Instructions for this lab are still delivered on paper or PDF file, available in the labs.
A few things have been added, however, and the experiments will soon be converted to use fiber-optic FC connectors and some fiber-optic cables. This is being done to simplify measurements you now can do using beam-profilers in the lab, which have FC connectors as a precise way to attach fiber-optics.
Near-field profiler: the end of the fiber is imaged, with 30x magnification, onto a CCD camera; this shows the intensity pattern of light at the end of the fiber
Far-field profiler: the beam simply propagates many fiber-diameters away from the fiber, and the expanded beam is recorded at a CCD camera. This optical field is essentially the Fourier transform of the near-field one, and includes diffraction, and the intensity is the magnitude of this Fourier transform.
He-Ne beam profiler: This couples a 0.1x demagnifying telescope, and fits the whole HeNe beam intensity pattern onto a CCD to be recorded. This lets you do analysis of the tranverse modes of the HeNe, and even quantitatively compare them to the theory of Hermite-Gaussian and Laguerre modes.
The software for collection and analyis for these is:
Logitech Quick Cam: proprietary software for the company's webcams, available as a download if you want to convert the format of images saved in the lab. If the previous link is out of date, go to the Logitech website, and look for downloads for the QuickCam Express webcam.
NIH Image (or Scion's adaptation to PCs, Scion Image): NIH Image is freeware for the Macintosh, developed by the National Institutes of Health (USA), downloadable here; Scion Image is the free port of this software to PCs under Windows, and after noting that you don't own a Scion framegrabber card, it permits you to open and to analyze images. The software is also available online as a Javascript applet. Once you've collected your data, these will let you analyze things on your own machine away from the lab, or to clean things up for your formal report.
We're currently looking into doing both acquisition and some analysis using LabVIEW alone.
CD-R/RW burner: Image files take up space; a USB-2-wired CD-R/RW burner is available for you to preserve your work, to keep a copy for putting results into a formal report, or to take results home for further analysis. You may have to put your student card on deposit in the Equipment Room in exhange for the burner, or it may be available on the beam-profiling computer. Note that only certain ports on the computers may be USB-2, needed for high data throughputs.
Last revised: 7 April 2003 -- rsm