# HOL Pre-Lab

## Contents

INCLUDE THIS SHEET AS THE FIRST PAGE OF YOUR REPORT

Student's name ______________________________________________________________

Partner's Name ______________________________________________________________

# Pre-Lab Discussion Questions and Sign Off Sheet

It is your responsibility to discuss this lab with an instructor before your first day of your scheduled lab period. This signed sheet must be included as the first page of your report. Without it you will lose grade points. You should be prepared to discuss at least the following before you come to lab:

1. What is a hologram? Students often respond that a hologram preserves 3-D information while a regular picture only contains 2-D information. That statement is too vague. Specifically, what “extra” information is contained in the diffraction pattern that makes up a hologram? How is it encoded? For example, what does the diffraction pattern caused by a plane wave (the reference beam) interfering with light from a point source (a simplified object) look like? See figure. How does this pattern change as the point source changes position (x, y, z)?
2. How does the Michelson interferometer work? In the interferometer shown, the lengths L1 and L2 are different. What is the path difference between the light waves that are sent along the two arms when they recombine at the screen?
3. Concerning the laser: a. The coherence length is a characteristic length of the wave trains emitted by the laser. Physically, what does this length tell us about the light from the laser? Why is this an important number to know? How might you measure it? b. The laser light is very bright or intense, with a diode laser power of 45 mW in a collimated beam. Compare this to the power of the sun at the earth’s surface (check the CRC Handbook. The solar constant is 2 calories/cm2/minute). How do the spectral powers compare (power/wavelength interval)?
4. What are the safety requirements for working with this Laser?

Staff Signature ______________________________________________ Date ____________

Completed on the first day of lab? (circle) Yes / No

# Mid-lab Questions

On day 3 of this lab, you should have measured the stability of the laser and successfully produced a transmission hologram. Show them to an instructor and ask for a signature.

Staff Signature ______________________________________________ Date ____________

Completed by the third day of lab? (circle) Yes / No