Polymer Engineered Diffusers®

Features

• Ø1" Diffusers
• ZEONOR Polymer Substrate
• Homogenize Input Illumination
• Circle, Square, or Line Patterns
• High Transmission Efficiency
• Achromatic Performance
• Available Unmounted or Mounted
• Ideal for Low-Power Applications

Thorlabs offers Polymer Engineered Diffusers^®*, which provide non-Gaussian intensity distributions in square, circular, and line distribution patterns. The square and circular patterns are offered in 20° and 50° divergence angle options, while the line distribution has a 0.4° x 100° divergence; typical diffusers do not offer this advanced level of light control. 

These cost-effective Engineered Diffusers are made from injection molded ZEONOR polymer and have 90% transmission efficiency from 380 nm - 1100 nm. They are ideal for low-power applications and are designed for use with Ø0.5 mm or larger laser beams; smaller beams should be expanded prior to the diffuser. For high-power applications or applications requiring UV transmission, Thorlabs offers UV Fused Silica Engineered Diffusers. 

Our Polymer Engineered Diffusers are available unmounted or mounted. The mounted Ø1" diffusers come in an engraved SM1-threaded (1.035"-40) mount, as shown at the top of the webpage. The mount provides quick identification and helps protect the diffusers from fingerprints and other contamination. SM1 threading is particularly useful when building Ø1" lens tube and 30 mm cage systems. These mounted diffusers are available individually or as a set of all five in a labeled storage box.

Please see the Technology tab for more information on the technology and fabrication of our Engineered Diffusers.

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

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SEM Picture of Engineered Diffuser for Display Brightness Enhancement

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SEM Picture of Engineered Diffuser for Projection Screens

Engineered Diffuser^® Technology
Thorlabs' Engineered Diffusers provide advanced beam shaping that leads to significant performance enhancements for applications as diverse as lithographic systems, outdoor lighting, displays, backlighting, display brightness enhancement, and projection screens.

Homogeneous diffusers made of, for example, ground glass, opal glass, or holographic elements, consist of repeating, uniform surface patterns across the entire clear aperture that provide only limited control over the shape and intensity profile of the illuminated area, causing the incident light to be used inefficiently. In addition, holographic diffusers are usually limited to monochromatic applications using coherent light. On the other hand, Engineered Diffusers consist of differing, individually manipulated microlens units that provide broadband compatibility and excellent control over the light distribution and beam profile.

Each microlens unit that forms the diffuser is individually specified with respect to its surface profile and location in the array. At the same time, to ensure that the diffuser is stable against variations in the input beam's intensity profile and usable in the visible and IR, the distribution of microlenses is randomized according to probability distribution functions chosen to implement the desired beam shaping functions. The microlens distribution also removes zero-order bright spots and diffraction artifacts from the output. In this manner, Engineered Diffusers retain the best properties of both random and deterministic diffusers.

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Diagram of Mastering Process

Fabrication
The master microlens array is produced by a laser writing system developed by VIAVI Solutions, Inc. This system exposes a thick layer of photoresist point-by-point in a raster scan mode, as shown to the left. By modulating the intensity of the laser beam as it is scanned, the degree to which the photoresist is exposed can be varied. A deeply textured, engineered surface is the result, as shown above in the two SEM images of the surface topography.

Introduction
These Polymer Engineered Diffusers^® are designed to create non-Gaussian intensity distributions in circular or square beam profiles that diverge from the plane of incidence. Below, to the left of the page, are the theoretical approximations of the intensity through the center of the diverging beam profile when illuminating the engineered diffusers with a 633 nm collimated beam. To the right are data compiled from independent tests with laser wavelengths of 488 nm, 637 nm, 785 nm, and 1064 nm to demonstrate the change in output profile with wavelength. The highlighted region of each graph denotes the divergence angle of the engineered diffuser. At the bottom of this tab is a description of the laboratory setup and procedure used to collect these data and the results.

Circular Pattern Diffusers Transmitted Intensity Plots

Click to Enlarge Theoretical Data for ED1-C20	Click to Enlarge Experimental Data for ED1-C20 Raw Data
Click to Enlarge Theoretical Data for ED1-C50	Click to Enlarge Experimental Data for ED1-C50 Raw Data

Square Pattern Diffusers Transmitted Intensity Plots

Click to Enlarge Theoretical Data for ED1-S20	Click to Enlarge Experimental Data for ED1-S20 Raw Data
Click to Enlarge Theoretical Data for ED1-S50	Click to Enlarge Experimental Data for ED1-S50 Raw Data

Line Pattern Diffuser Transmitted Intensity Plot

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Theoretical Data for ED1-L4100

Experimental Set Up
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[APPLIST]

[APPLIST]

Note: A previous-generation NR360S^a Rotation Mount was used in the above experimental set-up. High Performance Black Masking Tape was used to cover metal which might reflect laser light. A MFF101 Motorized Flipper with an empty LMR05 is not being used. 

Light Preparation
Wavelength (nm)	488	637	785	1064
Source	LP488-SF20	LP637-SF70	LP785-SF100	DBR1064S
Heat Sink	LDM9LP			LM14S2
Collimator	TC06FC-543	TC06FC-633	TC06APC-780	TC06APC-1064

Procedure
Four wavelengths of light were chosen for study: 488 nm, 637 nm, 785 nm, and 1064 nm. These were prepared using the equipment to the right (a full list of all parts used can be found under the photo of the Experimental Set Up). The optical path was approximately 35 cm above the surface of the breadboard; it began when fiber-coupled light sources were collimated with triplet collimators, using a design wavelength as close to the source wavelength as possible. In free space, the beams were incident upon one of the Polymer Engineered Diffusers. The exiting divergent profile was isolated and focused by an LA1304 plano-convex lens attached to an SM05L20 lens tube. The signal was sampled every 0.5° by a SM05PD1A photodiode. This assembly was mounted on the end of an XT34-500 rail. The opposite end of the rail was mounted to a previous-generation NR360S^a rotation stage centered with the engineered diffuser under test in order to sweep the detector and lens assembly through the center of the profile, as illustrated below, and plot normalized intensity versus output angle. The distance between the diffuser and the detector was approximately 43 cm. The output angle was defined with respect to the original optical axis when the diffuser was not within the path. In order to control for ambient light, a 1 kHz sine wave was used to modulate the drive current applied to the laser diode and the signal was acquired with a lock-in amplifier. A LabVIEW program was written to control the setup and acquire the data.

Experimental Limitations
Only one of each Item # was tested^b. Stability may have been compromised by the experiment being performed on a PBG11113^c breadboard without any isolation. Only the middle of each diffuse shape was measured, so variances in other areas of the shape are possible, including the corners of the square profiles.

Results
It was found that there was little variance in diffuse beam profile with respect to wavelength across the middle of each beam profile. Above, to the left of the page, are the theoretical estimations of intensity across the width of the resulting beam profile. To the right of the page are data compiled from independent tests with various laser wavelengths to verify the theoretical models.

• This is a previous generation item. Please see HDR50 for an up-to-date replacement.
• The ED1-L4100 was not tested.
• This is a previous generation item. Please see the PBG3648F (PBG90120A) for an up-to-date replacement.

	Item #	Theoretical	Experimental	Raw Data
Circular Patterns	ED1-C20			Click Here
	ED1-C50			Click Here
Square Patterns	ED1-S20			Click Here
	ED1-S50			Click Here
Line Pattern	ED1-L4100		Not Available	Not Available

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