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Rotation Mount with Resonant Piezoelectric Motors![]()
ELL14K Rotation Mount Bundle Rotation Mount for Ø1" or Ø25.0 mm Optics Interface Board Application Idea The ELL14K rotates a mounted, SM1-Threaded polarizer within a 60 mm cage assembly. ELLB Bus Distributor Related Items ![]() Please Wait
![]() Click to Enlarge The components of the ELL14K Rotation Mount Bundle are shown connected and with key features labeled. The rotation mount can be adapted for post mounting using SR025 cage rods and the ELLA1 post mounting adapter.
Features
Driven by Thorlabs' Elliptec™ piezoelectric resonant motor technology, this rotation mount is designed to be a compact solution for applications requiring optic rotation. Thorlabs offers the ELL14K rotation mount bundle, which contains the ELL14 rotation mount, an interface board for manual control of the mount, power supply, and cables for connecting the mount and interface board to each other and to a PC. The ELL14 can also be purchased separately. The rotating cell of each mount is internally SM1 (1.035"-40) threaded and includes two SM1RR retaining rings for mounting Ø1" or Ø25.0 mm optics. It is designed to be lightweight and compact, and the closed-loop operation provides rotation to specified orientations with a repeatability of 873 µrad. The assembled components of the ELL14K are shown in the image to the right, with key features labeled. Please see The Elliptec™ Motor tab for more information. The motors are highly dynamic and have no gearing. The tips of both motor housings are in firm contact with the plastic track at the base of mount, as can be seen in the image at the right. The motors are installed with opposite orientations and translation in both directions occurs when one motor pushes the track forward while the other pulls it backward. The rotation mount is not designed for continuous operation. We recommend operation with duty cycles of 40% or less. When power is not applied to the motors, the stage is held in place by an approximately 0.01 N·m combined torque exerted by the stationary arms of the motors. The open frame format, versatility, and simplicity of this rotation mount makes it attractive for OEM applications, as it can be customized according to customer requirements and produced in high-volume quantities. Please contact us to discuss your specific requirements so that we may tailor a solution to meet the needs of your application. Control
Multiple Elliptec devices can be controlled using the ELLB Bus Distributor or by splicing multiple connectors onto one ribbon cable. A single bus distributor can connect up to four Elliptec devices; up to 16 devices can be connected if the buses are daisy chained. This bus can be controlled one of three ways: through an interface board (included with the bundles below) to connect to a PC running the Elliptec software, by connecting to an Arduino®2 or Raspberry Pi®3 board, or by wiring the connector pins to a user-supplied control board. Alternatively, up to 16 devices can be spliced onto a single ribbon cord. The devices can then be simultaneously controlled by the interface board or selectively controlled by the Elliptec software. See the manual for instruction on how to splice multiple devices onto a ribbon cord and the Pin Diagrams tab for pin assignments when making custom connections.
![]() Click to Enlarge Components of the ELL14K Bundle (One Region-Specific Power Adapter Included with the Power Supply) ![]() Click to Enlarge Mechanical Drawing of the Rotation Mount For more information on mounting options see the Operation tab. ![]() Click to Enlarge Mechanical Drawing of the Interface Board
![]() Click to Enlarge Pinout diagram of the Picoflex® connector is shown referended to a partial diagram of the ELL14 Rotation Mount Board.
