Ay 105: Optical Astronomy Instrumentation Lab
(Spring Term 2012)

Class Logistics

Instructors: Lynne Hillenbrand (lah@astro; x6587) and Chris Martin (cmartin@srl ; x4243)
Grade-A-1 Teaching Assistant: Michael Bottom (mbottom@astro )

Meetings: Mondays 4-7 pm and Wednesdays 3-6 pm

The laboratory sessions are twice each week, roughly 3 hours per class meeting. Each week will begin with a short lecture in 219 Cahill followed by laboratory work in 29 Cahill -- basement level, southwest corner, phone number x8481. There are two optical benches in the teaching lab. Depending on enrollment, you will work in groups of 2-4.

After the lab work is completed analysis and interpretation will be required. There is a student account for this course on the Ay computing cluster with software including various programming language compilers, plotting packages, IDL, IRAF, etc. Many students work outside of this infrastructure, but please ask for access to the account if you need it.

Background

This course is recommended for juniors and seniors (sophomores also welcome, but not necessarily recommended) who wish to gain hands-on experience with basic elements of optical astronomical instrumentation. There are 8 experiments to conduct through the term. No texts are required for this course but the studious among you likely would find the following books useful references:

-- Schroeder, D.J. (2000), Astronomical Optics
-- Rieke, G. (2003), Detection of Light
-- Howell, S.B. (2000), Handbook of CCD Astronomy
-- Glass, I.S. (1999), Handbook of Infrared Astronomy -- access via Caltech Connect

These materials are also on the Caltech course reserves list for this term.

In addition to the science you will learn, working with your peers in the lab will help develop the ``life skills" of: teamwork, critical thinking, creative problem solving, and communication.

Advice

While performing the experiments, some key concepts to keep in mind are: the importance of careful optical alignment, the manifestation of physical principles in the reality of lab setting, and the need to log measurements and estimated sources of error as well as the amplitudes in those errors. In addition to understanding how to set up and do the experiments, an important part of any laboratory class is the analysis, interpretation, and discussion of the lab in a written lab report. Each person must keep her/his own lab notebook. For each experiment you may have notes from the lab work, but then you must also produce a more formal description of the experiment, beginning-to-end.

In preparing the latter, you should imagine that you are explaining your work to a reader who has not done the experiment, rather than merely accounting for your presence in the laboratory. Please do not simply present tables of measurements, unlabeled plots, and no discussion or conclusions. The lab reports are expected to consist of the following sections:

  • I. Introduction. State the purpose of the experiment and explain, briefly, how will it be addressed with the equipment (typically half a page or more)
  • II. Equipment. Describe what equipment was set up, and why. Don't just transcribe the lab handout, but accurately describe the equipment used. Do sketch the layout. You should have enough detail to allow others to repeat your experiment (or for you to figure out what went wrong if something goes awry!)
  • III. Measurements. Describe what measurements were made, including uncertainty estimates whenever possible. Check your measured values against expectations. Make sure your error estimates are reasonable. As in all real experiments, things often do not go according to plan. Equipment may not perform properly or unforeseen snags may arise. Describe any such problems and discuss what steps were taken as a result.
  • IV. Data Analysis. Discuss how you converted your raw measurements into meaningful results, showing relevant equations and calculations. Show tables and plots when appropriate, paying attention to axis labels and explanatory captions. Answer any embedded questions in the lab description and instructions. Discuss sources of error, and quantify measurement errors in your end results, paying attention to significant digits. Clearly state your conclusions.
  • V. Interpretation and Discussion. What do your results mean? Discuss any unexpected results and try to explain them. What might you do differently the next time, and how could the lab be improved? Also, include a brief discussion of what you learned.
  • VI. Summary and Conclusion. This should refer back to the introductory material and summarize your results relative to your expectations.

    The first section could be recorded in your lab book before coming to class or you may leave room for its addition later. The next equipment, measurement, and some of the analsyis sections should be recorded during the lab session. Try to get in the habit of recording everything you do in your book as it is done. If you find that these recordings suffer in legibility or organization, you can summarize the important measurements on the following pages later. As you will be doing the experiments in groups, the in-class effort will be divided in that you will collectively figure out how to set up the equipment but one person may be recording data while another is making adjustments or reading values, etc. Thus it is acceptable to photocopy the measurements section from another partner's lab book and paste it in to your own; try to ensure that your book has all of the necessary data. Please distribute the work equally between partners--it doesn't make sense for one person to be shouldering most of the work. The write-up at home should concentrate on the analysis and interpretation / discussion sections. You are welcome to share ideas during the lab and during the analysis, but the writeup should be your own, and at the end of the lab, each person should do her/his own interpretation and summary (sections V and VI). Some hints are:

  • Be complete, including a motivating introduction and a summary conclusion.
  • Be clear, explaining the logic of your experiment from beginning to end, including what worked and what did not.
  • Be organized, using neatly produced and well-labeled plots, tables, and references. Draw figures of the experimental set-up. Define terms and variables.

