Microlens Array

21 Mar 2022

Overview

Microlens arrays are rigid arrangements of very tiny lenses, each with a diameter of less than 10 millimeters. These arrays may be one or two dimensional, and are mounted in a regular pattern on a supporting substrate. The microlenses themselves may be circular, square, or hexagonal, and the array may be square, hexagonal, or some other geometric shape.  Microlens arrays are used in optical microscopes and light fields cameras, on CCD arrays, and for 3D imaging and displays, fiber coupling, optical sensors and LIDAR systems.

At Shanghai optics we produce both 1- and 2- dimensional arrays, in a variety of different configurations, sizes, and focal lengths. These arrays are manufactured from high quality fused silica, and optimal performance range is from 193 nm to 2.5 micrometers.  The index of refraction of these arrays are 1.561 at 248 nm, and 1.444 at 1550 nm.

Photolightographic techniques and semiconductor processing technology allow us to produce precisely positioned arrays with very accurate shaping of the lens profile. We can work with you to produce custom microlens arrays according to your specifications, and our experienced design team is able to provide consultation and design help as needed.  Our many years of experience, coupled with state of the art equipment, allow us to produce high quality optics to almost any specification.

Applications of Microlens Arrays

Microlens arrays are the engineering equivalent to natural compound eyes: they provide large field of view angles, high temporal resolution, low aberration and distortion and infinite depth of field. These properties make them an ideal design component in 3D imaging. They can be used, with a variety of light emitters, to homogenize light, and are especially useful for optical applications that require non-Gaussian uniformity and high efficiency.

In a digital projector, microlens arrays can be used to focus light on to the active area of the LCD to generate the image which will be projected. A novel design for a LED pico-projector involves using a special array of 45 microlenses aligned on the display coverglass.  The use of a microlens array in this projector design allows the projector to be highly compact and  robust while still being capable of producing bright, crisp imagery.

Square Microlens Arrays

Square microlens arrays are primarily used for beam homogenization and shaping. Their very high fill factor (up to 98%) essentially eliminates zero order hot spots in the illuminated field. A standard square microlens is 10mm x 10mm configuration, although we can provide custom sizes upon request.  A variety of focal length and lens pitch options are also available.

Fly’s Eye Array

A fly’s eye array consists of individual square or rectangular microlenses mounted on a substrate in a close-packed, no-gaps configuration. A typical array will have 7-11 channels in each direction, optically overlapped in the illumination plane.  The surface of the microlenses may be either anamorphic or spherical.

When a pair of fly’s eye arrays is used in combination with a condenser lens they can provide uniform irradiance at the illumination plane.  When set up in this configuration the first array is called the objective array, and the second the field array.

Factory Standard 

• Diameter: +0, -0.1mm
• Surface accuracy: λ/2 @633nm or better
• Thickness: ±0.2mm
• Centration: ±0.04mm
• Surface quality:20-10
• Bevel: 0.2mm typical
• Material: SK2; BK7 and more

Contact us for manufacturing limit or custom specifications.

To learn more about microlens arrays, click here: https://www.shanghai-optics.com/components/micro-optics/microlens.