Uncoated N-BK7 Bi-Concave Lenses
Uncoated N-BK7 Bi-Concave Lenses
Our uncoated N-BK7 precision bi-concave (double-concave) lenses are polished to tight tolerances using master test plates to ensure minimum wavefront distortion for demanding laser collimating applications.
- Uncoated double-concave shape for beam expansion applications
- High performance 40-20 scratch-dig N-BK7 substrates
- Standardized focal lengths across different lens sizes See All Features
| Compare | Description | Drawings, CAD & Specs | Avail. | Price | ||
|---|---|---|---|---|---|---|
 | KBC010 Uncoated N-BK7 Bi-Concave LensesBi-Concave Lens, N-BK7, 6.35 mm Diameter, -12.5 mm EFL, Uncoated | |||||
| KBC013 Uncoated N-BK7 Bi-Concave LensesBi-Concave Lens, N-BK7, 6.35 mm Diameter, -6.3 mm EFL, Uncoated | |||||
 | KBC016 Uncoated N-BK7 Bi-Concave LensesBi-Concave Lens, N-BK7, 12.7 mm Diameter, -100 mm EFL, Uncoated | |||||
| KBC019 Uncoated N-BK7 Bi-Concave LensesBi-Concave Lens, N-BK7, 12.7 mm Diameter, -75 mm EFL, Uncoated | |||||
| KBC022 Uncoated N-BK7 Bi-Concave LensesBi-Concave Lens, N-BK7, 12.7 mm Diameter, -50 mm EFL, Uncoated | |||||
| KBC025 Uncoated N-BK7 Bi-Concave LensesBi-Concave Lens, N-BK7, 12.7 mm Diameter, -25 mm EFL, Uncoated | |||||
| KBC028 Uncoated N-BK7 Bi-Concave LensesBi-Concave Lens, N-BK7, 12.7 mm Diameter, -12.5 mm EFL, Uncoated | |||||
 | KBC031 Uncoated N-BK7 Bi-Concave LensesBi-Concave Lens, N-BK7, 25.4 mm Diameter, -200 mm EFL, Uncoated | |||||
| KBC034 Uncoated N-BK7 Bi-Concave LensesBi-Concave Lens, N-BK7, 25.4 mm Diameter, -150 mm EFL, Uncoated | |||||
| KBC037 Uncoated N-BK7 Bi-Concave LensesBi-Concave Lens, N-BK7, 25.4 mm Diameter, -100 mm EFL, Uncoated |
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.
Note: besides the diameter, please check the Edge Thickness (Te) specification of the lens and the lens mount to ensure compatibility before purchasing.
| Lens Diameter |  A-Line™ Lens Mounts |
 LT Series Lens Tubes |
 LP Series Lens Positioners |
 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.
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.
AR.14 Broadband Visible Antireflection Coating
Our AR.14 broadband multilayer antireflection coating markedly improves the transmission efficiency of these lenses by reducing surface reflections over a 430-700 nm wavelength range. This visible AR coating performs effectively for multiple visible wavelengths and tunable lasers eliminating the need for several sets of optics. It features a damage threshold of 7.5 J/cm2 for 10 ns pulses at 10 Hz and 532 nm.
Advantages to Uncoated Lenses
Uncoated lenses are used in optical systems and devices because they have an exceptionally wide wavelength range, a high damage threshold ratio, and without the expense of coatings, are always less expensive than their coated counterparts. Further, uncoated lenses give camera images a “vintage” look, which is becoming popular in cinema film production.
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.
