INTRODUCTION TO LASERS TECHNOLOGY EDUCATION SCARSDALE MIDDLE SCHOOL

Transcription

1 INTRODUCTION TO LASERS TECHNOLOGY EDUCATION SCARSDALE MIDDLE SCHOOL

2 Many of the pictures for this LASER presentation came from LASER PRESENTATION 2

3 LASER Originally LASER was an acronym for Light Amplification by the Stimulated Emission of Radiation. Now laser is a word used to identify this type of equipment or the light it produces. LASER PRESENTATION 3

4 The Atom Different electron orbits represent different energy levels. LASER PRESENTATION 4

5 The Electron Applying energy to an electron causes it to jump to a higher orbit. LASER PRESENTATION 5

6 The Photon When the electron drops back to its original orbit it releases a particle called a photon. Light is made up of photons. LASER PRESENTATION 6

7 Wavelength of Light Light moves in waves that are similar to ripples in water. Light is an example of electromagnetic radiation: It doesn t require a medium to pass through LASER PRESENTATION 7

8 Wavelength of Light 1 CYCLE Wavelength (λ): The distance the wave travels in one cycle. Frequency (f): The number of times a cycle repeats in one second (Hertz, formerley cycles/second). λ = c f LASER PRESENTATION 8

9 Wavelength of Light HERTZ λ ENERGY ~ 400 nanometers H I G H L E E R S S F R E E N Q E U R E G N Y C Y ~ 700 nanometers LASER PRESENTATION 9

10 1 NANOMETER IS ONE BILLIONTH OF A METER A human hair is about 80,000 nanometers in diameter. That s about 115 times the wavelength (λ) of red light. LASER PRESENTATION 10

11 Light Bulb Light is not focused Light is made up of many colors (wavelengths) Light is not coherent LASER PRESENTATION 11

12 White Light Light From A Light Bulb All colors (wavelengths). More longer wavelengths. Light is not coherent. Light is not focused. LASER PRESENTATION 12

13 Laser Light Light is very focused Light is made up of one color (wavelength) Light is coherent LASER PRESENTATION 13

14 Laser Light Light From A Laser One color (wavelength). Light is coherent. Light is focused. LASER PRESENTATION 14

15 Theodore Maiman First Ruby Laser 1960 LASER PRESENTATION 15

16 MIRROR How a Laser Works MANY PHOTONS ARE REFLECTED BACK AND FORTH BY THE MIRRORS AT EACH END OF THE ROD. MIRROR SLIT PHOTONS FROM EXTERNAL SOURCE STRIKE ATOMS ATOMS RELEASE MORE PHOTONS IN THE ROD. (STIMULATED EMISSION OF RADIATION) WHICH STRIKE OTHER ATOMS CONTINUING PHOTONS THE PROCESS (AMPLIFICATION). ATOM COHERENT, FOCUSED PHOTONS LEAVE THE ROD THROUGH A SLIT IN THE MIRROR. LIGHT AMPLIFICATION BY THE STIMULATED EMISSION OF RADIATION LASER PRESENTATION 16

17 Ruby Laser LASER PRESENTATION 17

18 Types of Lasers Based on the Material Used in the Laser Classes of Lasers Based on the Biological Damage the Laser Can Cause LASER PRESENTATION 18

19 Typical Lasers and Their Emission Wavelengths Laser Type Wavelength (nm) Argon fluoride (UV) 193 Krypton fluoride (UV) 248 Nitrogen (UV) 337 Argon (blue) 488 Argon (green) 514 Helium neon (green) 543 Helium neon (red) 633 Rhodamine 6G dye (tunable) Ruby (CrAlO3) (red) 694 Nd:Yag (NIR) 1064 Carbon dioxide (FIR) LASER PRESENTATION 19

20 Optical Damage Threshold Test NASA Research Center The Optical Damage Threshold test station at NASA Langley Research Center has three lasers: a high-energy pulsed ND:Yag laser, a Ti:sapphire laser and an alignment HeNe laser. LASER PRESENTATION 20

21 Classes of Lasers Based on the Biological Damage the Laser Can Class I: Cause Lasers that don t produce any harmful radiation. Class II: Lasers that are harmful if viewed for long periods of time. (The assumption is that people wouldn t let this happen.) Class III: Lasers that are dangerous for short exposure. (Many laser pointers are class III lasers!) Class IV: Lasers that can blind or burn after a very brief exposure. These can only be used under very controlled conditions. LASER PRESENTATION 21

