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What is meant by thread pitch?
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Thread pitch is the distance between adjacent threads measured parallel to the thread axis. From the standpoint of threaded drive mechanism like a micrometer or a thumbscrew, thread pitch defines travel for exactly one rotation of the knob. For example, since the 07 MAT 703 Fine-Touch thumbscrew has a thread pitch of 125um, its spindle will travel 125um per each rotation of the knob. Thread pitch for inch parts is specified in terms of threads per inch (TPI).
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I mounted one of your 07 TLC 204 linear translation stages on a 07 TSR 204 "L" bracket for vertical travel but noticed that the top of the stage drops down when loaded and is no longer in contact with the micrometer. How can I fix this?
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If this is happening then you have mounted the translation stage with its micrometer pointed upwards and there are two ways to fix this problem: 1) Mount the translation stage so the micrometer is pointed down or, 2) remove the stage from the "L" bracket, mount any one of the 07 BMA-series mounting plates to the bottom of the stage and remount the stage on to the "L" bracket so that the top of the stage is in contact with the "L" bracket.
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How do I make an in-line refractive beam steerer using your 02 PRW-series wedge prisms?
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Rotating two wedge prisms of equal power about an axis parallel to their adjacent faces, a beam can be steered in any direction within 4X the wedge deviation angle. Wedge prisms can be held using the 07 HPW 001 wedge prism adaptor and can be rotated using the 07 HPR 221, 07 HPT 231 or the 07 HPT 731 polarizer rotators.
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When is it better to use a flexure mirror mount over a standard kinematic mount?
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The one main advantage the flexure mount has over the kinematic mount is its ability to support heavier loads. The flexures provide significantly more vertical support than the springs in kinematic mounts.
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I want to be able to mount one of your 07 MAT 703 Fine Touch thumbscrew drives on to one of your 07 TLC 224 translation stages. Will it fit?
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Yes. In general, all drives (thumbscrew, micrometer, differential and motorized) with equivalent travel ranges have the same mounting interface. In this specific case, the 07 TLC 224 has a travel range of 13 mm as does the 07 MAT 703 so it will fit properly.
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I noticed that resolution specification for your manual actuators differ between the micrometer and thumbscrew drives in that the specification for the micrometer is postulated with the term "incremental mark". Is this really the best resolution the drive is capable of?
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No, the drive can reach better resolutions. The micrometer has graduated markings or "incremental marks" whereas the thumbscrew drive does not. Since resolution is generally understood to be the smallest movement an actuator can make, it can be highly dependent on the person who makes the adjustment. For comparative purposes, resolution on drives with "incremental marks" is referenced in terms if the smallest incremental mark which on most micrometers is 10um. The actual smallest movement the micrometer can make is one half to a third of the smallest incremental mark.
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When should I use a round-tipped actuator vs. a flat-tipped actuator?
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It depends on how accurately you are able mount to your actuator. When mounting an actuator, the goal is to minimize contact-point friction. Contact-point friction is the result of a misalignment between the actuator tip and the contact point and obviously, a round tip interfaces to a flat contact point and vise versa. Contact-point friction for a flat-tipped actuator increases as the center of rotation of the actuator's spindle is offset from the center of the round contact point. For a round-tipped actuator, contact-point friction increased the more the axis of rotation of the actuator's spindle is angularly misaligned to the flat contact point.
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When should I use ball bearing vs. crossed-roller bearing translation stages?
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Both types have advantages and disadvantages. Crossed-roller bearings can handle higher load capacities and are more resistant to permanent damage from drops but they tend to be more expensive and are more sensitive to bearing-way contamination such as dirt particulates. Ball bearings are less expensive and more resistant to bearing-way contamination owing to point contact with the bearing way.
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I purchased two of your 07 TXC 724 translation stages to make an xy translation stage but can't find the OrthoPins.
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The 2 OrthoPins are located in two separate compartments on the side of the stage opposite the micrometer. Setscrews must be removed to gain access to the OrthoPins.
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Can I motorize one of your 07 MHT 225 or 07 MHT 227 kinematic mirror mounts?
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Yes. You can motorize one of our 07 MHT 225 or 07 MHT 227 kinematic mirror mounts using two of either the 07 EAS 503 or 07 EAH 503 stepper-motor drives, and the 17 BSC 002 stepper-motor controller. Simply remove the thumbscrew drives from the mirror mount and replace them with the aforementioned stepper-motor drives. A third stepper-motor drives can be added as well if needed.
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Can your 40 X 40-mm center-drive translation stages be motorized?
