is smaller than the Abbe number of N-BK7 (64.17), the lens made of N-SF11 exhibits greater dispersion than the lens made of N-BK7.

  • N-BK7: 350-2000nm
  • N-SF11: 420-2300nm

Double-Concave Lenses are made of two concave surfaces with same radius, usually used in beam expansion applications, light projection, or focal length of expansion.

Tc---------- Center Thickness
Te---------- Edge Thickness
R1---------- Radius
Dia---------- Diameter

BFL ---------- Back Focal Length
EFL ---------- Effective Focal Length
H'-------------- Principal Point

Thickness Tolerance±0.1mm
Surface Accuracyλ/4 @632.8nm
Centering Tolerance<3 arcmin

Design Wavelength632.8nm
Focal Length Tolerance±1%
Diameter Tolerance+0.0/-0.1mm
Surface Quality40-20
Clear Apperture>90%

The focal length of the Double-concave lens is negative, which is the best choice for diverging convergent beam.

Similar to Plano-concave lenses, Double-concave lenses can spread a parallel beam to the virtual focus, as in a Galilean beam expander.

Double-Concave Lenses can also be coated with AR Coating

  • -A: AR@350-700nm,
  • -B: AR@650-1100nm,
  • -C: AR@1050-1700nm,

anti-reflection coating can reduce the reflectivity of each surface of the lens.


Uncoated-N-BK7 (10mm Thick Sample)


Uncoated N-SF11 (10mm Thick Sample)

Weight 80 g
Focal Length

f-50mm, f-75mm, f-100mm


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