    Note that the class is 10 units, with 6 units in the lab. Thus you should not spend more than 3-4 hours on the analysis and writeup. Unpolished, but CLEAR work is perfectly acceptable.

    Policies

    In order to pass this class you must do the following:

  • attend each week's warm up lecture
  • conduct the experiment in teams of your peers during the allocated hours
  • turn in a coherent lab write up each week
  • turn in a final lab notebook

    Attendance is mandatory! Approximately 35% of your grade will be based on your in-class performance and 65% on the written work your turn in.

    Your experiment should be written up in a standard laboratory notebook. Each student should write up the work independently though you will find yourselves sharing note taking duties while the experiments are conducted.

    The completed lab write-ups for a given week should be due on a date that allows them to be graded and returned in time for the follow week's lab. We need to discuss this, but I propose the lab writeups are due on the following Monday, so that they can be graded between the two lab sessions. Late lab notebooks may earn up to 80% credit only.

    Final copy of the term's work will be due on the last day of classes.

    Resources

  • Starting from the beginning, Optics 1 (from Edmund Optics)
  • Applets illustrating basic concepts of relevance to this class (from Molecular Expressions)
  • Fundamental optics from the Melles Griot company (supplier of much of our equipment)
  • Intermediate telescope optics

  • Lasers also from the Melles Griot company (pages 1-17 are the most relevant for our HeNe lasers)

  • CCD detector overview
  • Infrared astronomy and detector overview


    Schedule


    Week of Spring Term Week Beginning on Calendar Date Laboratory Activity Instructions Pictures Notes and Reading
    Week 1 2 April Introductory Meeting and Lab Tour -- -- The first class meeting will last only about 45 mintues .
    Week 2 9 April Experiment 1:
    Radiometry / Photometry     		lab pics Melles Griot note on power measurement and photodiodes
    Week 3 16 April Experiment 2:
    Geometrical Optics     		lab pics note on test pattern and, if you use the laser, Melles Griot note on shear plates (also a follow-up from Expt 1)
    Week 4 30 April Experiment 3:
    Polarizing Optics    		 lab pics coming soon michael has written a new lab for us in 2012!
    textbook info on polarized light from the venerable Jackson
    Week 5 7 May Experiment 4:
    Optical Aberrations    		 lab pics Melles Griot notes on aberrations and examples of spot diagrams;

    manual info on Code V software

    in the absence of this handy software, here is how it was done

    Week 6 14 May Experiment 5:
    Spectroscopy    		 lab pics Melles Griot notes on spectrometers and dispersing prisms.

    basics of spectrographs from James Graham

    Week 7 21 May Experiment 6:
    CCD Characteristics I.    		 lab and lab appendix pics Olympus applets illustrating how to build a ccd and photons interacting with silicon and ccd clocking schemes

    Part A ccd specs;
    Note that Part B of this lab can be a challenge due to necessity of a very old program interacting with a modern operating system.
    Part C ccd specs. and more recent version (that we don't have).

    Week 8 28 May Experiment 7:
    CCD Characteristics II.    		 lab pics Microscopy applet illustrating signal-to-noise

    Alta-U4000 camera info

    note on IRAF software along with explanation of the fits file format of the data and the iraf fits conventions

    Week 9 4 June Experiment 8:
    Infrared Camera and Spectroscopy    		 lab pics tutorial on infrared dectectors from Dick Joyce;

    Edmund Optics notes on infrared optical materials;

    IRC-160 camera info;

    atmospheric transmission in the near-infrared

    Week 10 11 June Complete and turn in experimental write-ups -- -- --

    This course was originally put together by Jim McCarthy and has been improved / modernized over the years by several others including Chris Martin, Chuck Steidel, Andrew Blain and Lynne Hillenbrand.

    Last Revised: 10 May 2012 by LAH