TECH FOCUS POSITIONING EQUIPMENT
An exact science
Some of the latest positioning solutions for photonics equipment on the market
P
ositioning equipment plays a vital role in ensuring high resolution,
repeatable motion and fixturing across numerous photonics applications in both research and industry. Such equipment encompasses everything from linear stages, rotational stages and hexapods to actuators, motion controllers and drivers. For example, the equipment is crucial in any application involving laser technology. Laser beam positioning and steering requires extreme precision, dynamics and reliability, which can be achieved through the accurate manipulation of lenses and mirrors. Positioning equipment, such as piezo drivers, are used for parallel-kinematic positioning in compact tip/ tilt mirror systems and piezo- based scanning platforms, which are used, for example, to manipulate beams during the production of electronics. Positioning equipment also
plays a crucial role in the manufacture of aspherical lenses, which are used to achieve high image quality in optical systems using fewer optical elements, while providing savings in both cost and weight. Testing the aspheric shape accuracy of such lenses is a considerable
36 Electro Optics March 2021
challenge, however, and requires measuring the tiniest deviations in the nanometre range using interferometry. Here, hexapods can be used to manipulate the lenses in carrying out several positioning tasks during calibration and measurement. Other application examples of positioning equipment include: microscopy, in which linear and rotary stages are used to rotate and lift the samples; silicon photonics fabrication, in which delicate waveguides must be handled with great precision when integrating light sources at a wafer level, and in which optical fibres must be aligned and connected; and in the positioning of optical elements when assembling complex optical systems, such as objective lenses for smartphone cameras or laser cavities. The scope of application
for photonics positioning equipment ranges from manipulating waveguides on a wafer level to manipulating some of the largest optics in existence. For example, the European Extremely Large telescope features 798 individual 1.4m-diameter, 250kg mirror segments. Each of these must be moved at velocities between several nanometres per second to +/-0.45µm/s, and with an average position deviation of less than 2nm when tracking an object through the sky during observation. Thanks to modern advances in photonics positioning equipment, this incredible feat of engineering is now possible.
Commercial products
The HXP100-MECA high-
precision six-axis hexapod from MKS Instruments has a 20kg centered load capacity and is an effective solution to complex motion applications that demand high load capacity and accuracy in up to six independent axes. Its travel range in the X, Y, and Z axes is ±27.5, ±25 and ±14mm respectively. Roll, pitch, and yaw (ΘX, ΘY and ΘZ) are ±11.5, ±10.5 and ±19°. Maximum velocity in the X, Y, and Z axes are 2.5, 2 and
Alio Industries’ Angulares Hybrid Hexapod offers 60° tip/ tilt travel, which, according to the firm, is the most angular travel range available from any six-degree-of-freedom positioner on the market. The hexapod features precision crossed roller bearing guides, optical incremental or absolute encoder feedback on all axes, linear motor and/or servo ball screw drives, unlimited programmable tool centre point locations and co-ordinate offsets, and zero backlash on all axes.
The design makes the Angulares capable of unlimited XY travel, Z travel for 62mm, which can be increased to 208mm using other tripod models, tip/tilt travel of 60° (+/-30°) with continuous 360° theta-Z, XYZ bidirectional repeatability of less than +/- 0.6 arc-seconds, velocity up to 100mm/s in XY and Z, and less than 10nm linear and 0.1 arc-seconds angular minimum incremental motion.
1mm/s, and 1.8, 1.7 and 3°/s for ΘX, ΘY and ΘZ. Minimum incremental motion in the X, Y and Z axes is 0.5, 0.5 and 0.25µm and in ΘX, ΘY, ΘZ are 0.25, 0.25, 0.5mdeg. This device is suitable for applications in interferometry, diffractometry, optics positioning, optical fibre or device alignment, imaging and microscopy.
Symetrie’s NanoPos is a miniature hexapod of 68mm height for positioning and adjustment of precision components in six degrees of freedom, with a 10nm resolution. NanoPos comes with excellent characteristics
@electrooptics |
www.electrooptics.com
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