Measurement Readout for Encoders & Homodyne & Heterodyne Interferometers-SG-μMD2

Description: µMD2 consists of a kit of parts to construct a low cost readout for heterodyne interferometers using two frequency lasers and homodyne interferometers using single frequency lasers (as well as linear or rotary encoders, ring laser gyros, robot arm joints, construction cranes ;-), and similar applications providing RS422 compatible or TTL Quad-A-B signals). For Quad-Sin-Cos signals, conversion from analog to digital circuitry may be required (not included). µMD2 is based on a Teensy 4.0 Arduino-compatible micro-controller and provides functions similar to that of an HP-5508A measurement display and more. The firmware requires a PC with USB port running Windows XP or later and .net 4.0 or later for the custom µMD Graphical User Interface (GUI, but may require Win 7 or later to change the firmware). (The GUI is the same one used for µMD0 and µMD1) The PC is NOT included but most systems (desktops, laptops, or netbooks) more recent than the Jurassic period should be satisfactory. :) So dust off that old computer and put it to good use! Sorry, µMD2 does not run on a phone - yet! But there is an optional tiny OLED display that mounts on the SG-µMD2 PCB that will at least show activity on up to three axes (though formatting may be rough, not much more than counts, see second photo, though there is nothing to prevent you from enhancing it). The Graphical User Interface (GUI) provides real-time displacement and velocity measurements on up to three independent axes, as well as optional frequency analysis of the displacement data (FFT). See the photos for examples of the typical display. Readout may be set for linear or rotary. Other features include logging so that data can be exported to a data analysis application like Matlab or Excel; and Test Mode which has it's own function generator for simulated data which can be displayed and processed just like real data for verifying behavior or just checking out operation. And for custom applications, the GUI can be bypassed entirely with data from the SG-µMD2 board input directly to your software. The serial data link works on most versions of Linux as well, the driver is built in. This is very powerful by itself because of the piping functionality under Linux. The GUI may actually work as-is on Wine under Linux also but I have no way to confirm. There is much more information in the official "µMD2 Installation and Operation Manual". Google will find it. With typical single-frequency HeNe laser for homodyne it is ~40 nm for displacement. For encoders and the like, it is 4 counts per Quad-A-B cycle. For heterodyne, the input frequency limit should be well above 50 MHz thus supporting Zygo 77XX laser-based interferometers running with a split frequency of 20 MHz. With a Plane Mirror Interferometer, the native resolution using µMD2 with a two frequency laser for heterodyne is ~80 nm for displacement. Interpolation is not currently available but it is anticipated there will be a version soon (or at least someday) which will be better than the one in µMD1. Interpolation will be a free firmware upgrade, though a few jumpers may be required on the PCB. With interpolation, the resolution will be improved by at least a factor of 10 (and probably much more) resulting in an absolute resolution below 20 nm with easily detectable changes below 1 nm. For referance, 1 nm is the space taken up by 8 hydrogen atoms sitting peacefully side-by-side. ;-) But the GUI has an adjustable moving average, so even without firmware interpolation, for slowly changing displacement, the usable resolution is much better than the native resolution. With homodyne for all practical purposes, there is no upper limit to the Quad-A-B input frequency. Decoding is done via hardware inside the Teensy and should function at many 10s of MHz. There is no interpolation with homodyne and none is planned, but if 40 nm resolution isn't good enough for you, in-line interpolation widgets are available as well as chips to roll your own. There are no plans to offer an assembled version of the SG-µMD2 on a continuing basis though there may be one from time-to-time. But as can be seen from the photos, there are only a few easy to install parts and Heathkit™-style step-by-step assembly instructions will be provided. For a minimal system (single axis without signal LEDs or OLED display), it's around a dozen parts through-hole in addition to the Teensy socket (third photo). Really. ;-) And even if you have never done fine soldering, there must be someone you know who has. A version of the µMD2 firmware will be pre-loaded on the Teensy 4.0 which will probably be single axis heterodyne without the OLED. The firmware version currently differs for homodyne and heterodyne. It also must be set up for the correct number of axes and to enable the optional OLED, which are parameters at the start of the code. So it will likely be necessary to install the correct version set with those parameters. However, since it uses the Arduino IDE with the Teensyduino extension, this is straightforward and well documented on-line and in the manual. The hardware options really differ only in terms of the number of line receivers with their associated parts and whether the OLED is installed. Here is what's included:SG-µMD2 V1.22 PCB or V1.23 PCB.USB A male to USB B Micro male cable. The length could be as short as 10 cm so it may be worth having a USB A M-F extension cable (not included).UA9637 or UA9639 RS422 dual line receiver IC(s). Screw terminal blocks