Home Page of the Lectures "330: Modern Experimental Optics", Fall 2006

Georg Hoffstaetter

(607)255-5197, 118 Newman Lab, Georg.Hoffstaetter@cornell.edu
(607)254-8981, 226 Wilson Lab, www.lepp.cornell.edu/~hoff
Teaching Assistant: Andrew Noble
(607)255-5722, Newman Lab, an76@cornell.edu

Literature Dates
Quizzes and Final Exam
Academic Integrity

08/ 28/ 06
405 Clark Hall
First laboratory
We 08/ 30/ 06 132 Rockefeller Hall
First lecture

10/ 07 - 10/ 10 No lab on 10/09 and 10/10
Fall break
11/ 28/ 06 405 Clark Hall Last laboratory
11/ 29/ 06
132 Rockefeller Hall
Last lecture
Th 12/ 07/ 06, 2pm 127 Rockefeller Hall Final exam
Mo 13:25 - 16:25 405 Clark Hall
13:25 - 16:25 405 Clark Hall
12:20 - 13:10 132 Rockefeller Hall

Before new experiment

Lab reports due
Tu 12:00-13:20 118 Newman Lab Office hours, Prof. Hoffstaetter

Newman Lab Office hours, TA


Related material:

Lab Description

The following 6 subjects will be covered. A laboratory report has to be produced for each one of them.

1) Reflection and Refraction

To work on during 08/28/06-09/12/06: Erik & Pui @ table 1, Yang & Se @ table 2, Abbie & John @ table 3
To work on during 09/18/06-09/26/06: Joshua & Jacqueline @ table 6

As preparation, read Hecht chapter 4, especially section 4.3, 4.4, 4.5, 4.6 and 4.7, and of course read the lab manual for experiment 1.

2) Polarized Light

To work on during 08/28/06-09/12/06: Pisut & Joshua @ table 4, Soham & Amy @ table 5, Avtar & Jacqueline @ table 6
To work on during 09/18/06-09/26/06: John & Erik @ table 1, Abbie & Yang @ table 2, Amy @ table 5

As preparation, read Hecht chapter 4, especially section 4.6 and chapter 8, especially section 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, and 8.7, and of course read the lab manual for experiment 2.

3) Geometrical Optics

To work on during 10/02/06-10/23/06: [Abbie @ table 1, Amy @ table 2], [Erik @ table 3, Jacqueline @ table 4], [John @ table 5], [Joshua & Yang @ table 6]

As preparation, read Hecht chapter 5, especially section 5.1 to 5.5, and of course read the lab manual for experiment 2.

4) Interference

To work on during 10/24/06-11/06/06: [Erik @ table 1, Amy @ table 2], [Abbie @ table 3, Jacqueline @ table 4], [Joshua @ table 5], [John & Yang @ table 6]

5) Fresnel and Fraunhofer Diffraction

To work on during 11/07/06-11/20/06: [John @ table 1, Amy @ table 2], [Yang @ table 3, Jacqueline @ table 4], [Abbie @ table 5], [Joshua & Erik @ table 6]

6) Fourier Optics

To work on during 11/21/06-11/28/06: [Joshua @ table 1, Amy @ table 2], [John @ table 3, Jacqueline @ table 4], [Yang @ table 5], [Abbie & Erik @ table 6]

08/28/2006: 1st lab session - Today you will identify the provided equipment, complete the equipment inventory, and align the laser on your optical bench. The lab benches with odd numbers (1,3,5) will start setting up experiment 1. The others will set up experiment 2.
08/29/2006: 2st lab session - Most of you made good progress on labs 1 or 2. I saw some loose papers in stead of log books. Please buy good notebooks to keep you log.
09/04/2006: 3rd lab session - We covered error propagation, some derivations were formal, please review them. We will have several examples to illustrate the points during the class.
09/05/2006: 4th lab session - Note that the razer blades are useful for finding the beam centroid, better than a paper card. If your multimeter shows numbers, but they do not change with light intensity, please replace the batteries of your amplifyer. You need the small batteries on the front table. We discussed how to use the beam splitter to measure reflectivities for close to normal incidence. This technique can also be used in experiment 2 for confirming Fresnel's equations.
09/11/2006: 5th lab session - When you are using an optimum (maximum or minimum) of transmitted light to measure a quantity, for example the angle of a polarizer, or the orientation of a mirror, you will obtain a bad precision of that angle, because at an optimum the intensity changes little with these parameters. You obtain significantly better precession by measuring several points around the optimum, and than fitting a parabola to determine the location of the minimum. The group of experiment 1 impressed by finding that the last measurement of n used an incorrect formula in the manual. It did not consider the infinite series of back-reflections within the prism. After this infinite series was computed, the measurements matched this new formula quite well. Congratulation guys! The manual will be changes. As far as I understand this has gone unnoticed for years! I found this lab session very enjoyable, a reflection of what real laboratory work often is like. You find unexpected results during your measurements, and that leads you to a deeper understanding of the physics involved.
09/12/2006: 6th lab session - Everybody was very busy and eager to collect all data needed to submit the lab report in a week. I had several questions about the lab reports, some of them in email conversations. Please note that it is better to work with the advice from this web page, because the manual will be changed. I have included my comments in these conversations to the lab report suggestions on this page below. One general comment: There is no cookie cutter recipe for a scientific report. Always try to envision which ordering of material would most help you as a reader to grasp the information.
09/19/2006: 7th lab session - Several people found that this lab required more work than anticipated and dropped the class. The tables above reflect this change.
09/20/2006: 8th lab session - You are all on a good schedule to finish lab 1 and 2. But of course you are waiting for a blue ski to use the polarizer. In the lab reports, you all use n=1 for air. You should at least make an argument why the deviation from 1 leads to an error in your result that is much smaller than the other errors of your experiment. Some of your abstracts do not contain the information needed to give the reader a good overview of the report's purpose. Please read again the lab report section below and take a look at the linked example paper.
9th lab session - I observed good progress for everybody. You are able to handle the lab material much faster now that you are used to the equipment, and you will easily finish this experiment in 4 sessions, although the previous experiment required 6 sessions.
09/27/2006: 10th lab session - above at 09/11/06 it is discribed that parameters at a minimum of some measurable quantitiy should be obtained by measuring a curve to both sides around the minimum. To determine the error of the minimum, you can use your eye. You draw all you points with error bars on a graphing paper (or a computer printout) and draw a parabola as far to the left as is reasonably consistent with the error bars and as far to the right as is reasonably consistent with your error bars. This visual method allows you to estimate an error for your minimum. After all, the errors for your points on the curve are also only estimated. This sounds vague, and indeed it is vague. A more careful error analysis can be done, but it is somewhat complex and I do not expect you to do this in your report.
10/09/2006: No lab today
10/10/2006: No lab today
11/26/2006: Note that in the class evaluation there is a question about quizzes before each experiment. We did not have such quizzes, so please enter "does not apply."
Today was the last lab, and you have all finished your measurements. The last lab report will be due on Tuesday, December 5.
Today was the last lecture. Because of student request, the lecture notes are linked here. Have fun!

