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Broadband Gradient-Index (GRIN) Lens

  • Gradient-Index Lens for Laser Scanning and Widefield Imaging
  • 0.5 Numerical Aperture in Water
  • 0.25 mm Working Distance on Sample Side
  • AR Coated for 500 - 1000 nm


Microscope Objective

Sample Plane



This GRIN lens can be used as a 1:1 imaging relay between the objective lens and the sample.

3.4 mm

Ø1.0 mm

Image Plane

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GRIN Parts
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500 µm Field of View
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200 µm Field of View 

Neuronal activity in an awake mouse. Both laser-scanned multiphoton images used the G2P10 GRIN lens implanted 3 mm deep and a 20X, 0.5 NA Nikon Objective Lens. Images courtesy of Dr. Mackenzie Mathis, Rowland Institute, Harvard University.


  • Use as an Implantable Lens Element for In Vivo Imaging Applications
  • Designed for Laser Scanning Microscopy
  • Broadband AR Coating for 500 - 1000 nm
  • Suitable for Excitation Wavelengths up to 1040 nm
  • Water Coupling on Sample Side and Air Coupling on Objective Side

Thorlabs' broadband gradient-index (GRIN) lens is available for imaging applications in which the region of interest is inaccessible with a microscope objective. The lens features a 0.25 mm working distance on the sample side and a 0.19 mm working distance on the objective side. It has a broadband AR coating optimized for 500 to 1000 nm wavelengths, which supports both widefield imaging techniques to locate the target region of interest (ROI) and multiphoton laser scanning of the sample. At 1 mm in diameter and 3.4 mm in length, this GRIN lens can be implanted deeply into a target specimen with minimal invasiveness and load. It provides a large collection angle due to a numerical aperture of 0.5 in water. See the Specs tab for more details on optical properties.

Unlike a traditional lens, a GRIN lens affects the optical path by varying the index of refraction within the lens itself. Additionally, in a GRIN lens, all optical path lengths (refractive index multiplied by distance) are the same due to the radially varying refractive index, in contrast to a spherical or aspheric lens. For information on how to calculate the refractive index as a function of radius, please see the Specs tab.

Note: this lens contains materials that might be toxic and is not recommended for prolonged periods of direct contact with live tissue. Click here to download a pdf of the SDS for this lens.

Design Wavelength 550 nm
AR Coating Range (Both Ends)
500 - 700 nm, Ravg < 0.5%
700 - 1000 nm, Ravg < 1.5%
Working Distancea 0.25 mm on Sample Side (Water Immersion)
0.19 mm on Objective Side (Dry)
Viewing Angle (Max) 70°
Refractive Index (n1)
1.666 @ 550 nm
Gradient Constant (√A)
0.782 mm-1 @ 550 nm
Pitchb (P)
0.423 @ 550 nm
Face Angle (θ)
Numerical Aperture (NA) 0.5 in Water
Magnification -1
Length (Z) 3.4 mm ± 0.085 mm
Diameter (D) 1 mm +0/-0.05 mm
Field Curvaturec 100 µm
Polarization Preservation 0.99
Operating Temperature
<200 °C
  • The working distance is the distance between the edge of the lens and the focus.
  • The "pitch" of the lens is the fraction of a full sinusoidal period that the ray traverses in the lens (i.e., a lens with a pitch of 0.25 has a length equal to 1/4 of a sine wave, which would collimate a point source located at the surface of the lens).
  • The field curvature is the difference in image positions at the lens center and at 80% of the lens radius. See the figure at the top right for details.
Microscopy Using a GRIN Lens
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Imaging Using a GRIN Lens
GRIN Lens AR Reflectance
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AR Coating Reflectance; Click Here for Raw Data

GRIN Lens Refractive Index Variation

Index as a Function of Radius
The index as a function of radius, as shown in the diagram to the bottom right, may be calculated with the equation:
Index as a Function of Radius
where n1 is the index of refraction on the optical axis, √A is the gradient constant, and r is the radial position (ranging from -D/2 to +D/2, where D is the diameter).