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Yes. The 07 EAS 503/F or 07 EAH 503/F stepper-motor drives can be used to provide 13 mm of automated travel for a 40 X 40-mm center-drive translation stages. For mounting to an optical tabletop, either the 07 RPC 016 or 07 RPC 516 adaptor plate is needed depending on whether the stages is inch or metric.
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I see that you have 65X65-mm translation stages with 1 inch (25 mm) of travel ie. The 07 SSS 224/A. Can these be motorized?
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Yes, by using either the 07 EAS 504/F or 07 EAH 504/F stepper-motor drive, and the 17 BSC 002 stepper-motor controller, any of the 65X65-mm translation stages with 1 inch (25 mm) of travel can be motorized. For mounting to an optical tabletop, the 07 ORA 509, 07 RPC 013 or 07 RPC 513 adaptor plates is needed.
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I have one of your 07 TLC 224 65X65-mm, 13mm travel translation stages and one of your 07 MAM 704 micrometers with 25 mm of travel. Can I mount this to the stage to give it 25 mm of travel?
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Unfortunately this will not work. The micrometer in a 07 TLC 224 65X65-mm, 13mm travel translation stage or any 13-mm-travel translation stage has a 9.5-mm mounting diameter and the 25-mm travel micrometer has a 10-mm mounting diameter and will not fit. A 07 TLC 224/A, however, is available with 25 mm of travel.
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Do you have any side-drive motorized translation stages?
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There are no kitted systems available but one can be made from any of the 25-mm travel, 65X65 translation stages having a side-mounted micrometer and a 07 EAS 504/F stepper-motor drive.
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What is a "Flexure" Positioner?
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A flexure is a, strictionless device that relies upon the elastic deformation (flexing) of a solid material. Sliding and rolling are entirely eliminated from the design. The flexure device is limited to applications where the required travel is typically no more than 10-15% of the major dimension of the device.
In addition to having no internal friction, flexure devices have high stiffness, high load capacity, and high resistance to shock. They also exhibit a low sensitivity to vibration.
Users should be aware that in all standard flexures, there is a second-order cross coupling between axis. This movement is called arcuate motion (travel is in an arc motion). For fine positioning applications as in fiber optic alignment, and integrated optics, this is seldom a problem. In addition, if precise rectilinear movement is required, then compound flexure devices eliminate the arcuate motion and are readily available.
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Why would I want to use a Flexure Based Positioner?
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There are three "traditional" technologies used in motion positioners — dovetails, ball bearings, and roller bearings. Each of these technologies have their respective strengths (e.g.: high load capability, long travel), however, they all have varying degrees of friction and stiction. This fundamental property causes wobble, hysteresis, and/or backlash, and an uncertainty in reproducibility — limiting their practical usefulness to precision of 0.1 mm at best.
Conversely, because of the, strictionless nature of a flexure based positioner, precision on the order of 1 nm are readily achievable. Also, because of the stiffness of a flexure design, maintaining a specific position is greatly enhanced.
This sort of high precision and stiffness are mandatory in applications requiring (100 nm accuracy such as single mode fiber optic alignments integrated optics and pig tailing.)
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What are Piezoelectric Actuators?
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Piezoelectricity or pressure-electricity is a property of some crystalline materials. When these materials are compressed, they produce a voltage proportional to the applied pressure. Conversely, when an electric field is applied across the material, there is a change in its shape. Piezo-ceramics can respond rapidly to changing input voltages (microsecond time constants) and their positional resolution is limited only by the noise of the power supply.
Traditionally, high voltages (1 to 2 kV) were required to produce the desired extensions from the piezo material. This limited their acceptance because of the high cost of power supplies, noise, and reliability. Melles Griot has developed a piezo electric material that operates in the 0 to 75 V range; eliminating the traditional problems associated with piezo actuators. These new state-of-the-art devices can be coupled to our line of flexure stages yielding a positioning device capable of 5 nm precision.
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What is the difference between piezoelectric actuators with and without position feedback?
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Piezoactuators are not ideal voltage-to-displacement transducers — they exhibit nonlinear properties of hysteresis and drift. Although these properties can be overcome by approaching the final destination from one direction (unidirectional approach), a more powerful technique to eliminate them is to use a "feedback control" loop. Melles Griot has developed a range of piezoactuators with a closed loop position feedback sensor. The linearity response of these closed loop devices are better than ±0.5%, a d the noise equivalent motion is 5 nm.
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How can the autoalignment piezoactuator controller help me?
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The autoalignment piezoactuator controller, Melles Griot's automatic alignment controller, is used with our piezoelectrically controlled positioners to simplify and speed up the time-consuming alignment procedures normally experienced when testing or fabricating single-mode fiber optical components. It makes alignment automatic, signal acquisition takes a fraction of a second, alignment is maintained indefinitely, and it compensates (in real time) for movements caused by environmental disturbances.