for the inputs. If you would prefer Molex-style headers (with mating pins and shells) in place of the screw terminal blocks shown in the photos to easily disconnect the PCB from your system, connectors are available. Please contact me before buying if interested. The cost is the same pending available stock.All other electronic components required to populate the SG-µMD2 PCB including sockets for the ICs and Teensy.OLED display and associated parts if selected as Yes.Link to the µMD2 Installation and operation manual. The manual includes full specifications, wiring instructions, Windows GUI operation, and links to the detailed assembly instructions, latest firmware and GUI software. If you want to see it now, search for "Micro Measurement Display 2".Number of axes:1-Axis Homodyne µMD2 Kit or 1-Axis Heterodyne µMD2 Kit: One line receiver chip. The hardware is identical. 2-Axis Homodyne µMD2 Kit or 3-Axis Heterodyne µMD2 Kit (which also supports 2 heterodyne axes): Two line receiver chips.3-Axis Homodyne µMD2 Kit (which also supports 3 heterodyne axes): Three line receiver chips. The Axis Upgrade option enables a previous purchased µMD2 to have one homodyne axis or two heterodyne axes added. (Maximum of 3 axes of either regardless and not at the same time!)Also available:Bare SG-µMD2 PCB ONLY.Bare SG-µMD2 PCB and Teensy 4.0 ONLY. The OLED is an option.There is a link to a Digikey CART for the electronic parts in the assembly manual. IMPORTANT: The laser, interferometer optics, optical encoders, or construction crane :-) are NOT included!!!! µMD2 will work with all common single frequency lasers like the Melles Griot/Pacific Lasertec 05-STP-91x and two frequency lasers like the HP/Agilent/Keysight 5517, and other commercial as well as home-built lasers such as those constructed using parts in my listing for stabilized HeNe Laser Kits. Interferometer optics are readily available on eBay, or can be constructed from basic optical components - polarizing beam-splitters, waveplates, and retro-reflectors.. For homodyne, a suitable detector can be built using inexpensive parts. While there are locations to add a reference level voltage divider to the PCB, voltage comparators to convert from analog signals to RS422 may be required unless all signal amplitudes and offsets are the same and there is adequate drive capability. For heterodyne, a simple optical receiver can be built where where there is adequate power, but using a commercial one like the HP10780 is generally a better solution. Kits for both types are available - The SGAB2 Quad-A-B preamp and SGOR3 optical receiver. The last photo shows a custom setup using a Melles Griot 05-STP-910 single frequency laser modified to be two-frequency, along with an HP 10706A Plane Mirror Interferometer, HP 10780 optical receivers for the REF and MEAS signals, and a loudspeaker with planar mirror on a translation stage for testing µMD2. Lifetime (yours or however long you remain interested in this stuff, or mine) tech support will be provided via email. ;) Note that it is possible to purchase the required parts from an electronics distributor (except the SG-µMD2 PCB) at a fraction of what I'm charging here and you could build the thing on a piece of prototyping board. I'll still provide tech support, though it might not be quite as friendly. ;) It was not my intent to offer the complete kits in quantity to a single buyer. So going with just the PCBs and Digikey Cart is highly recommended. And even for 2 units, the savings is significant. Lasers, interferometer optics, detectors, cables, and cable parts, as well as "Hobbyist Special" kits with lasers and optics may be available. Contact me with specific requirements and/or check out my other listings. Systems for heterodyne interferometry using two frequency lasers are available in my other listings. Also available are BLANK PCBs for SG-OR3, SG-QAB2, or both. But these are only needed if you are rolling your own electronics. A Web search will find info on these. OR3 is similar to an HP 10780 and is used with a two frequency laser to convert the optical heterodyne signal to RS422. QAB2 converts detected baseband optical signals to RS422. Sorry, I don't have kits for either of these but the manuals have complete parts lists and step-by-step assembly instructions. IMPORTANT: This is NOT a turnkey system - some assembly is required. Basic electronics skills like fine soldering and basic testing using a DMM, as well as additional parts including wire or cable, are required. And you can't use your 100 watt Weller soldering gun or propane torch for this, it requires a fine tip preferably temperature-controlled iron. A desoldering tool is also desirable should you make a mistake (GASP!). There is no warranty if you screw up assembly due to poor soldering technique. If you have no experience with fine soldering, find someone who does. :-) The handling time is listed as 5 days because sometimes people want other items included with SG-µMD2, which I may need to order. eBay seems to be anal about this even if buyers never complain. But shipping is typically same day for just SG-µMD2. Returns accepted ONLY if everything is in original condition and the warranty sticker on the Teensy package is intact. This also means that there are no 10 pound globs of solder stuck to the PCB! :-( :) And there may be a retesting fee. For international sales, please contact me if no option is listed for your country. Thanks for looking! :-) --- sam

Price: 10 USD

Location: Bala Cynwyd, Pennsylvania

End Time: 2024-08-24T00:00:28.000Z

Shipping Cost: N/A USD