Abstract
An interference of two beams coming from one laser is a well-known and popular experiment. But is it possible to obtain interference fringes using two completely independent laser sources? If the answer is ‘yes’, is such an observation available in a typical optical laboratory? We show a simple but spectacular method of observing such an interference, using very common continuous wave He–Ne lasers as well as diode lasers often found in atomic physics laboratories. The contrast of the fringes ranges from 27% to 87%, depending on the laser properties. The method works for both single and multi-mode unstabilized He–Ne lasers. The fringes are visible on a scientific as well as on a common security camera.
Highlights
There is a popular notion saying that the only ‘true’ or ‘legitimate’ interference takes place when interfering beams are derived from one laser source, as in a Michelson or Mach–Zehnder interferometer
The generic configuration used to observe interference fringes is shown in figure 1(a), where both beams usually originate from the same laser source
We used this setup for He–Ne lasers only; Beams, first mixed on a glass plate, were passing through common acousto-optic modulators (AOM), used to turn on/off 1st diffraction order directed towards a CCD camera
Summary
There is a popular notion saying that the only ‘true’ or ‘legitimate’ interference takes place when interfering beams are derived from one laser source, as in a Michelson or Mach–Zehnder interferometer. The first and the best known one is the experiment reported by Magyar and Mandel, performed using two ruby lasers in the optical region [1] Another one, somehow forgotten in our opinion, is the demonstration shown by Radloff for two single-mode helium–neon (He–Ne) lasers, enclosed in the same quartz block to improve their stability [2]. He–Ne lasers are very common as both scientific and demonstration apparatus, whereas the diode lasers are a workhorse in atomic physics laboratories. These two types of lasers have different longitudinal mode structure and it was very interesting to find a way to demonstrate the interference fringes for both of them.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
