An exact science

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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.

Some of the latest positioning solutions for photonics equipment on the market

Positioning 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 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

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.

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 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 (see lead image) 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 for its small size thanks to the integration of compact piezo stages, high-quality joints, and low friction mechanical parts. Its closed loop control with linear optical encoders enables it to reach the highest precision performances. The NanoPos has a travel range of ±5mm/±10°, a resolution of 10nm/1µrad, a repeatability of ±38nm / ± 1µrad and a payload of 500g.

To meet maximum payload and form factor requirements for use as a single-axis positioner, as part of an integrated system or even an integrated machine, Aerotech’s ABRX air-bearing rotary stages are available in diameters of 100, 150 and 250mm. This makes them particularly suitable for exacting requirements in wafer inspection, high-precision metrology, optical inspection and manufacturing, and MEMS/nanotechnology device production. These rotary tables are directly driven and can achieve rotational speeds of up to 300rpm. Another special feature is the air bearing design, which minimises radial and axial errors, which are typically in the range of less than 25nm. This series is particularly suitable for high-precision test and inspection systems and surface measurement applications, including the measurement of roundness, flatness, form errors or other measured variables of profilometry.

Physik Instrumente’s V-817 high load linear stage series offers high price-to-performance in positioning solutions for highly dynamic and precise processing, testing, and inspection tasks in the semiconductor, electronics, and laser industries. The stage is suitable for applications such as sensor and camera positioning, laser welding, optical and tactile testing procedures, as well as wafer processing and inspection. These stages are designed for industrial applications with high operating cycles: three-phase linear motors with recirculating ball-bearing guides offer constant loads up to 600N and velocities up to 3,000mm/s. In addition, the incremental linear encoder offers a resolution down to 0.3nm, ensuring high path accuracy, minimum tracking errors, and short settling times. The calibrated positioning accuracy of the linear stages is up to ±2.5µm. The travel range extends to 813mm.

The M3 family of micro-stages and actuators from New Scale Technologies are all-in-one ‘smart modules’ with built-in controllers: easy to integrate into handheld and portable instruments. They enable smaller, smarter imaging systems, scientific instruments, medical devices, aerospace and defence systems, and more. The fully embedded driver electronics allow the devices to be truly miniaturised. Adding further to its compactness are the patented Squiggle and UTAF piezoelectric micro motors. These systems are ideal for compact and portable photonics systems requiring precision motion control.

The new MiniSlide MSA series of linear actuators from Haydon Kerk Pittman offers design flexibility with two motor options: a 21mm, size 8 hybrid linear actuator, and a 20mm, 19000 series can stack linear actuator. In addition, there are nine different lead screw options ranging from ~0.3 to 8mm – providing resolution down to 0.001524mm per step, axial forces up to 45N and accommodating stroke lengths of up to 150mm. Finally, four different lubrication options, a rotary encoder feedback option, as well as English or metric mounting hardware standards are available. The MiniSlide series provides pre-engineered versatility for a variety of single and multi-axis applications. By providing a compact, cost-effective and highly-customisable linear motion solution, the MSA is ideally suited for use in lab equipment applications such as sample handling, spectrometers and chromatographers, molecular analysers, optical microscopes and other inspection equipment.

Moticont’s DDLM-019-044-01 non-commutated linear actuator is zero cogging and fully enclosed. It is just 19.1mm in diameter and has a housing length of 44.5mm and a stroke of 11.7mm. This linear actuator can develop 3.1N of continuous force and 9.7N peak force. Direct coupling of the actuator to the load results in zero backlash and allows for acceleration/deceleration, and high-speed positioning. Controllable force, stroke length and speed, and maintenance free, the DDLM-019-044-01 can be used with a position sensor and controller for the repeatability and accuracy of a closed loop application. It can be used for applications such as positioning, assembly, sorting, sampling, valve actuation, reagent dispensing or life support.

For applications such as vibration excitation or motion control, the acceleration induced by a piezo actuator is an indispensable measurement and control variable. Piezosystem Jena has therefore developed a new acceleration sensor for high-power actuators that enables this essential quantity to be detected. The compact, miniature size acceleration sensor provides an analogue output voltage proportional to the acceleration, which is then detected by the corresponding signal amplifier from where it can be further processed. This sensor has a measurement range of ± 750g a frequency range of 1Hz to 25kHz, and an output voltage of ±10V. Its applications include modal analysis, vibration control, material testing and mechanical engineering.



Featured product: Nanomotion FB-Series Piezoelectric Motion Stages from Pro-Lite Technology

The Nanomotion FB Series of motion control stages provides linear, rotary or vertical motion with nanometric precision. Based on a proprietary, standing-wave piezoelectric technology, Nanomotion motors and motion systems are suitable for a diversified range of applications where precise, nanometric control is required.

In photonics motion control applications, how do you combine speed with nanometric precision and unlimited travel? These seemingly conflicting requirements are uniquely addressed by ultrasonic, standing-wave, direct-drive piezoelectric motors. This technology provides unlimited linear or rotary motion of a ceramic tip that transfers drive to a target, operating in a manner similar to a DC servo motor but with much higher resolution, an order-of-magnitude higher speed and a wider dynamic range.

The Nanomotion FB Series of stages provides single or multi-axis motion performance for a wide range of applications in optical alignment in the semiconductor, biomedical, and analytical instrumentation markets.

Find out more at: Nanomotion Piezoelectric Motors & Motion Systems


Featured product: Position Sensitive Detectors from Laser Components

Position sensitive detectors (PSDs) offer high accuracy (~2.5µm), excellent resolution and short rise times as fast as 30ns for non-contact alignment, position measurement/detection and machine vision applications.

SiTek’s PSDs are available in wavelengths from 400-1100nm with a variety of options including one dimensional (single axis), two dimensional (two axis), specialist 3D arrays for contour measurement, UV, YAG and nuclear sensors.

Application examples include railway bow measurement for fault detection, vibration monitoring, 3D contour measurements, bridge and tower construction, shaft alignment, robotic guidance, and a variety of machine vision applications.

These PSDs can be used with the SEEPOS PSD processing tool to interface with your PSD and connect directly to your computer, complete with a LabVIEW compatible software package and data analysis suite.  The SEEPOS system offers a plug and play style system with real time display including analogue and digital features.

Used with the PSD/SEEPOS switch, the operator can easily switch between one to four PSDs.