![]() Click to Enlarge Pinout diagram of the Picoflex® connector is shown referenced to a simplified diagram of the ELLB Bus Distributor. The polarity indicator on the connector must be adjacent to the red wire on the supplied 8-connector cables. Operation NotesThis tab contains information on handling, mounting, and operating the ELL14K Rotation Mount Bundle. Contents
![]() Click to Enlarge The Rotation Mount, Back ![]() Click to Enlarge The Rotation Mount, Front HandlingThe rotation mount and interface board included in the ELL14K bundle are robust to general handling. To ensure reliable operation, keep the surface of the plastic track contacted by the motors free of oils, dirt, and dust. It is not necessary to wear gloves while handling the rotation mount, but avoid touching the track to keep it free of oils from fingerprints. If it is necessary to clean the track, it may be wiped with isopropyl alcohol or mineral spirits (white spirit). Do not use acetone, as this solvent will damage the plastic track. The open frame format of the ELL14 can tolerate up to 8 kV of static discharge. ESD precautions should be taken, as an electrostatic discharge can produce an electrical signal that may cause an unintended movement of the mount. A bending load in excess of 500 g applied to the board may cause the PCB to deform, which will degrade the performance of the rotation mount. As readings from a magnetic sensor are used during the homing and positioning of the mount, avoid subjecting the structural PCB to excessive loads or magnetic fields. Limit the strength of magnetic fields in proximity to the magnetic sensor to ±5 mT to avoid negatively affecting the homing and positioning operations. Mounting and Loading the Rotation MountThe rotation mount may be mounted either vertically or horizontally. The Elliptec motors should be facing up if the mount is used horizontally. The mount has several mounting features that can be used with Thorlabs components or within a custom OEM assembly. Four Ø0.12" (3.0 mm) through holes are spaced 60 mm apart and provide compatibility with our 60 mm cage system. These holes can pass 4-40 or M3 screws for mounting to custom structures. Additionally, there are four Ø4.2 mm (Ø0.17") through holes spaced 50 mm apart which can be used with 6-32 or M5 screws for custom mounting. The back of the mount features four Ø4.0 mm (0.16") holes 30 mm apart with locking M3 setscrews for use with our SR-Series cage rods. A 1.5 mm hex key comes with the mount for locking these screws. SR-Series cage rods can be used to attach the ELLA1 adapter to allow for post mounting or to attach ER-Series cage rods for integration into a 30 mm cage system. The images below show three mounting options. ![]() Click for Details The rotation mount can be mounted in a 60 mm cage system by sandwiching the PCB between two cage rods using the Ø0.12" (3.0 mm) holes in the corners. ![]() Click for Details The rotation mount can be adapted to a 30 mm cage system using SR025 cage rods in the Ø0.16" (4.0 mm) holes on the back of the mount. ![]() Click for Details View Imperial Product List
The rotation mount can be adapted for post mounting using SR025 cage rods and the ELLA1 post mounitng adapter.
![]() Click to Enlarge Features of the Rotation Mount The maximum allowed weight of the mounted optic is 50 g. The load must be centered on the mount in order to acheive 50 g. In all cases of mounting and loading, ensure that nothing interferes with the moving parts of the rotation mount and that the mount and its load are securely fastened to prevent jostling during movement. Jostling of the stage or the load can cause an encoder error. Supplying PowerWhen the setup includes the interface board, power may be supplied through the Micro-B USB connector and/or the 5 VDC power socket located on the board. The electronics on the interface board convert the applied DC signal to a sinusoidal signal oscillating at the required resonance frequency. The ELL14K bundle includes a 5 VDC power supply whose connector mates with the power socket on the interface board. Delivering power through this socket also allows the Micro-B USB connector to be used for a computer to control the mount remotely. The power supplied by a computer through the USB 2.0 connection is not sufficient to power the mount. If computer control is not necessary, another option for supplying power to the mount is a portable USB 5 V battery pack connected to the Micro-B USB connector on the interface board. When the implementation does not include the interface board, the connection with the power source is made using the pins on the Picoflex® connector that is included on the rotation mount board. A pinout diagram of this connector is included in the Pin Diagram tab, and information on powering and addressing the rotation mount is given in the manual and the communications protocol manual, respectively. Operation of the MotorsThe motion of the rotation mount is controlled by forcing the piezoelectric elements to vibrate at specific ultrasonic frequencies. For each motor, there is one ultrasonic resonant frequency that will push the mount forward, and another that will pull the mount backward. Operating a motor at one of its resonance frequencies causes the tip of the motor to continuously cycle in a tight clockwise elliptical path. When the motor is driven at its other resonant frequency, the tip of the motor cycles through that same path in a counterclockwise