1.1: Pre-lab Exercises

Safety, Polarization States of Optical Waves, Dielectric Reflection and Geometric Optics

The Pre-Lab Exercises must be completed BEFORE entering the Lab. In your lab notebook record data, explain phenomena you observe, and answer the questions asked. Remember to answer all questions in your lab notebook in a neat and orderly fashion. No data are to be taken on these laboratory sheets. Tables provided herein are simply examples of how to record data into your laboratory notebooks. Expect the in-lab portion of this exercise to take about 3 hours.

PL 1.1 - Safety

Read the entire Laboratory and laser Safety Packet that was handed out in the classroom. Be prepared to answer questions about high-voltage and laser safety before arriving at the MOL.

PL 1.2 - Get Prepared to Start the Laboratory Exercises 

Read the entire laboratory handout, and be prepared to answer questions before, during and after the lab session. Determine all the equations and constants that may be needed in order to perform all the laboratory exercises. Write them all down in your laboratory notebook before entering the Lab. This will ensure that you take all necessary data while in the Lab in order to complete the lab write-up. This preparatory work will also count toward your Lab Exercise grade.

PL 1.3 - Telescope Design

For this exercise, you are encouraged to work in groups of 2-3 people. In this exercise, you are to design a telescope given the optical components listed in Table I. Your telescope must be a refractor (lenses-only). The entire telescope assembly must not be any longer than the 2 feet (the shorter, the better). Your telescope will need to contain at least 2 optical elements, but no more than 4. The telescope must be a terrestrial telescope (meaning that the image as seen by a viewer must be erect). Your total system magnification must be at least 4x and at most 40x at an imaging distance of either 15 meters or adjusted to infinity (a collimating telescope – this is the most common form of telescope, and is preferred for simplicity and robustness of design). Be sure to use the ABCD matrix approach to simplify the design of your telescope. You should include all of your system specifications in the pre-lab write-up – including any computer code, hand-calculations or other materials used in the design. Be sure to specify the focal lengths, total system magnification as well as the locations of the lenses, the object and the image. Remember, there is no one ‘correct’ way to design your telescope. The Lab staff will be very sad if everyone designs the same telescope. Additional points will be awarded for ingenuity and thoughtfulness in design. Also, be sure not to use too many elements; each additional element in your system will lead to decreased contrast and decreased resolution. “Ingenuity and thoughtfulness” means designing smart, and minimizing complexity.

TABLE 1. Optical elements available for building your telescope:

Size	Type	Focal Length	Quantity
2''	Bi-Convex	200 mm	1
2''	Bi-Convex	100 mm	2
2''	Bi-Convex	75 mm	1
1''	Bi-Convex	200 mm	1
1''	Bi-Convex	150 mm	1
1''	Bi-Convex	100 mm	1
1''	Bi-Convex	75 mm	1
1''	Bi-Convex	50 mm	1
1''	Bi-Convex	35 mm	2
1''	Bi-Convex	25.4 mm	2
1''	Bi-Concave	-100 mm	1
1''	Bi-Concave	-75 mm	1
1''	Bi-Concave	-50 mm	1
1''	Bi-Concave	-25 mm	1

Hints: Remember to use larger lenses at the input of your system (the side facing the world), and smaller lenses close to the eye. Also, before you start designing, determine which element in the ABCD matrix must equal zero for angular magnification to occur.

PL 1.4 - Extra Credit (Not Required) 

Design a zoom-optic system with the components listed above. (With a zoom-optic system, you can adjust the magnification of your telescope by moving a central lens while keeping the outer most lenses at approximately the same location – basically the same setup as is used in an SLR camera zoom lens.)

“Two brothers bought a cattle ranch and named it "Focus." When their father asked why they chose that name, they replied: "It's the place where the sons raise meat." -- Prof. W. B. Pietenpol, Physics Department, University of Colorado, Boulder, Colorado