Unmounted N-BK7 Ground Glass Diffusers
- Offered in 120, 220, 600, and 1500 Grit Polishes
- Polished for Greater Uniformity than Sand Blasting
- Round and Square Diffusers
(100 mm x 100 mm)
- Available in Four Sizes:
- Round: Ø1/2", Ø1", and Ø2"
- Square: 100 mm x 100 mm
- Substrate Material: N-BK7 (Uncoated)
Thorlabs' Unmounted N-BK7 Ground Glass Diffusers provide a solution for a variety of applications requiring a diffuse Gaussian-like distribution. They are offered in 120, 220, 600, and 1500 grit polishes. Each grit polish is available in Ø1/2", Ø1", and Ø2" round versions as well as a 100 mm x 100 mm square.
For improved transmission, our Ø1" diffusers are also available with an AR coating for either 350 - 700 nm or 650 - 1050 nm. When positioning the diffusers, the grit-polished side should face away from the source.
Polished diffusers are advantageous over sand blasted diffusers, as their surfaces have greater uniformity. The various grits provide a range from fine to coarse scattering. A finer grit (e.g. 1500) has a small diffusion pattern, while a coarser grit (e.g. 120) will have a larger diffuser pattern. See the plot below to compare the performance of our diffusers. See the Graphs tab to see individual graphs for each grit polish level, as well as measurement details.
Please see the Application Idea tab for a Diffused LED Condenser that uses a ground glass diffuser. For applications requiring specific divergence angles, spatial distribution of the illumination, and intensity profiles, our engineered diffusers are more suitable. Thorlabs also offers UV Fused Silica Diffusers for applications that extend into the ultraviolet portion of the spectrum.
|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|
|Surface Flatness of Smooth Side (@ 633 nm)||<4λ|
|Surface Quality of Smooth Side||80-50 Scratch-Dig|
|DG100X100-120||100 mm x 100 mm||120|
|DG100X100-220||100 mm x 100 mm||220|
|DG100X100-600||100 mm x 100 mm||600|
|DG100X100-1500||100 mm x 100 mm||1500|
Please note that the transmission values are affected by the manner in which the data is collected. An integrating sphere is used along with a spectrometer, and as the grit values get smaller the light is more dispersed, making it difficult to collect all of the light into the spectrometer. Therefore, lower grit values will appear to have a lower transmission.
Bidirectional Scattering Distribution Function Graphs
This data was taken by directing a HeNe laser at a diffuser and collecting the light with a receiver that was rotated around the diffuser to measure the angle-resolved scatter (ARS). The bidirectional scattering distribution function (BSDF), which is found by dividing the ARS by the cosine of the angle between the input beam and the receiver, measures the amount of scattering that occurs after light permeates the diffuser. The X axis of these graphs is the angle at which the scatter is occurring. This is why at 0° there can be a spike; this spike is representative of the specular beam going through the diffuser.
Build Your Own Collimated LED Source
The setup shown to the lower right uses a DG20-600, Ø2", 600 Grit Ground Glass Diffuser as part of a homemade Diffused LED Condenser, which collimates the light exiting the LED source. Although Thorlabs also manufactures out-of-the-box collimated LED light sources, which essentially provide the same result, the one shown here is perfect for those inclined to build their own, perhaps as part of an educational setup. In this particular case, the setup was built using a 60 mm cage system. If you are not familiar with Thorlabs' 60 mm cage assemblies, they consist of cage-compatible components that are interconnected with cage rods. Each cage component features four tapped holes with center-to-center spacings of 60 mm, and they are joined together into a cage system using Ø6 mm rigid steel cage rods; in this case, 4" long cage assembly rods were chosen. The reason for building a cage system is to ensure that the optical components housed inside the cage system have a common optical axis.
To integrate the MWWHL4 Warm White Mounted LED, which has internal SM1 (1.035"-40) threading, into the 60 mm cage system, the mounted LED was threaded into an LCP02 30 mm-to-60 mm cage plate adapter using an SM1T2 Lens Tube Coupler. Next, the light source is directed through a Ø2", 600 grit ground glass diffuser, which is held in place by two SM2RR Retaining Rings on an LCP34 60 mm Cage Plate. After exiting the diffuser, the divergent light is collimated using an LA1401 Plano Convex Lens with a focal length of 60.0 mm. The lens is also housed in an LCP34 60 mm Cage Plate.
The entire 60 mm cage assembly is mounted onto a TR3 post using the 8-32 thread on the bottom of the LCP34, placed in a PH3 post holder, and attached to the breadboard using a BA2 Mounting base.
The tables below correspond to either the imperial or metric list of components needed to build a Diffused LED Condenser.