Magnesium Fluoride Plano-Convex Lenses, Uncoated

  • Wavelength Range: 200 nm - 6 µm Uncoated
  • Average Transmission >90% from 200 nm to 6 µm
  • Extremely Durable and Rugged in the UV to the IR


LA6004 Lens Shown Mounted
in an LMR1 Fixed Lens Mount

Related Items

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Material Vacuum-Grade Magnesium Fluoride
Wavelength Range 200 nm - 6 μm
Diameter Tolerance +0.00/-0.10 mm
Thickness Tolerance ±0.2 mm
Focal Length Tolerance ±2% at 633 nm
Surface Quality 40-20 Scratch-Dig
Surface Flatness
(Plano Side)
Spherical Surface Powera
(Convex Side)
Surface Irregularity
(Peak to Valley)
Centration ≤3 arcmin
Clear Aperture >90% of Diameter
Alignment of C-Axis <20 armin
Index of Refraction 1.376981 @ 630 nm
Coating None
  • 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.


  • Wavelength Range: 200 nm - 6.0 μm
  • Material: Vacuum-Grade MgF2

Thorlabs' MgF2 Plano-Convex lenses are popular for many applications in the UV and IR. These lenses are an ideal choice for applications from 200 nm to 6.0 μm. Magnesium Fluoride is extremely durable in comparison to other materials that reach this far down into the UV or out into the IR. The C-axis is oriented to minimize birefringence.

Optic Cleaning Tutorial

Plano-Convex lenses have a positive focal length and approach best form for infinite and finite conjugate applications. These lenses focus a collimated beam to the back focus and collimate light from a point source. They are designed with minimal spherical aberration and have a focal length which can be calculated using a simplified thick lens equation:

f= R/(n-1),

where n is the index of refraction and R is the radius of curvature of the lens surface. To minimize the introduction of spherical aberration, a collimated light source should be incident on the curved surface of the lens when being focused and a point light source should be incident on the planar surface when being collimated.

Plano-Convex Lens kits are also available - please click here for information.

Optical Coatings
Lens Tutorial
Selection Guide
Magnesium Fluoride Lenses
Other MIR Lenses
Other Spherical Singlets

Transmission Curve for Magnesium Fluoride: 10 mm Thick Uncoated Sample, Surface Reflections are Included in the Transmission Plot

Transmission Curve for Magnesium Fluoride
Click to Enlarge

Click here for raw data.

CXY1A in 30 mm Cage System
Click to Enlarge

CXY1A 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 and Mini-Series 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
MLH05 MLH05/M Mini-Series 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)
CXY1A 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 # Mount for Ø1.5" Optics
Imperial Metric
LMR1.5 LMR1.5/M Fixed Lens Mount for Ø1.5" Optics
(Various) Ø1.5" Lens Tubes,
Optional SM1.5RR Retaining Ring for Ø1.5" Lens Tubes and Mounts
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:
user  (posted 2022-03-09 05:24:30.2)
MgF2 window (WG61050) is specified to be transmissive (>50%) at 120nm. Is it also the case for these lenses?
jgreschler  (posted 2022-03-10 03:33:39.0)
Thank you for reaching out to Thorlabs. Yes the window and the lens share a substrate and will share a transmission curve. We have more information about our optical substrates here
Lawrence Trask  (posted 2021-09-01 15:32:37.847)
Greetings, our group is interested in focusing 2 um light into a PPLN. Is it possible to make an MgF2 lens with a different focal length? For example, one with a focal length of 120 mm?
YLohia  (posted 2021-09-03 08:31:40.0)
Hello, custom optics can be requested by emailing We will discuss the possibility of offering this customization directly.
christian.zimmermann  (posted 2016-08-05 11:17:53.79)
Hei, can you tell me, if the MgF2 lenses can be used for low Temperature applications (down to ca. 30 K)? Best regards, Christian Zimmermann
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Ø1" MgF2 Plano-Convex Lenses

Item # Diameter Focal Length Radius of
Back Focal
200 nm 486 nm 633 nm 2.0 µm
LA6002 1" 44.7 mm 49.7 mm 50.1 mm 51.4 mm 18.9 mm 6.9 mm 2.0 mm 45.0 mm Plano-Convex Lens Drawing
LA6004 1" 66.8 mm 74.4 mm 75 mm 76.9 mm 28.3 mm 5.0 mm 2.0 mm 71.4 mm
LA6005 1" 89.3 mm 99.4 mm 100.3 mm 102.8 mm 37.8 mm 4.3 mm 2.1 mm 97.1 mm
LA6006 1" 133.8 mm 148.9 mm 150.1 mm 153.9 mm 56.6 mm 3.2 mm 1.8 mm 147.7 mm
LA6007 1" 178.2 mm 198.3 mm 200 mm 205.0 mm 75.4 mm 3.2 mm 2.1 mm 197.7 mm
LA6008 1" 222.9 mm 248 mm 250.1 mm 256.4 mm 94.3 mm 2.8 mm 1.9 mm 248.0 mm
LA6009 1" 445.5 mm 495.8 mm 500 mm 512.5 mm 188.5 mm 2.6 mm 2.2 mm 498.1 mm
LA6010 1" 891.1 mm 991.6 mm 1000 mm 1024.9 mm 377.0 mm 2.4 mm 2.2 mm 998.3 mm

Suggested Fixed Lens Mounts: LMR1(/M)

  • Edge Thickness prior to chamfer (0.2 mm at 45° typical).
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
LA6002 Support Documentation
LA6002Ø1" Magnesium Fluoride Plano-Convex Lens, f=50 mm
LA6004 Support Documentation
LA6004Ø1" Magnesium Fluoride Plano-Convex Lens, f=75 mm
LA6005 Support Documentation
LA6005Ø1" Magnesium Fluoride Plano-Convex Lens, f=100 mm
LA6006 Support Documentation
LA6006Ø1" Magnesium Fluoride Plano-Convex Lens, f=150 mm
LA6007 Support Documentation
LA6007Ø1" Magnesium Fluoride Plano-Convex Lens, f=200 mm
LA6008 Support Documentation
LA6008Ø1" Magnesium Fluoride Plano-Convex Lens, f=250 mm
LA6009 Support Documentation
LA6009Ø1" Magnesium Fluoride Plano-Convex Lens, f=500 mm
LA6010 Support Documentation
LA6010Ø1" Magnesium Fluoride Plano-Convex Lens, f=1000 mm