Recent content by matheyrichs

  1. M

    Polarization in Interferometry

    Andy Resnick, TGarzarella, & RedBelly98, Thanks a bunch for the explanations! I appreciate it! - M
  2. M

    Polarization in Interferometry

    I'm actually only using one source at a time. But since a Mach-Zender interferometer has 2 different entry points, the two free faces of the input beam splitter, I'm using 2 lasers. This way I can take a holographic interferogram at a single wavelength, then using shutters switch wavelengths...
  3. M

    Polarization in Interferometry

    I'm using 2 non-polarizing beam-splitter cubes, a HeNe and a DPSS laser. I understand that interfering two beams of similar polarization will produce a better fringe pattern than interfering say one S- and one P-polarized wave together (should produce no interference). But it's not clear to...
  4. M

    Polarization in Interferometry

    I'm working on a laser-based holographic interferometry system. Basically, I produce a linear fringe pattern with a Mach-Zender style interferometer setup. Then when I put a transparent sample in one of the beam pathways (cell cultures), I can determine the phase offset produced based on the...
  5. M

    Common mode noise and balanced detectors

    I'm working on a laser interferometry system that uses a pair of balanced photodetectors to record the signal. Each detector is on a separate port of a beamsplitter cube, and as a result receives (in theory) the SAME signal. The rationale for using the balanced detectors is that "they reject...
  6. M

    Calculate Efficiency of 10.0 kW Motor for 8.5 kg Elevator

    are there any people in the elevator?? :-p I'm not sure. 833/10,000 is certainly only 8.33%. I also did the problem a different way, substituting the initial start and end and got the same answer. Check the problem again and make sure V_elevator and P_motor are actually 1 m/s and 10kW as...
  7. M

    Calculate Efficiency of 10.0 kW Motor for 8.5 kg Elevator

    petuniac, you should not be using 10kW and the elevator's speed in the same equation. It sounds like 10kW is your Power in, the power supplied to the motor. efficiency is also Pout/Pin. So Pout is the amount of power used while lifting the elevator. For this calculation you can in...
  8. M

    Calculate Efficiency of 10.0 kW Motor for 8.5 kg Elevator

    if you want to approach this using time and simply potential energy change, you can set an initial condition and a final condition: ex) initial condition: height=0m t=0 final condition: height=10m t=10s Then play with (delta)E in a much simpler way.
  9. M

    MATLAB Matlab Image Acquisition Problem

    I've found the answer to my question. In case anyone else has similar issues: You've got to get to the Device Specific Parameters. This is accessed by 1) creating a videoinput object; 2) creating a source object attached to the video input; and 3) asking nicely :p. See below...
  10. M

    MATLAB MATLAB - changing variable name with each iteration?

    rteng, when iterating through the loop, you can store each vector as a separate row within a matrix. for example: for i=1:100; AcquiredData= %however you acquire here-ish%; AllData(i,:)=AcquiredData; end basically use AcquiredData as a variable that changes each loop, and...
  11. M

    MATLAB Matlab Image Acquisition Problem

    I'm working on a laser microscopy setup and am having issues with Matlab image acquisition. I'm using an AVT Pike-032B CCD camera that is a 1394 camera. Most importantly, I'm interfacing to it using the CMU 'dcam' library, which provides pretty nice control through a program "1394 Camera...
  12. M

    Laser current modulation issues

    To wrap up this issue, this is my implemented successful solution: I had a power MOSFET sitting around the lab, and did a bit of research on it (IRFZ44N). It has a lot more capability than I need: +-20V gate voltage +-50V drain-source voltage max 49A max drain-to-source current...
  13. M

    Laser current modulation issues

    Since I already have a USB I/O device for the 0-5V analog control (measurementcomputing*dot*com USB-1208LS) capable of sourcing 30mA, I figure that a solid-state relay should work. Berkeman, the one you've recommended is unfortunately not an in-stock item and I'm betting I'd need to order...
  14. M

    Laser current modulation issues

    I guess I could use one... but: I thought that reed relays are for low-current, slow switching applications and aren't particularly durable due to the moving contacts. I need to be able to switch my laser on and off at ~20-40Hz, and I figure that a transistor would be better for that...
  15. M

    Laser current modulation issues

    Yarr. I made a HUGE initial assumption that now changes my problem completely. The "modulation control" output has 3 wires: red, black, and yellow. After probing voltages while playing with the input, I've determined that the red and black are standard dc power, whatever is input before the...
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