Laser Technology Basics - Level 1

1. Science and Data Acquisition LASER Technology Basics – Level 1

2. What You’ll Learn… • The safety rules for using lasers • How to measure and compare the output power of your laser to other light sources • Characteristics of laser light waves and how wave interference can create laser light patterns. Stuff You’ll Need… • LASER and its power adaptor • Photometer/receiver (speaker) with power adaptor and a stand to mount the detector on • Danger sign from your kit

3. ePortfolio Suggestions… • Add a list of laser safety rules to your ePortfolio • Take action photos of your experiments • Make a short video giving the name each component in your laser communications kit and where it is stored • Keep daily notes on any problems you encountered and how you solved them • Document troubleshooting tips for the next team

4. What You Should Know… • It is very important that you know and follow all the LASER safety rules to prevent injury • Do not operate the LASER at a level where it could accidentally hit someone in the eye. Keeping the LASER close to the floor is safer than having it at desk level. Floor level will usually only hit people’s feet. Desk level could hit someone in the eye. • How to handle the LASER equipment carefully to prevent accidental damage to the equipment • How to properly store the LASER communication equipment when you are finished for the day

5. What You Should Know… • Laser safety is the avoidance of laser accidents, especially those involving eye injuries. Since even relatively small amounts of laser light can lead to permanent eye injuries, lasers are subject to official regulations and they are classified. • Lasers have been classified by wavelength and maximum output power into four classes and a few subclasses since the early 1970s. The classifications categorize lasers according to their ability to produce damage in exposed people, from class 1 (no hazard during normal use) to class 4 (severe hazard for eyes and skin). There are two classification systems, the "old system" used before 2002, and the "revised system" being phased in since 2002. • Learn more online… http://en.wikipedia.org/wiki/Laser_safety

6. What You Should Know… These are the parts that make up your SmartLab Laser Collection AM-FM Radio The Diode LASER Optics Kit Fog in a can Stands Photometer Receiver Please help keep things organized! Laser Power Adaptor Speaker Power Adaptor

7. Magnifying Glass Audio Patch Cords Audio Patch Cord for Radio Batteries Prism Dividers Microphone Front Surface Mirror Comb and Rubber Bands Diffraction Glasses

8. 3 Front Surface Mirrors LASER Leveler Fiber Optic Sample Kit 3 Leveling Posts Security System Unit LASER Leveler goes here Security Power Adaptor Tripod

9. Do It!Examine the LASER This is the laser you will be using for all your laser communication experiments. Study the photos below to see how you connect the laser. Audio Cable ON - OFF 635 nm Diode Power Adaptor Shim for adjustment Laser Back View Laser Side View

10. Do It!Examine the LASER What kind of laser do you have. Read the yellow label on the side of your laser. Is it the same as the label you see here? You can learn three things by reading your label. It tells you the laser type, its maximum power output, and the classification of your laser. Read your Label 635NM Diode Laser Side View

11. Do It!Examine the LASER Your laser has a copper shutter to block the path of the laser beam as an added safety feature to prevent accidental shining of the beam even when the laser is on. Open the shutter when you are ready to send the beam. Close the shutter when you want to block the beam. 635 NM Diode Beam is NOT Blocked Beam Shutter Lever Beam is Blocked Laser Front View Shutter Closed View Shutter Open View

12. Do It!Measure Laser Power Now that you know a little more about laser safety and classification systems, you might be wondering how powerful your laser is. You can find out by setting up and doing this experiment. The photometer measures the intensity of the light that is hitting the detector sensor. This experiment is explained on page 7 in your Introduction to Lasers student guide. Power Adaptor Detector on a Stand Detector on a Stand Photometer/Receiver (speaker) 3-5 feet .890 LASER Power Adaptor

13. Do It!Measure Laser Power 1 Aim your laser beam on the detector sensor 3 Write this number on your Caution Sign 2 Set the dial to 2mW (2 milliwatt)

14. Do It!Complete and Display Sign Now fill in the blanks on your Danger sign. If someone else has already done it, just make sure they did it right, and then display the sign anytime you are using the laser. Use your label and your power reading

