Compare Model Drawings, CAD & Specs Diameter Effective Focal Length (EFL) F/# Availability Price
Bi-Concave Lens, N-BK7, 6.35 mm Diameter, -12.5 mm EFL, 650-1000nm
$69
In Stock
6.35 mm -12.5 mm -1.9
In Stock
Bi-Concave Lens, N-BK7, 6.35 mm Diameter, -6.3 mm EFL, 650-1000nm
$69
In Stock
6.35 mm -6.3 mm -0.9
In Stock
Bi-Concave Lens, N-BK7, 12.7 mm Diameter, -100 mm EFL, 650-1000nm
$69
In Stock
12.7 mm -100 mm -7.8
In Stock
Bi-Concave Lens, N-BK7, 12.7 mm Diameter, -75 mm EFL, 650-1000nm
$69
In Stock
12.7 mm -75 mm -5.9
In Stock
Bi-Concave Lens, N-BK7, 12.7 mm Diameter, -50 mm EFL, 650-1000nm
$69
In Stock
12.7 mm -50 mm -3.9
In Stock
Bi-Concave Lens, N-BK7, 12.7 mm Diameter, -25 mm EFL, 650-1000nm
$69
In Stock
12.7 mm -25 mm -1.9
In Stock
Bi-Concave Lens, N-BK7, 12.7 mm Diameter, -12.5 mm EFL, 650-1000nm
$69
In Stock
12.7 mm -12.5 mm -0.9
In Stock
Bi-Concave Lens, N-BK7, 25.4 mm Diameter, -200 mm EFL, 650-1000nm
$71
In Stock
25.4 mm -200 mm -7.8
In Stock
Bi-Concave Lens, N-BK7, 25.4 mm Diameter, -150 mm EFL, 650-1000nm
$71
In Stock
25.4 mm -150 mm -5.9
In Stock
Bi-Concave Lens, N-BK7, 25.4 mm Diameter, -100 mm EFL, 650-1000nm
$71
In Stock
25.4 mm -100 mm -3.9
In Stock
Bi-Concave Lens, N-BK7, 25.4 mm Diameter, -75 mm EFL, 650-1000nm
$71
In Stock
25.4 mm -75 mm -2.9
In Stock
Bi-Concave Lens, N-BK7, 25.4 mm Diameter, -50 mm EFL, 650-1000nm
$71
In Stock
25.4 mm -50 mm -1.9
In Stock
Bi-Concave Lens, N-BK7, 25.4 mm Diameter, -25 mm EFL, 650-1000nm
$71
In Stock
25.4 mm -25 mm -0.9
In Stock
Bi-Concave Lens, N-BK7, 50.8 mm Diameter, -500 mm EFL, 650-1000nm
$99
In Stock
50.8 mm -500 mm -9.8
In Stock
Bi-Concave Lens, N-BK7, 50.8 mm Diameter, -250 mm EFL, 650-1000nm
$99
In Stock
50.8 mm -250 mm -4.9
In Stock
Bi-Concave Lens, N-BK7, 50.8 mm Diameter, -200 mm EFL, 650-1000nm
$99
In Stock
50.8 mm -200 mm -3.9
In Stock
Bi-Concave Lens, N-BK7, 50.8 mm Diameter, -150 mm EFL, 650-1000nm
$99
In Stock
50.8 mm -150 mm -2.9
In Stock
Bi-Concave Lens, N-BK7, 50.8 mm Diameter, -100 mm EFL, 650-1000nm
$99
In Stock
50.8 mm -100 mm -1.9
In Stock
Bi-Concave Lens, N-BK7, 50.8 mm Diameter, -75 mm EFL, 650-1000nm
$99
In Stock
50.8 mm -75 mm -1.4
In Stock

Specifications

  • Lens Shape
    Bi-Concave (Double-Concave)
  • Lens Material
    N-BK7
  • Antireflection Coating
    650-1000 nm
  • Coating Type
    NIR Multilayer
  • Coating Code
    AR.16
  • Damage Threshold
    7.5 J/cm2, 10 ns pulses, 10 Hz at 1064 nm
  • Surface Quality
    40-20 scratch-dig
  • Surface Accuracy, Irregularity
    λ/4
  • Surface Accuracy, Power
    1.5 λ
  • Surface Flatness
    λ/4
  • Centration
    ≤3 arc min
  • Chamfers
    0–0.8 mm face width
  • Chamfers Angle/Tolerance
    45° ±15°, typical
  • Focal Length Tolerance
    ±1 %
  • Diameter Tolerance
    +0/-0.1 mm
  • Center Thickness Tolerance
    ±0.1 mm
  • Clear Aperture
    ≥central 90% of diameter
  • Cleaning