direction. Both resonant frequencies are around 100 kHz. The total displacement at the tip of motor is a function of the mechanical load it is driving and the voltage supplied to the piezo element. In the case of no loading and a 5 V maximum driving voltage at a resonant frequency, the tip of the motor expands and contracts no more than a few microns while tracing the elliptical path. Please see The Elliptec™ Motor tab for more information and an animation illustrating the operational principle of the motors. Homing the Rotation Mount![]() Click to Enlarge The Interface Board ![]() Click to Enlarge Features of the Interface Board To Home the mount, press the BW button on the interface board, click the Home button in the Elliptec software's graphical user interface (GUI) or send the appropriate ASCII message as is specified in the communications protocol manual. The default Home position is referenced to a fixed feature on the mount assembly. If desired, the user may redefine the position of Home to be offset from the default position by up to +90° (a quarter turn in the clockwise direction). Being able to customize the Home position can be useful when synchronizing the orientations of two or more mounts. When executing the Home command, the mount first finds the approximate location of Home, and then a fine-positioning procedure is used to orient the mount at Home with an accuracy of 288.0 µrad. The user can specify whether the mount rotates in a clockwise or counterclockwise direction (as defined from the perspective of looking down on the surface of the mount) during the first phase of the homing procedure, but the fine-positioning phase is always performed in the counterclockwise direction for repeatability. Positioning the Rotation MountNote that the rotation mount is not intended for continuous operation. We recommend operation with duty cycles of less than 40% during general use, while operation with duty cycles greater than 60% should be limited to a few seconds. Before the mount may be positioned, the Home position of the mount must be found. Please see the previous section for details. The movement of the mount may be controlled through computer control via the Elliptec™ software package that may be downloaded, or by sending simple signals to digital lines on the mount's board. A link to download the software and accompanying documentation can be found in the Software tab. Multiple Elliptec devices can be be controlled using the ELLB Bus Distributor or by splicing multiple connectors onto one ribbon cable. A single bus distributor can connect up to four Elliptec devices; up to 16 devices can be connected if the buses are daisy chained. This bus can be controlled one of three ways: through an interface board (included with the bundles below) to connect to a PC running the Elliptec software, by connecting to an Arduino® or Raspberry Pi® board, or by wiring the connector pins to a user-supplied control board. Note that if an interface board is used, its on-unit buttons will be disabled. Alternatively, up to 16 devices can be spliced onto a single ribbon cord. The devices can then be simultaneously controlled by the interface board or selectively controlled by the Elliptec software. See the manual for instruction on how to splice multiple devices onto a ribbon cord and the Pin Diagrams tab for pin assignments when making custom connections. The communications protocol manual describes how to use the software to individually address each connected device. A link to download the software and accompanying documentation can be found in the Software tab. The default increment to move the mount forward and backward is 45°, and a custom increment can be set using the Elliptec software or by sending the appropriate ASCII message(s) as specified in the communications protocol manual. The Elliptec software can be used to move the mount to absolute and relative positions, in addition to jogging the mount forward or backward. The software is also used to set the jog step size, read the position of the mount, and adjust the position of Home, as is described in the previous section. Readings from the magnetic sensor, which can resolve angular increments of 23.8 µrad, are used to position the mount and when executing the Home command. The travel range of the mount is not limited, but the reported orientation of the mount is always expressed as a value between 0° and 359.99°. The minimum incremental movement of the mount is 34.9 µrad, and it can be positioned with a repeatability of 873 µrad in response to signals from the magnetic sensor. The mount learns to efficiently position itself precisely using a position error compensation algorithm. After the mount moves into a new position, it detects the error between the requested and actual positions. The position of the mount is then corrected, and an error compensation value is calculated. The algorithm is then updated with the error compensation value, so that it is applied when the mount is move to its next position. Typically, an optimum error compensation value is found after between two and six movements. Resonance FrequenciesOn power-up, the factory default setting instructs each motor driving the rotation mount to search for the resonance frequencies that will deliver the best performance. During this process, the rotation mount will translate a forward and backward by a small amount. If movement on start-up is undesirable, it is possible to disable this