Thorlabs PMMA Microlens Arrays (MLAs) are available mounted or unmounted. MLAs are excellent for homogenizing and shaping light, yielding a flat top profile output or square spot patterns. PMMA has excellent UV resistance, filtering out UV light less than 300 nm. The microlenses have a plano-convex shape and are arranged in a 10.0 mm by 9.8 mm rectangular grid with a lens pitch of 1.0 mm by 1.4 mm. These can be used in fly's eye homogenizers, where a round beam is transformed into a rectangular spot (see below for details).

Features:

  • Polymethyl Methacrylate (PMMA) Substrate
  • 10.0 mm x 9.8 mm High-Quality Microlens Array
  • Available Unmounted or in a Ø1" Mount
  • Offered Uncoated or Broadband AR Coated
    • 420 - 700 nm with an AR Coating
    • 650 - 1050 nm with an AR Coating
  • Rectangular Grid Arrangement of Microlenses
  • Arrays with 1.0 mm x 1.4 mm Lenslet Pitches
  • 2.7 mm Single Lens Radius
  • Ideal for Producing a Square Spot with a Flat Top Profile

For the mounted versions, the MLA is glued into a Ø1", 4.0 mm thick mount that is externally SM1-threaded (1.035"-40). The aperture of the lens window is 9.0 mm by 9.0 mm. The plate has slots that are compatible with a SPW602SPW606SPW801, or SPW909 spanner wrench. Their unmounted counterparts are most easily held using one of our cylindrical lens mounts, which are specifically designed to hold square or rectangular optics.

AR Coating Options
While our uncoated PMMA microlens arrays offer excellent performance, improved transmission can be gained by choosing a lens with an antireflective coating on both sides to reduce the surface reflections. Our broadband antireflection (BBAR) coatings provide <0.8% average reflectance over one of the following wavelength ranges: 420 - 700 nm or 650 - 1050 nm.

For microlens arrays that are ideal for use in custom-built Shack-Hartmann wavefront sensors, please visit the Fused Silica Microlens Arrays page.

Fly's Eye Homogenizer

There are multiple ways to homogenize the output of a light source. Microlens arrays (MLAs) used in a fly's eye homogenizer configuration transforms a round collimated beam with a Gaussian profile into a rectangular homogeneous spot. The size of the rectangular spot is defined by the size and pitch of the microlenses.

The application photo above shows the configuration mounted in a 30 mm cage system. The light source is a PL201 compact laser module fixed in an AD11F SM1-threaded adapter held in a CP33(/M) cage plate. Alternatively, a multimode fiber fed with a fiber-coupled LED can be connected to a collimator such as the F240SMA-A. Doing this will get rid of the speckles produced by the laser. The light passes through the first of two MLAs held in CP6T cage plates. These cage plates are thin enough to hold the mounted MLAs. The lensed side of the MLAs should be facing the source. It is key to accurately align the MLAs to each other; there will be artifacts on the screen otherwise. The light then passes through an LB1471 N-BK7 bi-convex lens to produce a rectangular 9 mm x 12 mm spot on an EDU-VS2(/M) screen, as seen in the photo to the right.

Please note that this is a spot and not a beam, meaning the spot is sharply defined only at a certain distance from the focusing lens. The actual size of the spot can be adjusted by changing the distance between the two MLAs. Decreasing the distance will increase the size of the rectangle and increasing the distance will make the spot smaller. Different uncoated bi-convex lenses, such as the LB1092 Ø1/2" lens with 15.0 mm focal length or LB1014 Ø1/2" lens with 25.0 mm focal length, can also be used to produce a smaller rectangular spot. A setup like this can be mounted directly on a post. Post holders with clamping forks secure the setup to a breadboard such as the MB3045(/M). A simplified diagram of the setup is shown below.