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Calcium Fluoride Bi-Convex Lenses, AR Coated: 2 - 5 µm


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

LB5774-E

LB5766-E

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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%
Diameter Tolerance +0.00/-0.10 mm
Thickness Tolerance ±0.1 mm
Focal Length Tolerance ±1%
Surface Quality 40-20 (Scratch-Dig)
Spherical Surface Powerb 3λ/2
Spherical 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.

Features

  • Vacuum-Grade Calcium Fluoride Substrate
  • Ø1/2" and Ø1" Versions Available
  • Broadband AR Coating for the 2 - 5 μm Range
  • Focal Lengths from 15.0 mm to 200.0 mm

Thorlabs' Ø1/2" and Ø1" Calcium Fluoride (CaF2) Bi-Convex Lenses are available uncoated or with 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 95% over the entire AR coating range. See the Graphs tab for detailed information.

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.

Bi-convex lenses are popular for many finite imaging applications. Both surfaces are spherical and have the same radius of curvature, minimizing aberrations in situations where the object and image distances are equal or nearly equal. As a guideline, bi-convex lenses are the best choice for minimizing aberrations if the conjugate ratio (object distance : image distance) is between 5:1 and 1:5. Outside this range, plano-convex lenses are usually preferred.

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.
Optic Cleaning Tutorial
Optical Coatings and Substrates
Selection Guide
Other MIR Lenses

2 - 5 µm AR Coating Graphs

CaF2 -E Reflectance
Click to Enlarge

Click Here for an Excel File with Plot Data
Shown above is a graph of the measured percent reflectance of the enhanced 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 an Excel File with Plot Data
Shown above is a graph of the measured percent transmission of the enhanced 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 Transmission

CaF2 Uncoated Transmission
Click to Enlarge

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

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" Bi-Convex Lenses

Item #LB5766-ELB5922-ELB5864-E
Focal Length @ 588 nm15.0 mm20.0 mm40.0 mm
Focal Length Shift
(Click for Details)
Raw Data
(Click to Download)
DataDataData

Ø1" Bi-Convex Lenses

Item #LB5774-ELB5284-ELB5247-ELB5552-ELB5454-E
Focal Length @ 588 nm25.4 mm50.0 mm75.0 mm100.0 mm200.0 mm
Focal Length Shift
(Click for Details)
Raw Data
(Click to Download)
DataDataDataDataData
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.


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Ø1/2" CaF2 Bi-Convex Lenses, AR Coated: 2 - 5 µm

Item # Diameter Focal Length Dioptera Radius of Curvature Center Thickness Edge Thicknessb Back Focal Lengthc Reference
Drawing
LB5766-E 1/2" (12.7 mm) 15.0 mm +66.6 12.1 mm 5.6 mm 2.0 mm 12.9 mm Bi-Convex Lens Drawing
LB5922-E 1/2" (12.7 mm) 20.0 mm +50.0 16.6 mm 4.5 mm 2.0 mm 18.4 mm
LB5864-E 1/2" (12.7 mm) 40.0 mm +25.0 34.2 mm 3.2 mm 2.0 mm 38.9 mm

Suggested Fixed Lens Mount: LMR05(/M)

  • Reciprocal of the Focal Length in Meters
  • Edge Thickness Given Before 0.2 mm at 45° Typical Chamfer
  • Measured at Design Wavelength, 588 nm
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
LB5766-E Support Documentation
LB5766-E Ø1/2" CaF2 Bi-Convex Lens, f = 15.0 mm, AR-Coated: 2 - 5 µm
$204.52
Today
LB5922-E Support Documentation
LB5922-E Ø1/2" CaF2 Bi-Convex Lens, f = 20.0 mm, AR-Coated: 2 - 5 µm
$204.52
Today
LB5864-E Support Documentation
LB5864-E Ø1/2" CaF2 Bi-Convex Lens, f = 40.0 mm, AR-Coated: 2 - 5 µm
$204.52
Today

Ø1" CaF2 Bi-Convex Lenses, AR Coated: 2 - 5 µm

Item # Diameter Focal Length Dioptera Radius of Curvature Center Thickness Edge Thicknessb Back Focal Lengthc Reference
Drawing
LB5774-E 1" (25.4 mm) 25.4 mm +39.4 20.2 mm 11.0 mm 2.0 mm 21.2 mm Bi-Convex Lens Drawing
LB5284-E 1" (25.4 mm) 50.0 mm +20.0 42.5 mm 5.9 mm 2.0 mm 47.9 mm
LB5247-E 1" (25.4 mm) 75.0 mm +13.3 64.4 mm 4.5 mm 2.0 mm 73.4 mm
LB5552-E 1" (25.4 mm) 100.0 mm +10.0 86.2 mm 3.9 mm 2.0 mm 98.6 mm
LB5454-E 1" (25.4 mm) 200.0 mm +5.0 173.1 mm 2.9 mm 2.0 mm 199.0 mm

Suggested Fixed Lens Mount: LMR1(/M)

  • Reciprocal of the Focal Length in Meters
  • Edge Thickness Given Before 0.2 mm at 45° Typical Chamfer
  • Measured at Design Wavelength, 588 nm
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
LB5774-E Support Documentation
LB5774-E Ø1" CaF2 Bi-Convex Lens, f = 25.4 mm, AR-Coated: 2 - 5 µm
$228.33
Today
LB5284-E Support Documentation
LB5284-E Ø1" CaF2 Bi-Convex Lens, f = 50.0 mm, AR-Coated: 2 - 5 µm
$228.33
Today
LB5247-E Support Documentation
LB5247-E Ø1" CaF2 Bi-Convex Lens, f = 75.0 mm, AR-Coated: 2 - 5 µm
$228.33
Today
LB5552-E Support Documentation
LB5552-E Ø1" CaF2 Bi-Convex Lens, f = 100.0 mm, AR-Coated: 2 - 5 µm
$228.33
Today
LB5454-E Support Documentation
LB5454-E Ø1" CaF2 Bi-Convex Lens, f = 200.0 mm, AR-Coated: 2 - 5 µm
$228.33
Today
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