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Calcium Fluoride Plano-Concave Lenses, AR-Coated: 2 - 5 µm


  • Broadband AR Coating Optimized for the 2 - 5 µm Range
  • Choose from Ø1/2" or Ø1"

LC5269-E

LC5919-E

Related Items


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Common Specifications
Substrate Material Vacuum-Grade Calcium Fluoridea
AR Coating Range 2 - 5 µm
Reflectance over Coating Range (Avg.) <1.25%
Diameters Available 1/2" or 1"
Diameter Tolerance +0.0/-0.1 mm
Thickness Tolerance ±0.1 mm
Focal Length Tolerance ±1%
Surface Quality 40-20 Scratch-Dig
Surface Flatness
(Plano Side)
λ/2
Spherical Surface Power
(Concave Side)b
3λ/2
Surface Irregularity
(Peak to Valley)
λ/2
Centration <3 arcmin
Clear Aperture >90% of Diameter
Design Wavelength 588 nm
  • Click Link for Detailed Specifications on the Substrate
  • 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.
Zemax Files
Click on the red Document icon next to the item numbers below to access the Zemax file download. Our entire Zemax Catalog is also available.

Features

  • Vacuum-Grade Calcium Fluoride Substrate
  • Ø1/2" and Ø1" Versions Available
  • Broadband AR Coating for the 2 - 5 μm Range
  • Focal Lengths from -18.0 mm to -500.0 mm

Thorlabs' Ø1/2" and Ø1" Calcium Fluoride (CaF2) Plano-Concave Lenses have a broadband AR coating optimized for the 2 µm to 5 μm spectral range deposited on both surfaces. This coating greatly reduces the surface reflectivity of the substrate, yielding an average transmission in excess of 97% over the entire AR coating range. See the Graphs tab for detailed information.

Optic Cleaning Tutorial

CaF2 is commonly used for applications requiring high transmission in the infrared and ultraviolet spectral ranges. The material exhibits a low refractive index, varying from 1.35 to 1.51 within its usage range of 180 nm to 8.0 μm. Calcium fluoride is also fairly chemically inert and offers superior hardness compared to its barium fluoride, magnesium fluoride, and lithium fluoride cousins.

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 should face the source in order 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.

See the tables below for individual lens specifications. These lenses are also available uncoated.

Optical Coatings and Substrates
Lens Tutorial
Selection Guide
Other MIR Lenses

2 - 5 µm AR Coating Graphs

CaF2 -E Reflectance
Click to Enlarge

Click Here for Raw Data
Shown above is a graph of the measured percent reflectance of the AR coating as a function of wavelength. The average reflectance in the 2 - 5 μm range is <1.25%. The blue shading indicates the region for which the AR coating is optmized. Performance outside of the specified range is not guaranteed and varies from lot to lot. The Excel file above provides the coating curve data over an extended wavelength range.
CaF2 Transmission 3 to 5 micron antireflective coating
Click to Enlarge

Click Here for Raw Data
Shown above is a graph of the measured percent transmission of the AR coating as a function of wavelength. The blue shading indicates the region for which the AR coating is optmized. Performance outside of the specified range is not guaranteed and varies from lot to lot. The Excel file above provides the coating curve data over an extended wavelength range.
CaF2 Uncoated Transmission
Click to Enlarge

Click Here for Raw Data
Shown above is a graph of the measured transmission of an uncoated, 5 mm thick sample of CaF2.

Total Transmission of Optic (CaF2 Substrate, Uncoated)

The table below gives the approximate theoretical transmission of these uncoated optics for a few select wavelengths in the 0.18 - 8.0 μm range. To see an Excel file that lists all measured transmission values for this wavelength range, please click here.

Wavelength (μm) Total Transmission
0.2 0.910
0.4 0.929
0.6 0.935
0.8 0.937
1.0 0.938
1.2 0.938
1.4 0.938
1.6 0.938
1.8 0.939
2.0 0.939
Wavelength
(μm)
Total Transmission
2.2 0.939
2.4 0.939
2.6 0.940
2.8 0.940
3.0 0.940
3.2 0.941
3.4 0.941
3.6 0.941
3.8 0.942
4.0 0.942
Wavelength
(μm)
Total Transmission
4.2 0.943
4.4 0.943
4.6 0.943
4.8 0.944
5.0 0.945
5.2 0.945
5.4 0.945
5.6 0.946
5.8 0.946
6.0 0.947
Wavelength
(μm)
Total Transmission
6.2 0.947
6.4 0.947
6.6 0.948
6.8 0.949
7.0 0.949
7.2 0.948
7.4 0.947
7.6 0.946
7.8 0.945
8.0 0.944

Wavelength-Dependent Focal Length Shift

The paraxial focal length of a lens is wavelength dependent. The focal length listed below for a given lens corresponds to the value at the design wavelength (i.e., the focal length at 588 nm). Since CaF2 offers high transmission from 0.18 - 8.0 µm, users may wish to use these lenses at other popular wavelengths. Click on the icons below to view theoretically-calculated focal length shifts for wavelengths within the 0.18 - 8.0 µm range.

