N-BK7 Diffuse Reflectors, Protected Silver Coating

  • Highly Diffusive Over Broadband Range from 450 nm to 20 µm
  • Polished for Greater Uniformity than Sand Blasting
  • Offered in 120, 220, 600, or 1500 Grit Polishes


120 Grit


220 Grit


600 Grit

DG10-1500-P01 Reflecting
Collimated Light from a HNL050LB HeNe Laser

Related Items

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Diffuser Selection Guide
Ground Glass Diffusers
Standard Diffusers N-BK7 Substrate Unmounted, Uncoated 350 nm - 2.0 μm
Unmounted, AR Coated 350 nm - 700 nm
650 nm - 1050 nm
Mounted, Uncoated 350 nm - 2.0 µm
UVFS Substrate Unmounted, Uncoated 185 nm - 2.0 µm
Diffuse Reflectors N-BK7 Substrate Unmounted, UV-Enhanced Aluminum Coated 250 nm - 450 nm
Unmounted, Protected Silver Coated 450 nm - 20 µm
Unmounted, Protected Gold Coated 800 nm - 20 µm
Alignment Disks
Engineered Diffusers®*
Glass Diffusers UVFS Substrate Unmounted and Mounted, Uncoated 193 nm to 2.0 µm
Polymer Diffusers ZEONOR Substrate Unmounted and Mounted, Uncoated 380 nm to 1.1 µm
Diffuser Kits

*Engineered Diffusers® is a registered trademark of VIAVI Solutions, Inc.

Optical Coatings and Substrates


  • Ø1" Diffuse Reflectors
  • Coated Surface has 120, 220, 600, or 1500 Grit
  • Protected Silver HR Coating for the 450 nm to 20 µm Range
  • Clear Aperture: >90% Diameter
  • Near-Gaussian Intensity Pattern at Small Angles of Incidence (AOIs) (See Graph Below)
  • N-BK7 Substrate

Thorlabs' Diffuse Reflectors are a solution for applications requiring a diffuse intensity pattern. Our diffuse reflectors are produced from an N-BK7 substrate with a protected silver coating applied to the ground side of the optic and are available in 120, 220, 600, and 1500 grit polishes. Though the overcoat helps to protect silver from tarnishing, high humidity environments should be avoided.

Polished diffusers are advantageous over sand blasted diffusers as the surface has greater uniformity. The various grits provide a range of reflected intensity distributions. A coarser grind (e.g., 120) creates a wider diffusion pattern, while a finer grind (e.g., 1500) will provide a more localized one. The distribution of reflected light (AOI = 0°) for each diffuser is shown in the graph below. To see how the distribution changes for AOIs of 15°, 30°, and 45°, see the Graphs tab. This sample data is typical and results may vary.

These diffuse reflectors have a thickness of 2.0 mm and thus are too thin to be used in our standard mirror mounts. Mounting options include our LMR1 Fixed Mount for Ø1" Optics, Ø1" lens tubes, or the KM100T Threaded Kinematic Mount. When mounting a diffuse reflector in a threaded optic mount, such as the LMR1, the ground and coated surface should face the lip of the mount and the retaining ring should secure the uncoated side, as shown in the image on the bottom right. If the diffuse reflector is mounted facing the opposite direction, the reflective face will be recessed inside the mount and the housing will block a portion of the diffusely reflected light.

Click to Enlarge

Mount the optic with the input face towards the back of the LMR1 to prevent the obstruction of reflected beams.

Click to Enlarge

Click Here for Raw Data
This typical data was taken with a light source at a 0° AOI. The curves are normalized to the peak measured value for the 1500 grit diffuser to highlight the differences in peak shape and intensity distribution between diffusers.
Common Specifications
Coating on Grit Side Protected Silver
Average Reflectance of Coating
(AOI = 0 to 45°)
>97% (450 nm to 2 µm)
>95% (2 µm to 20 µm)
Substrate N-BK7
Diameter 1" (25.4 mm)
Diameter Tolerance +0.00/-0.25 mm (+0.00"/-0.01")
Thickness 2.0 mm (0.079")
Thickness Tolerance ±0.2 mm (0.008")
Clear Aperture >90% Diameter
Parallelism <3 arcmin
Item # Grit
DG10-120-P01 120
DG10-220-P01 220
DG10-600-P01 600
DG10-1500-P01 1500

Below are the reflectance curves for the protected silver coating for S-polarized, P-polarized, and unpolarized light. The shaded region of the graph denotes the wavelength range over which we recommend using these diffuse reflectors. A link to download the raw data is available below the graph.

Reflectance of 120 Grit Diffusers
Click to Enlarge

Click Here for Raw Data


For each grit available on this page, we have provided data showing the reflected intensity distribution for four AOIs. Intensity distributions were measured with a collimated source at a 0°, 15°, 30°, or 45° AOI. The gap in each curve represents the AOI of the light source. The intensity measurements were normalized by setting the peak measured value for the 1500 grit diffuser with the source at a 0° AOI equal to 1.

Intensity Distributions for 120 Grit Diffusers
Click to Enlarge

Click Here for Raw Data
Intensity Distributions for 220 Grit Diffusers
Click to Enlarge

Click Here for Raw Data
Intensity Distributions for 600 Grit Diffusers
Click to Enlarge

Click Here for Raw Data
Intensity Distributions for 1500 Grit Diffusers
Click to Enlarge

Click Here for Raw Data

Posted Comments:
Jonathan Cohen  (posted 2024-03-19 07:16:32.93)
Would you please tell me the thickness of the Ag coating on the DG10-600-P01 ground glass diffusers. We would like to etch a pattern on the surface and need to know the thickness. thanks, jc
jdelia  (posted 2024-03-19 01:15:59.0)
Thank you for contacting Thorlabs. We unfortunately cannot share this information as our coating thicknesses are proprietary. We apologize for the inconvenience. I have contacted you directly to discuss your application.
user  (posted 2024-02-09 10:49:16.46)
Is the damage threshold comparable to a similarly coated mirror or better/worse?
cdolbashian  (posted 2024-02-16 03:27:38.0)
Thank you for reaching out to us with this inquiry. We would expect the damage threshold to be lower, due to the fact that these surfaces are not polished for optimum reflection. There could be localized heating due to surface/sputtering imperfections. I have contacted you directly to address these concerns.
cbrideau  (posted 2013-04-01 13:20:04.197)
I am working on an application where I need good diffuse reflection of 400 to 700nm. I notice the silver coating rolls off at ~450, but could you do this with aluminum or UV-enhanced aluminum? If you could this would be perfect for my application.
jlow  (posted 2013-04-01 15:34:00.0)
Response from Jeremy at Thorlabs: We could do this with UV-enhanced aluminum. I will get in contact with you regarding the quote for this.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
DG10-120-P01 Support Documentation
DG10-120-P01Customer Inspired! Ø1" Prot. Silver Reflective Ground Glass Diffuser, 120 Grit
DG10-220-P01 Support Documentation
DG10-220-P01Customer Inspired! Ø1" Prot. Silver Reflective Ground Glass Diffuser, 220 Grit
DG10-600-P01 Support Documentation
DG10-600-P01Customer Inspired! Ø1" Prot. Silver Reflective Ground Glass Diffuser, 600 Grit
DG10-1500-P01 Support Documentation
DG10-1500-P01Customer Inspired! Ø1" Prot. Silver Reflective Ground Glass Diffuser, 1500 Grit