Lab report

The structure of your lab report should follow these guidelines:

   1. Title
   2. Author
   3. Abstract
         1. Describing the goal of the experiment
         2. The method used for achieving it
         3. A short summary of the results
         4. A list of especially interesting findings
   4. Introduction
         1. Describing the background of the topic being investigated. Why is the goal of the experiment of interest?
         2. How have similar measurements been done in the past, why is it done again here?
         3. Include general theory, meaning theory that does not only apply to your experiment. For experiment 1, for example, the introduction should mention Snell's law.
   5. Theory
         1. Review of the theory that is used in the experiment. Here you should use some judgment on whether a theory is very general and should be in the introduction, or whether it is more special to the experiment, and should therefore be in this section. The theory of Fresnel's equations is general and should be in the introduction. Brewster's angle is a corollary of that theory and could therefore also be in the introduction. However, you could also take the view that it is the specific corollary that you use for experiment 2, and you could therefore put it into this theory section.
         2. Derivation of general formulas that will be used. For experiment 1C, for example, this would include the derivation of how n is related to the minimum angle of refraction. For experiment 2, for example, the last equation in the manual with tan over sin to get the difference between the phase advances in the overhead transparency should be derived here. But as I said in class, it might be a challenge to derive it without help, so you do not have to include a derivation. For this time, just reference the lab manual. But describe well which angles have to be used in for this formula.
   6. Experimental setup and results
         1. Graph of setup. For experiment 1C, for example, you could describe how the prism is mounted and how you measured the minimum angle.
         2. Quantities measured'
         3. Sources of errors
         4. Data and their errors in graphs
         5. Data evaluation leading to the measurement result and its error estimate
         6. Error analysis. Complex formulas for the error analysis should be in an appendix
   7. Conclusion
         1. Summary of results
         2. List of especially interesting findings
         3. Suggestion of improvements or how to continue the work
   8. Acknowledgments

Example paper

Quizzes and Final Exam

Before you can start your experiment, you have to read the relevant sections of this manual and of the textbook by Hecht. Then you have to pass a short oral quiz in the laboratory. Furthermore you must hand in the report of your previous experiment. The final exam covers the material that was covered in class as well as the experiments.

Auxiliary material for the final exam

1. One handwritten page of formulas
2. No computers, but calculators
3. No lab manual
4. Book: Optics by Hecht
5. No cell phones


Prerequisite physics courses at Cornell: Physics 214 or Physics 218

List of math courses at Cornell.
Mathematical topics that will be useful for this laboratory: Complex functions, Taylor Series, Vectors, Fourier Series, Linear algebra.


The laboratory reports are due before a new experiment can be started. They account for 85% of the grade. The lab reports are due one week after the completion of the experiment. The grade of unexcused late reports will be reduced by 10% per week. The final exam is worth 15%. Each laboratory report will be graded according to the following scheme: Each experiment will be separated into 5 sub-experiments, and for each sub-experiment 4 points can be obtained for "Theory", "Experimental Description", Data Taking", and "Evaluation." In addition 10 points can be obtained for "Performance in the lab" and for "Quality of the Report." This sums up to 100 points per report.

Academic integrity

Academic Integrity is mandatory.

Basic principle: Do not pretend that the work or ideas of others are your own.
1) You may discuss the experiments with others.
2) You have to credit documents or people if you have used their ideas.
3) You may not copy equations, derivations, or text from other laboratory reports.

Send comments to G. H. Hoffstaetter

Last Update: 12-08-2006