The blue shading indicates the region for which the AR coating is optimized. Please see the Graphs tab for more information.

Ø1/2" Plano-Concave Lenses

Item # LC5919-E LC5749-E
Focal Length @ 588 nm -18.0 mm -25.0 mm
Focal Length Shift
(Click for Details)
Raw Data
(Click to Download)
Data Data

Ø1" Plano-Concave Lenses

Item # LC5269-E LC5401-E LC5289-E LC5952-E LC5893-E
Focal Length @ 588 nm -40.0 mm -75.0 mm -100.0 mm -200.0 mm -500.0 mm
Focal Length Shift
(Click for Details)
Raw Data
(Click to Download)
Data Data Data Data Data
CXY1 in 30 mm Cage System
Click to Enlarge

CXY1 Translation Mount and
SM1 Lens Tube Mounted in a
30 mm Cage System
Threaded Mounting Adapter
Click to Enlarge

Ø1" Optic Mounted in a
ST1XY-S XY Translator

Click to Enlarge

LMR1 Fixed Mount with Ø1" Lens

Click to Enlarge

LM2XY Translating Mount with Ø2" Lens
Recommended Mounting Options for Thorlabs Lenses
Item # Mounts for Ø2 mm to Ø10 mm Optics
Imperial Metric
(Various) Fixed Lens Mounts for Small Optics, Ø5 mm to Ø10 mm
(Various) Small Optic Adapters for Use with Standard Fixed Lens Mounts, Ø2 mm to Ø10 mm
Item # Mounts for Ø1/2" (Ø12.7 mm) Optics
Imperial Metric
LMR05 LMR05/M Fixed Lens Mount for Ø1/2" Optics
LM05XY LM05XY/M Translating Lens Mount for Ø1/2" Optics
SCP05 16 mm Cage System, XY Translation Mount for Ø1/2" Optics
(Various) Ø1/2" Lens Tubes,
Optional SM05RRC Retaining Ring for High-Curvature Lenses (See Below)
Item # Mounts for Ø1" (Ø25.4 mm) Optics
Imperial Metric
LMR1 LMR1/M Fixed Lens Mount for Ø1" Optics
LM1XY LM1XY/M Translating Lens Mount for Ø1" Optics
ST1XY-S ST1XY-S/M Translating Lens Mount with Micrometer Drives (Other Drives Available)
CXY1 30 mm Cage System, XY Translation Mount for Ø1" Optics
(Various) Ø1" Lens Tubes,
Optional SM1RRC Retaining Ring for High-Curvature Lenses (See Below)
Item # Mounts for Ø2" (Ø50.8 mm) Optics
Imperial Metric
LMR2 LMR2/M Fixed Lens Mount for Ø2" Optics
LM2XY LM2XY/M Translating Lens Mount for Ø2" Optics
CXY2 60 mm Cage System, XY Translation Mount for Ø2" Optics
(Various) Ø2" Lens Tubes,
Optional SM2RRC Retaining Ring for High-Curvature Lenses (See Below)
Item # Adjustable Optic Mounts
Imperial Metric
LH1 LH1/M Adjustable Mount for Ø0.28" (Ø7.1 mm) to Ø1.80" (Ø45.7 mm) Optics
LH2 LH2/M Adjustable Mount for Ø0.77" (Ø19.6 mm) to Ø2.28" (Ø57.9 mm) Optics
VG100 VG100/M Adjustable Clamp for Ø0.5" (Ø13 mm) to Ø3.5" (Ø89 mm) Optics
SCL03 SCL03/M Self-Centering Mount for Ø0.15" (Ø3.8 mm) to Ø1.77" (Ø45.0 mm) Optics
SCL04 SCL04/M Self-Centering Mount for Ø0.15" (Ø3.8 mm) to Ø3.00" (Ø76.2 mm) Optics
LH160C LH160C/M Adjustable Mount for 60 mm Cage Systems,
Ø0.50" (Ø13 mm) to Ø2.00" (Ø50.8 mm) Optics
SCL60C SCL60C/M Self-Centering Mount for 60 mm Cage Systems,
Ø0.15" (Ø3.8 mm) to Ø1.77" (Ø45.0 mm) Optics

Mounting High-Curvature Optics

Thorlabs' retaining rings are used to secure unmounted optics within lens tubes or optic mounts. These rings are secured in position using a compatible spanner wrench. For flat or low-curvature optics, standard retaining rings manufactured from anodized aluminum are available from Ø5 mm to Ø4". For high-curvature optics, extra-thick retaining rings are available in Ø1/2", Ø1", and Ø2" sizes.