Features

N-BK7 Substrates for VIS and NIR Applications

N-BK7 is an excellent lens material for most visible and near infrared applications. It is the most common borosilicate crown optical glass, and it provides great performance at a good value. Its high homogeneity, low bubble and inclusion content, and straightforward manufacturability make it a good choice for transmissive optics. N-BK7 is also relatively hard and shows good scratch resistance. The transmission range for BK 7 is 380 to 2100 nm. It is not recommended for temperature sensitive applications, such as precision mirrors. For more information, refer to our optical materials technical note.

Precision Bi-Concave Lens Surfaces

Our precision N-BK7 bi-concave lenses are polished to tight tolerances minimizing wavefront distortion. Tight surface quality tolerances minimize scatter and unwanted diffraction effects. These lenses have a 40-20 scratch-dig surface quality, and a λ/4 surface irregularity. For more information, refer to the optical surfaces technical note.

Broadband Multilayer NIR Antireflection Coatings

Our broadband AR.16 antireflection coating improves the transmission efficiency of these lenses by reducing surface reflections over a 650-1000 nm wavelength range. The NIR AR multi-layer coating improves the performance over uncoated surfaces. It features a damage threshold of 7.5 J/cm‌2 for 10 ns pulses at 10 Hz and 1064 nm.

Standardized Bi-Concave Focal Lengths

Standard double concave effective focal lengths provide a systematic approach allowing for lenses of different sizes and materials to be interchanged without requiring other changes to your optical system.

Bi-Concave Lens Shape for Beam Expansion

Bi-Concave lenses are the best choice where object and image are at absolute conjugate ratios closer to 1:1 with converging input beam. The output rays appear to be diverging from a virtual image located on the object side of the lens. The distance from this virtual point to the lens is known as the focal length. Similar to the Plano-Concave lenses, the Bi-concave lenses have negative focal lengths, thereby causing collimated incident light to diverge. Bi-Concave lenses have equal radius of curvature on both side of the lens. They are generally used to expand light or increase focal length in existing systems, such as beam expanders and projection systems.

Mounting Options

We offer a full range of optical lens mounts to meet various experimental requirements. Below lists the recommended mounts for spherical lenses of standard sizes. Please see our Lens Mount Guide for additional information.

Lens Diameter LH-A-GRP
A-Line™ Lens Mounts
LT_Series_group_update
LT Series Lens Tubes
OM-multi_axis_lens_pos-S
LP Series Lens Positioners
optics-cage-plus-S
Optics Cage Plus Series
76.2 mm (M-) LH-3A N/A N/A N/A
50.8 mm (M-) LH-2A
LH-2N
LT20-05
LT20-10
LT20-20
LT20-30
LP-2A
LP-2A-XY
LP-2A-XYZ
N/A
38.1 mm (M-) LH-1.5A LT20 lens tube with
LH-2R1.5 adapter
LP-2 lens positioner with
LPLH-1.5T adapter
N/A
25.4 mm (M-) LH-1A
LH-1N
LH-1XY
LH-1TZ-A
LH-1TZ
LT10-05
LT10-10
LT10-20
LT10-30
LP-1A
LP-1A-XY
LP-1A-XYZ
OC1-LH1-S
OC1-LH1
OC1-LH1-TZ
OC1-LH1-XY
OC1-LH1-XYA
OC1-LH1-XYC
OC1-LH1-XYZ
12.7 mm (M-) LH-0.5A
LH-05N
LT05-05
LT05-10
LP-05A
LP-05A-XY
LP-05A-XYZ
N/A
6.35 mm LH-05DB with
LH-50R25 adapter
LT05 lens tube with
LH-50R25 adapter
LP-05 lens positioner with
LPLH-25T adapter
N/A

For non-standard sizes not listed above, check out our variable size lens mounts.