Common Specifications
Lens Shape	Plano / Concave
Substrate Material	N-BK7 (Grade A)
Wavelength Range^a	350 nm - 2.0 µm
Diameters Available	6 mm, 9 mm, 1/2", 25 mm, 1", or 2"
Diameter Tolerance	+0.0/-0.1 mm
Thickness Tolerance	±0.1 mm
Focal Length Tolerance	±1%
Design Wavelength	587.6 nm (Except Ø25 mm Lenses) 632.8 nm (Ø25 mm Lenses)
Index of Refraction @633 nm	1.515
Surface Quality	40-20 Scratch-Dig
Surface Flatness (Plano Side)	λ/2
Spherical Surface Power (Convex Side)^b	3λ/2
Surface Irregularity (Peak to Valley)	λ/4
Abbe Number	v_d=64.17
Centration	≤3 arcmin
Clear Aperture	>90% of Diameter

Also Available with -A coating for the 350 - 700 nm range, a -B coating for the 650-1050 nm range, or a -C coating for the 1050-1620 nm range
Much like surface flatness for flat optics, spherical surface power is a measure of the deviation between the surface of the curved optic and a calibrated reference gauge, typically for a 633 nm source, unless otherwise stated. This specification is also commonly referred to as surface fit.

Features

Material: N-BK7
Wavelength Range: 350 nm - 2.0 μm (Uncoated)
Choose from 6 Diameters: Ø6 mm, Ø9 mm, Ø1/2" (Ø12.7 mm), Ø25 mm,
Ø1" (Ø25.4 mm), or Ø2" (Ø50.8 mm)
Offers Excellent Transmittance Throughout the Visible and Near Infrared

These Plano-Concave lenses are fabricated from RoHS-compliant N-BK7 glass. N-BK7 is probably the most common optical glass used for high quality optical components. It is typically chosen whenever the additional benefits of UV fused silica (i.e., good transmission further into the UV and a lower coefficient of thermal expansion) are not necessary. However, for particularly harsh environments where the optic will be exposed to alkalis and acids, consider our N-SF11 plano-concave lenses.

Like all plano-concave lenses, these lenses have negative focal lengths and can be used to diverge collimated beams. In this case, the curved surface of the lens should face the source to minimize spherical aberration. In addition, they can be employed to offset the effects of spherical aberration caused by other lenses in an optical system.

N-BK7 lens kits are also available. Please click here for information.

Plano-Concave Lens Selection Guide
N-BK7	Uncoated -A (350 - 700 nm) -B (650 - 1050 nm) -C (1050 - 1620 nm)
N-SF11	Uncoated -A (350 - 700 nm) -B (650 - 1050 nm) -C (1050 - 1620 nm)
UV Fused Silica	Uncoated -UV (290 - 370 nm) -A (350 - 700 nm) -B (650 - 1050 nm) -C (1050 - 1620 nm)
CaF₂	Uncoated -E (3 - 5 µm)
ZnSe	-F (8 - 12 µm)

Custom Coatings are also available. Please contact our technical support staff for a quote.

Quick Links to Other Spherical Singlets
Plano-Convex	Bi-Convex	Best Form	Plano-Concave	Bi-Concave	Positive Meniscus	Negative Meniscus

Below is the transmission curve for N-BK7, a RoHS-compliant form of BK7. Total Transmission is shown for a 10 mm thick, uncoated sample and includes surface reflections.

Click Here for Raw Data
Click to Enlarge

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Posted Comments:

Poster: p.clark

Posted Date: 2013-04-05 12:18:10.543

Suggestion. It would be nice if 1 inch diameter plano-convex and plano-concave lenses were available in even increments of optical power (say, -4, -3, -2, -1, +1, +2, +3, +4 diopters). That would be focal lengths: -250, -333.33, -500, -1000, +1000, +500, +333.33, +400 mm. Very useful for through-focus studies of cameras, etc., and it would make a nice set, like the old ophthalmic trial lenses.

Poster: cdaly

Posted Date: 2013-04-18 14:12:00.0

Response from Chris at Thorlabs: We may be able to do some custom focal lengths, but typically these require a minimum order quantity. I will make this suggestion to our optics department and perhaps it can be offered as stock components in the future. I will contact you directly to discuss this further.

Poster: Laurie

Posted Date: 2009-01-05 09:46:40.0

Response from Laurie at Thorlabs to ali_mos: Thank you for your interest in our plano-concave lenses. Our coated lenses can handle powers of ~100W/cm^2 for CW light and 100 mJ/cm^2 for 10 ns pulses. The uncoated lenses can handle powers of ~2 kW/cm^2 for CW light and 3 J/cm^2 for 10 ns pulsed light. If you have additional questions, please feel free to contact our technical support staff.

Poster: ali_mos

Posted Date: 2009-01-02 20:00:14.0

I coudnt find the damage threshold of lenses which is very important, where can I find it?

Poster: technicalmarketing

Posted Date: 2008-02-13 10:38:41.0

Dear Mcneil I was unable to find the error you mentioned but you are correct. The information for SF11 is as follows: n=1.784720, Vd=25.7566, and Glass Code=785258. Thank you for providing your feedback.

Poster: dbmcneil

Posted Date: 2008-02-12 18:43:10.0

For SF11, you list the index of refraction as 1.515 and the glass code as 515/642. However, elsewhere, Ive seen the index listed as 1.785 and the glass code as 785/258. Looking at the listed Abbe number of 25.76, we only really have a choice of SF or LaSF glasses, which all have indexes of 1.75 mininum. Thus, I tend to think that your listed data might be in error.

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N-BK7 Plano-Concave Lenses, Uncoated

Features