Extra-thick retaining rings offer several features that aid in mounting high-curvature optics such as aspheric lenses, short-focal-length plano-convex lenses, and condenser lenses. As shown in the animation to the right, the guide flange of the spanner wrench will collide with the surface of high-curvature lenses when using a standard retaining ring, potentially scratching the optic. This contact also creates a gap between the spanner wrench and retaining ring, preventing the ring from tightening correctly. Extra-thick retaining rings provide the necessary clearance for the spanner wrench to secure the lens without coming into contact with the optic surface.


Posted Comments:
mchen  (posted 2016-08-05 10:45:26.937)
Hi, We need LC5919 and LC5749 with D AR coating. Can you provide that? Thanks, Mike
kucirek  (posted 2013-08-15 17:07:34.86)
Do you offer or plan to offer concave spherical lenses AR-coated for 1.8-2.4µm as you do for plano-convex lenses ?
tcohen  (posted 2013-08-22 14:56:00.0)
Response from Tim at Thorlabs: Thank you for your feedback. We hadn’t had a formal plan for this but we are looking at it based on your inquiry. We can often do customs and in the meantime, we should be able to offer it for you this way. I will contact you to discuss this further.

Ø1/2" CaF2 Plano-Concave Lenses, AR-Coated: 2 - 5 µm

Item # Diameter Focal Length Dioptera Radius of Curvature Center Thickness Edge Thicknessb Back Focal Lengthc Reference
Drawing
LC5919-Ed 1/2" (12.7 mm) -18.0 mm -55.6 -7.8 mm 2.0 mm 5.3 mm -19.4 mm Plano-Concave Lens Drawing
LC5749-Ee 1/2" (12.7 mm) -25.0 mm -40.0 -10.8 mm 2.5 mm 4.6 mm -26.7 mm
  • Reciprocal of the Focal Length in Meters
  • Edge Thickness Given Before 0.2 mm at 45° Typical Chamfer
  • Measured at the Design Wavelength, 588 nm
  • Suggested Fixed Lens Mounts: LMR05(/M) & SM05L03
  • Suggested Fixed Lens Mount: LMR05(/M)
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
LC5919-E Support Documentation
LC5919-EØ1/2" CaF2 Plano-Concave Lens, f = -18.0 mm, AR-Coated: 2 - 5 µm
$179.63
Today
LC5749-E Support Documentation
LC5749-EØ1/2" CaF2 Plano-Concave Lens, f = -25.0 mm, AR-Coated: 2 - 5 µm
$168.81
Today

Ø1" CaF2 Plano-Concave Lenses, AR-Coated: 2 - 5 µm

Item # Diameter Focal Length Dioptera Radius of Curvature Center Thickness Edge Thicknessb Back Focal Lengthc Reference
Drawing
LC5269-Ed 1" (25.4 mm) -40.0 mm -25.0 -17.4 mm 2.0 mm 7.5 mm -41.4 mm Plano-Concave Lens Drawing
LC5401-Ee 1" (25.4 mm) -75.0 mm -13.3 -32.5 mm 2.5 mm 5.1 mm -76.8 mm
LC5289-Ee 1" (25.4 mm) -100.0 mm -10.0 -43.4 mm 3.0 mm 4.9 mm -102.1 mm
LC5952-Ee 1" (25.4 mm) -200.0 mm -5.0 -86.8 mm 3.5 mm 4.4 mm -202.4 mm
LC5893-Ee 1" (25.4 mm) -500.0 mm -2.0 -216.9 mm 4.0 mm 4.4 mm -502.8 mm
  • Reciprocal of the Focal Length in Meters
  • Edge thickness given before 0.2 mm at 45° typical chamfer.
  • Measured at the design wavelength, 588 nm.
  • Suggested Fixed Lens Mounts: LMR1(/M) & SM1L05
  • Suggested Fixed Lens Mount: LMR1(/M)
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
LC5269-E Support Documentation
LC5269-EØ1" CaF2 Plano-Concave Lens, f = -40.0 mm, AR-Coated: 2 - 5 µm
$233.74
Today
LC5401-E Support Documentation
LC5401-EØ1" CaF2 Plano-Concave Lens, f = -75.0 mm, AR-Coated: 2 - 5 µm
$222.91
Today
LC5289-E Support Documentation
LC5289-EØ1" CaF2 Plano-Concave Lens, f = -100.0 mm, AR-Coated: 2 - 5 µm
$217.51
Today
LC5952-E Support Documentation
LC5952-EØ1" CaF2 Plano-Concave Lens, f = -200.0 mm, AR-Coated: 2 - 5 µm
$209.93
Today
LC5893-E Support Documentation
LC5893-EØ1" CaF2 Plano-Concave Lens, f = -500.0 mm, AR-Coated: 2 - 5 µm
$204.52
Today
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