calibration procedure by using the serial port to initialize the frequencies on power-up. A new search for optimal resonance frequencies may be performed at any time; to maintain optimal performance, it is recommended that new searches be performed after changes in loading and/or ambient temperature. Please see the manual for details. ![]() Click to Enlarge The Components of the Elliptec Motor ![]() Click to Enlarge The Elliptec Piezoelectric Resonant Motor The Elliptec™ Piezoelectric Resonant MotorThorlabs' Elliptec™ piezo resonant motor, shown at right, is lightweight, with a mass of 1.2 g, and compact: the dimensions of the resonator housing, excluding the spring, are 8 mm x 4 mm x 20 mm. Components of the MotorThe components that compose the motor are shown at far-right. The piezoelectric element is press fit into the aluminum resonator, which has been precisely designed and machined to produce the desired elliptical motion at the tip and to interface optimally with the driven module. The free ends of the spring are integrated with the resonator housing. The wires, which are soldered to the top and bottom of the piezoelectric element, deliver the voltage signal that induces the piezoelectric element to vibrate at ultrasonic frequencies. When the motor is built into a system, the open loop of the spring is bolted to a sturdy surface that is stationary with respect to the item to be driven, and the tip of the resonator is placed in contact with the item. The purpose of the spring is to maintain constant contact between the tip of the resonator and the driven item, and the direction of motion is determined by the resonance frequency at which the piezo element is driven. Elliptical Motion and Comparison with Conventional Motors
Elliptec motors quickly and precisely position stages and mounts while never seeming to move. Their microscopic movements occur at ultrasonic frequencies and are invisible to the naked eye.
The motor is operated by driving it at one of its two resonance frequencies. A voltage signal oscillating at an ultrasonic frequency is applied to the piezoelectric chip, which responds by expanding less than a micron and then contracting back to its original dimensions at the frequency of the driving signal. This rapid-cycling change in the chip's dimensions causes a vibration in the aluminum resonator housing. When the vibration is at one of the housing's resonance frequencies, a pushing motion results at the tip of the motor. When the vibration is at the other resonance frequency a pulling motion results. As illustrated in the video, the pulling and pushing motions result from the tip of the motor tracing an elliptical path in space when the motor operates at resonance. The selected resonance frequency controls the direction of the cyclical motion. The motor's tip traces one half of the ellipse as it expands and the other half as it contracts. When the motor pushes the driven item, the motor's tip is in contact with the item while the tip expands; the two are not in contact while the tip contracts. The converse is true when the motor pulls the driven item in the opposite direction. The total displacement at the tip of the motor is a function of both the mechanical load it is driving and the voltage supplied to the piezo element. The maximum displacement can be up to a few microns when the peak driving voltage is 5 V. The motor behaves in many ways like a DC or electromagnetic stepper motor, but it does not suffer from many of the drawbacks of these conventional motors. Unlike conventional electromagnetic motors, which must overcome inertial delays to come to a stop, the highly dynamic Elliptec motor can stop within microseconds. As it has no gears, it does not exhibit backlash. Since it possesses no magnets, it is compatible with use in environments sensitive to electromagnetic interference. The motion of the driven element is continuous and smooth. As the tip of the motor must be in contact with the driven item to induce motion, the motor possesses the safety feature of an inherent friction brake. When in contact with a plastic surface, the motor operates virtually silently. For OEM applications, the motor can be manufactured in volume at low cost, and it can be driven by inexpensive analog electronics. It does not require microprocessors or software; however it is compatible for use with them. ![]() Click to Enlarge The Elliptec Piezoelectric Resonant Motor Control Software GUI Software for Devices Driven by Elliptec™ Piezoelectric Resonant MotorsAll devices based on the Elliptec™ resonant piezo motor may be controlled by the Elliptec system software, which features an intuitive graphical user interface (GUI). The source code, in C# format, is included in software bundle available for download, and custom applications can be created in any language. The image at right shows a screen capture of the GUI, and the button that follows links to the download page. Commands are entered in the Sequencer command / wait order section located at the center-left of the GUI. An example of a sequence of commands that might be sent to the device is "Aho0" to move to the rotation stage at address "A" to the home position in the clockwise direction, and then "Afw" to move the stage at address "A" forward by the jog increment. The command "As1" is used to perform the frequency search that will identify the optimal resonant frequencies, for the current operating conditions, for Motor 1 at adddress "A."
