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
Collimated Light from a HNL050LB HeNe Laser
|Diffuser Selection Guide|
|Ground Glass Diffusers|
|Standard Diffusers||N-BK7 Substrate||Unmounted, Uncoated||350 nm to 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|
- 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.
|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)
|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|
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.
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.