15. Do It!Laser Speckle Patterns Note: Not everyone will see the same thing. Ask everyone to be perfectly honest in sharing what they see in the bulb. You will need a frosted or “soft white” incandescent light bulb for this experiment. Place the light bulb in something to hold it stationary (a cup, a cone of clay or something) and aim the laser beam into the center of the bulb. It helps to turn the lights out. View the light bulb from an angle (be careful NOT to look straight in line with the laser beam). Describe what you see. Ask some classmates to try it and describe what they see. Power Adaptor Wow, I can see the bulb full of tiny floating red speckles, and they move when I move my head LASER Lid off a can of spray paint

16. Do It!Laser Speckle Patterns Why do you see red dots? Do you think that the light bulb is shattering the laser beam into thousands of little tiny pieces inside the bulb? Most people will see a cloud of bright red sparkling specks floating in the glowing red bulb. Move your head side-to-side and then up and down. What happens to the red dots when you do that? Ask some classmates to try it and describe what they see. The dots are moving with the motion of my head. Power Adaptor LASER The dots are moving opposite to the motion of my head.

17. Do It!Laser Speckle Patterns SAFETY TIP: Keep your back towards the laser while you are looking at the dot patterns Do you have a magnifying glass? If you do, try using it to enlarge your laser beam as you project it on the wall. Look closely at the red dot area on the wall to see if you detect laser speckle. It won’t be quite as dramatic as the light bulb method, but it still works pretty well. I can see a cluster of tiny floating specks, some dark and some sparkling bright Power Adaptor LASER

18. Do It!Laser Speckle Patterns What you are seeing is known as laser speckle. Laser light is different from ordinary light in two ways: It is mono-chromatic (one color) and coherent. Coherent means that all the peaks and troughs of the light wave line up over very long distances. When laser light scatters off of surfaces, these peaks and troughs can interfere with each other to produce bright and dark spots. If the surface is regular, one sees a diffraction pattern. If the surface is random and diffuse, one sees laser speckle. You can learn more about laser speckle online. Try your favorite search engine and see what you can find. Incoherent Light Waves Coherent Light Waves

19. Do It!Laser Speckle Patterns SAFETY TIP: Keep your back towards the laser while you are looking at the dot patterns Try this experiment, but remember to never look directly back into the laser beam. Fold a white piece of paper like an accordion. See if the irregularity of this surface changes the speckle pattern. Try catching the beam with a flat piece of paper in your hand. Try holding the paper in your hand and rotate it to different angles to make the beam even wider. Do you still see a speckle pattern? Try this with flat paper and the folded paper. Power Adaptor LASER

20. Do It!Laser Speckle Patterns You will still see the speckles, but are they 2D or 3D when you have one eye closed? Have you noticed how the dot patterns seem to hover above the surface of the paper, and they have kind of a 3D dome shape like tiny jelly particles floating over the paper. Try closing one eye to see how that changes the image you see. Switch eyes and move your head side-to-side. What changes did you observe? I can still see the speckles, but they are different. Dots hover in a dome shape Power Adaptor Side View LASER

21. Do It!Laser Speckle Patterns When you switched from two eyes to one eye it effected your ability to see things in three dimensions (3D). You need both eyes to enable your brain to compose a 3D image and give you depth perception. If you are having trouble seeing 3D, this might mean that you might have problems with your binocular (two-eyed) vision or stereo vision (3D vision). Get ready to extend your understanding of how your eyes and brain work together to enable you to see things in 3D

22. Extend YourselfLearnHow We See 3D Each eye captures its own view and the two separate images are sent on to the brain for processing. When the two images arrive simultaneously in the back of the brain, they are united into one picture. The mind combines the two images by matching up the similarities and adding in the small differences. The small differences between the two images add up to a big difference in the final picture! The combined image is more than the sum of its parts. It is a three-dimensional stereo picture. The word "stereo" comes from the Greek word "stereos" which means firm or solid. With stereo vision you see an object as solid in three spatial dimensions--width, height and depth… or x, y and z. It is the added perception of the depth dimension that makes stereo vision so rich and special. Learn More… http://www.vision3d.com/stereo.html Do the framing game! http://www.vision3d.com/frame.html