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How does the autoalignment piezoactuator controller align a fiber to a device?
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The elegant analog system used by the autoalignment piezoactuator controller employs a principle previously used by radar engineers to track their targets. By rotating the cone of light emitted from a source fiber, the light entering the target device is modulated at the frequency of rotation. This modulation is recovered by the autoalignment piezoactuator controller's detectors and compared to the phase of the signal used to rotate the source fiber. This information is decoded into vertical and horizontal components of displacement and used to close the loop on the source fiber. Consequently, this process brings the fiber and device into precise alignment. Displacement errors are decoded in a few cycles of modulation, typically several milliseconds; consequently, alignment is achieved in less than a second.
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What is the main advantage of the autoalignment piezoactuator controller?
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Unlike other alignment techniques, which use either programmed scanning algorithms or video processing techniques, the autoalignment piezoactuator controller's operation does not require a computer. It operates independently, ensuring at all times, that the critical axes are maintained in precise alignment. This occurs while other concurrent operations are carried out, usually under the control of a computer.
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What specific functions does the autoalignment piezoactuator controller provide?
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The autoalignment piezoactuator controller solves the major problems of:
1. Acquiring an initial throughput signal and then maximizing it through constant active adjustment of the appropriate axes of a piezo positioner — normally the vertical (Z) and horizontal axes (Y).
2. Compensating, in real time, for micrometer scale misalignment in Z and Y, caused by interaction between axes, as axial displacement (X), pitch (y), yaw (z), and roll (x) are adjusted for optimum throughput power.
3. Correcting environmental disturbances caused by temperature changes or vibrations.
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How do I align a fiber to a device optimizing five or six axes?
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In its more usual configuration, the autoalignment piezoactuator controller provides continuous and automatic optimization of coupled power, between, for example, a fiber and an I/O device - by servo controlling the vertical and horizontal axes of a positioner fitted with piezoelectric actuators. When a throughput signal is first acquired, the autoalignment piezoactuator controller immediately optimizes this signal by adjusting the vertical and horizontal position of the fiber. This takes a fraction of a second. Tracking is then initiated and the user is able, with the use of an additional positioner, such as a flexure roll stage to optimize the angular axes.
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What about interaction between axes?
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A pitch (y) adjustment will interact principally with the Z axis, causing vertical misalignment, yaw (θz) will tend to misalign Y, while roll (x) will interact with both Y and Z. However, the autoalignment piezoactuator controller actively compensates for any interaction between axes by constantly and automatically maximizing the vertical (Z), and horizontal (Y) axes.
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How useful is the CRT display?
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A CRT display provides real-time visual control of the alignment process. It displays the autoalignment piezoactuator controller's operating parameters, indicating the extent and direction of the piezo electric movements, both vertically and horizontally — i.e., the position of the circle, and the modulation depth — i.e., the diameter of the circle. The upper right hand corner of the screen represents the maximum piezo extension position. By maintaining the scanning circle on the screen, the user ensures that piezo travel limits are not exceeded — and that loss of throughput signal never occurs.
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I wish to automatically align a fiber into and out of an integrated optical device.
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It is practical to use more than one autoalignment piezoactuator controller in a single optical path simultaneously. To achieve this, a user must specify two controllers set to different scanning (modulation) frequencies. The autoalignment piezoactuator controller utilizes highly selective phase sensitive detectors, which detect only their own frequency. This allows multiple alignments to be achieved in a single optical path from a single detector.
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I want to permanently attach fibers. Can the autoalignment piezoactuator controller follow relative movements during a bonding process?
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Yes, the autoalignment piezoactuator controller has the ability to accommodate movements between a device and fiber during a pig tailing operation. However, when attaching fibers, two options are available, depending on the response of the throughput signal to the bonding process itself.
1. Remain in TRACK mode — The autoalignment piezoactuator controller follows any relative movements by constantly and automatically optimizing throughput power.
2. Switch to LATCH mode — this freezes the vertical and horizontal positions at optimum coupling.
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Do I need to provide a computer?
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Yes, the autoalignment piezoactuator controller is hardware rather than a software product. It is not based on a software algorithm but uses an instantaneous analog technique to accomplish alignment.
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When should I consider using a piezoelectric controller having feedback?
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When you need to read absolute position at the nanometric level. For example in applications such as:
(a) Near-field measurements — where position and power levels must be mapped.
(b) When precise position adjustments are required - to compensate for misalignment during welding or soldering processes.
(c) Ultra critical control of the fiber standoff distance.
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