shunt strips between the magnet and tube that would shield or bypass a portion of the permanent magnet's field. And most have totally dead tubes, or tubes that might be put on life support requiring additional a different HeNe laser power supply or more. But if two orthogonally polarized modes could be forced to oscillate such that they differ only by the birefringence frequency, a low frequency beat would be produced. There may be some low level additional modes contributing to these when music in the movies essay near the peaks and the center of the gain curve, but for the purposes of this discussion, they can be ignored. There is also no beat at any time during mode sweep. Only 2 lasing modes are present most of the time with 3 appearing when a mode is near the center and a maximum. There are 2 modes most of the time with a mode hop from one end of the gain curve to the other occurring when the mode amplitude decreases to about 20 percent of the maximum. The feedback had to use the output rather than the waste beam since only there are the Zeeman modes converted to linear polarized modes.
The scope clearly shows the period changing based on the mirror direction and velocity even at this low speed. Modes and Beat Frequency of HP-5501A HeNe Laser Tube 1 With Strong Transverse Magnetic Field 1 is a plot showing the effect of moving the magnets closer to produce a stronger magnetic field. so you may have to buy a few before getting one that is suitable. The alternative of shifting the lock point would also change the optical frequency. For maximum REF, the rod pulled all the way out placing the magnet in approximately the normal position with its coverage coincident with the tube's discharge. This isn't entirely surprising given the poor health of Tube. I was going to suggest Sargent, Scully and Lamb as a good (but still messy) discussion of the subject, but when I looked on my home office bookshelf I found instead an old copy.
If the tube would have fit inside magnetron ring magnets, I would have used a stack of them but this tube is a bit too wide. ;-) Converting an HP/Agilent Metrology Laser into a Basic Stabilized HeNe Laser Literally thousands of 5517 and other HP/Agilent lasers are in existence and many of these turn up surplus, usually with bad tubes but good everything else including the HeNe laser power supply and. See Photo of Two-Frequency Interferometer Laser Tester. The field for a 5517C is on average somewhat higher than for a 5517B even for a new laser, but the diagrams are not necessarily totally to scale. With the addition of a dual op-amp boost circuit, the output will be almost 60 V p-p, more than enough for several FSRs of scan range. For multi-transverse mode tubes, there would also be beats at much lower frequencies but all these HeNe barcode scanner tubes operate TEM00.) The effect of the magnetic field was confirmed by moving a magnet in the vicinity of the tube which would generate all sorts. The beat is a fairly pure sine wave much of the time but there are periods where multiple frequencies are oscillating. For the photo, the USB cable is plugged in only to provide 5 VDC power from a wall adapter and is not connected to a computer.
The value of 160 g for the electromagnetic solenoid is believed to be fairly accurate based both on its construction and actual gauss measurements using the device described in the section: Simple Gauss Meter for Measuring Zeeman Magnet Strength However, for all these magnets, the. This is the identical magnet configuration as in the plot with the multiple magnet orientations, above. Umeda,.Tsukiji, and. So, I was about to conclude that a modified tube is essential in achieving a higher REF frequency. The normal plot and one with the 120 g field look remarkably similar one was shifted over so the "Xs" where the red and blue modes intersect lined up and red and blue were interchanged. A short random polarized HeNe laser tube is surrounded by a powerful cylindrical magnet with its field oriented along the axis of the tube. The gains were equalized so the the measured total power (without the beamsplitter) and the computed total power were the same. These have a typical output power of over 1 mW thus producing around.5 mW in a single mode when dual mode stabilization is used.