Rotation Mount and Stage Selection GuideThorlabs offers a wide variety of manual and motorized rotation mounts and stages. Rotation mounts are designed with an inner bore to mount a Ø1/2", Ø1", or Ø2" optic, while rotation stages are designed with mounting taps to attach a variety of components or systems. Motorized options are powered by a DC Servo motor, 2 phase stepper motor, or an Elliptec™ resonant piezo motor. Each offers 360° of continuous rotation. Manual Rotation Mounts
Manual Rotation Stages
Motorized Rotation Mounts and Stages
![]() ![]() Click to Enlarge The motors' aluminum tips contact the black plastic track encircling the rotation mount. This track should not be touched to prevent debris and oil building up on the track. ![]() Click to Enlarge The ELL14K Rotation Bundle rotates a test polarizer between a master polarizer and a beamsplitter in a 60 mm Cage System.
The Rotation Mount Bundle is a complete package that includes the ELL14 rotation mount. The ELL14K package facilitates quick integration of the rotation mount into laboratory setups and other experimental applications. It also provides a convenient means to evaluate incorporating this technology into OEM applications. The tips of both motor housings are in firm contact with the plastic track encircling the rotation mount, as can be seen in the image at the far-right. The motors are installed with opposite orientations and clockwise (and counterclockwise) rotation occurs when one motor pushes the track forward while the other pulls it backward.
![]() ![]() Click to Enlarge Features of the Rotation mount This Rotation Mount is offered to meet the needs of applications whose designs require multiple networked Elliptec resonant motor products. It possesses an SM1-threaded mount for holding Ø1" optics. Details describing the dimensions, including the spacing of mounting holes, and other specifications of the mount are given in the Specs tab. Please contact us to discuss customizing the rotation mount. ![]()
![]() Click to Enlarge A single bus distributor can be used to control up to four Elliptec devices. The bus can be connected to a PC using the interface board provided with the bundles sold above. Note that the bus is then controlled by the Elliptec software and that the buttons on the interface board are disabled.
The ELLB Bus Distributor connects up to four Elliptec™ devices. Connected devices can be controlled with or without the interface board included with the above bundles. When using the interface board, each connected device is controlled remotely by a PC running the Elliptec software package. The interface board connects to the bus's input port labeled REMOTE; once connected, the interface board's buttons are disabled. For control without using the interface board, see the Pin Diagrams tab for custom connections. Multiple ELLB Bus Distributors can be daisy chained to control and power up to 16 Elliptec devices; simply connect one of the four MODULE outputs to the second board's REMOTE input. Indicator LEDs are provided to show which device is active. The communications protocol manual describes how to use the software to individually address each connected device. A link to download the software and accompanying documentation can be found in the Software tab. The bus includes a Ø6.3 mm power connector that supports a 5 V supply with a maximum current of 4 A. As more devices are connected, simultaneous control of the units will require more current to be provided by the power supply; please see the Specs tab for the amount of current drawn by each Ellitpec device. Power supply options provided by Thorlabs include the TPS101 5 V, 2 A power supply and the 5 V, 1 A supply included with the above bundles. Depending on the current draw of the Elliptec devices connected, these supplies provides enough current to power two devices simultaneously. Fourteen control pins, detailed in the image to the right, are included for additional functionality. Four pairs of pins are each shorted with a jumper that, when in place, enables the Elliptec software to receive feedback from connected Elliptec devices. The pair of pins labeled LED is shorted with a jumper that, when removed, will disable the indicator LEDs. The 5V and GND allow an optional, user-provided 5 V, 2 A power supply to be used in place of a source connected to the Ø6.3 mm power connector. The RX and TX pins can be used to control the bus with a Raspberry Pi® or Arduino® board, respectively, instead of the Elliptec interface board. The board is mounted using the Ø3.5 mm through holes provided in each corner. Four 8-conductor, 28 AWG ribbon cables are included.
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