Relating Pitch and Lens Length
The pitch and length of a GRIN lens may be related using the following equation:
Relating Pitch and Lenght
where P is the pitch of the lens and Z is the length of the lens.


After opening the lens box, exercise extra care in lifting the plastic shield, as the G2P10 lens may cling to the shield and be lost during removal. The G2P10 should be handled with stainless steel tweezers, preferably those with a tapered end, and picked up by firmly grasping the side of the cylinder rather than the flat ends.


Use methyl alcohol as a cleaning solvent when necessary. Acetone may also be used without harm to the GRIN lens, but should be pure enough to not leave a residue on the lens surface.


For extended periods of time, the G2P10 should be stored in a "dry box" environment. This entails the use of a desiccant or heat source to prevent humidity from leaching the lens material. For short-term storage (less than a month), the plastic box and foam packing in which the lens is shipped will provide adequate storage, provided the lens is placed securely in the built-in slot to avoid chipping or scratching from other lenses.

Posted Comments:
tgeorges  (posted 2018-10-11 09:55:44.97)
Would it be possible to have a coating for 450nm wavelength?
YLohia  (posted 2018-10-11 09:39:39.0)
Hello, thank you for contacting Thorlabs. I will reach out to you directly to discuss the possibility of offering a custom version of this.
kyrollosyanny  (posted 2018-08-26 22:16:17.03)
This lens will be a lot more useful if it was infinity corrected. Many people in the field of neuroscience use headmonted microscopes (, having a 1.8 or 2mm diameter infinity corrected GRIN is very useful in that regard and it is an area with huge demand
YLohia  (posted 2018-08-28 11:32:23.0)
Hello, thank you for your feedback. I have posted this new product idea on our internal engineering forum for further consideration.
mlippert  (posted 2018-07-14 11:56:13.65)
I can only reinforce dennis' opinion. This is exactly what the field needs! People are looking for lenses to image mouse hippocampus, cortex with attached 1 mm microprisms as well as various deep brain structures (in our case mouse VTA), so various lengths and thicknesses would be ideal (thickness 1mm and 2 mm for short lenses, 0.5 mm and 0.3 mm for long (ca. 5-7mm lenses)), focal distance in tissue desn't need to exceed 150 um. A company with "opix" in its name has cornered everybody not using their system by supposedly blocking the release of the Grintech lenses to non-customers (at least its hard to get them). There is widespread discontent in the community regarding these business practices which many consider unethical. Gofoton is apparently looking at making equivalent lenses, but regardless of manufacturer, it would be amazing to have an independent manufacturer of imaging lenses for the purpose. If you have any candidate lenses, we would always be willing to test them in our lab with one of our systems.
YLohia  (posted 2018-07-19 09:50:21.0)
Hello, thank you for your valuable feedback. I have posted this idea on our internal engineering forum for further consideration.
dennis.kaetzel  (posted 2017-09-17 21:27:24.387)
Dear Thorlabs, it would be fantastic, if you could offer a range of imaging GRIN lenses that are for chronic implantation (uncoated) and permissive to blue exctitation light as required for MOST applications of those lenses for imaging in life rodents (single-photon, implanted miniscopes). There is only one supplier (GRINtech) of GRIN lenses with a 4th order index of refraction profile, i.e. of high quality ... and that supplier does not sell those lenses for imaging application due to a contract with Inscopics. At the same time, the demand for this technology is surging dramatically as dozens, if not hundreds of labs are starting to use the Miniscope Technology. What would be required are lenses with 0.25 pitch (for the cope) and uncoated lenses with 0.4 pitch and 0.5mm Working Distance and a diameter of 1mm and 0.5 or 0.6mm. You can contact me for more info.
tfrisch  (posted 2017-10-05 12:01:31.0)
Hello, thank you for contacting Thorlabs. GRIN lenses for single photon and water immersion are a part of an open discussion we have internally. I will reach out to you with more details on what you'd be looking for in the future.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
G2P10 Support Documentation
G2P10Customer Inspired! GRIN Lens for Imaging, Ø1 mm, L = 3.4 mm, WD = 0.25 mm (Water), NA = 0.5, ARC: 500-1000 nm
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