> A laser interferometer is on my todo list. I've acquired all of the > optics on ebay for a total of a few hundred dollars. I've built a power > supply. The major part I'm missing is the counting and interpolating > electronics with a computer interface.
Hi Ken, the heterodyne interferometers I have found described mostly use a two-frequency laser which emits two orthogonal polarizations with slightly (500kHz? or in your case 4 MHz) different frequency. Did you find a Zeeman-stabilized two-frequency laser on ebay? Or are you planning to DIY and put magnets around a normal HeNe tube? Sams Laser FAQ has a description: http://www.repairfaq.org/sam/laserchn.htm#chndzees The other method is to use an acousto-optic modulator to shift the frequency of the light. But the papers I've found use two modulators, and I only have one to spare right now... If I can either find a two-frequency HeNe or DIY with magnets then I'd be interested in testing this, possibly with the m5i20 (already has fpga code for fast encoder counters) for data acquisition. Anders ------------------------------------------------------------------------------ This SF.Net email is sponsored by the Verizon Developer Community Take advantage of Verizon's best-in-class app development support A streamlined, 14 day to market process makes app distribution fast and easy Join now and get one step closer to millions of Verizon customers http://p.sf.net/sfu/verizon-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