22 LASER WEAPONS Do you expect me to talk Goldfinger? No Mr. Bond, I expect you to die. LASER PRESENTATION 22

23 Laser Gun Sights LASER PRESENTATION 23

24 Multiple Integrated Laser Engagement System MILES (2000) Laser Tag for Soldiers LASER PRESENTATION 24

25 Laser Targeting System Aircraft Mounted LASER PRESENTATION 25

26 Laser Guided Bomb ( Smart Bomb) Control surfaces Optical sensor Guidance system LASER PRESENTATION 26

27 Laser Targeting 2. Laser guided weapon tracks laser spot on target. 1. Laser targeting system paints target. LASER PRESENTATION 27

28 Laser Targeting System Ground Based LASER PRESENTATION 28

29 Laser Targeting Countermeasures AN/VVR-1 Laser Warning Receiver System System detects the targeting laser. Countermeasures include smoke, brighter laser beam, maneuvering, etc. LASER PRESENTATION 29

30 Laser Guided Missile Hellfire laser guided missiles mounted on a US Army Apache helicopter gunship. Newer variation (Hellfire II) replaces laser guidance with radar guidance to penetrate smoke and cloud cover. LASER PRESENTATION 30

31 ABL Airborne Laser Antimissile Weapon United States Air Force LASER PRESENTATION 31

32 ABL Nose Turret CO 2 Targeting Laser LASER PRESENTATION 32

33 LASERS IN MANUFACTURING

34 Punch Press Typical Stamped Parts Punch Press Problems Dangerous to operate. Required long runs to be profitable. LASER PRESENTATION 34

35 Laser Cutter LASER PRESENTATION 35

36 Computer Control of Laser Cutter Equipment No human contact with the part during operation. Computer program can be loaded quickly. Shorter runs are now profitable. LASER PRESENTATION 36

37 Laser Welding Welded Parts LASER PRESENTATION 37

38 Laser Welding Welded car door panel made from three types of steel. LASER PRESENTATION 38

39 Laser Stereolithography (SLA) LASER PRESENTATION 39

40 Part Produced by SLA LASER PRESENTATION 40

41 LASERS IN MEDICINE LASER PRESENTATION 41

42 Laser Eye Surgery LAser in SItu Keratomileusis (Lasik) 2. Laser removes tissue from remaining cornea to change its shape. 1. Tiny flap of outer cornea folded back. 3. Flap of outer cornea then reattached. LASER PRESENTATION 42

43 Laser Tattoo Removal (Doesn t always work!) The laser beam breaks up the pigments in the tattoo into small particles. Then the body s immune system attacks and destroys them. LASER PRESENTATION 43

44 Laser Dentistry Laser Water jet Major advantage is no drilling sound. Can t be used on existing metal fillings. LASER PRESENTATION 44

45 LASER TESTING AND MEASURING LASER PRESENTATION 45

46 Laser Bar Code Scanning Universal Product Code (UPC) Label LASER PRESENTATION 46

47 Barcode on a UPS Label LASER PRESENTATION 47

48 Barcode Scanner LASER PRESENTATION 48

49 Railroad Car Sorting Using Barcode Scanning Labels were often too dirty for the scanners to read. LASER PRESENTATION 49

50 Laser Surface Roughness Tester LASER PRESENTATION 50

51 Laser Level LASER PRESENTATION 51

52 Laser Speed Measurement New York State Police LASER PRESENTATION 52

53 Telescope Calibration Lick Observatory The adaptive optics system at the Shane 3 meter telescope utilizes a 20-watt sodium laser to put a false star in the sky. The system uses the star to compensate for atmospheric disturbances, creating sharper, clearer images of the objects observed. LASER PRESENTATION 53

54 LASER COMMUNICATION LASER PRESENTATION 54

55 Laser Printer Corona Wire Discharge Lamp LASER PRESENTATION 55

56 Laser Disk Pit Land Beam doesn t reflect: logical 0. Beam reflects: logical 1. LASER PRESENTATION 56

57 Laser Disk Drive LASER PRESENTATION 57

58 MODULATION Superimposing a weak signal on a strong one Audio MODULATED LASER BEAM: Changes in the beam represent information in the audio signal. Laser Carrier MODULATOR: Combines audio signal and laser beam. DEMODULATOR: Removes audio signal from the modulated laser beam. LASER PRESENTATION 58

59 FIBER OPTICS Transparent Pipe for Light to Travel Through Advantages: Very high capacity. Can t be tapped into. Not affected by electromagnetic (EM) interference. Allows light to travel around corners. Disadvantages: Expensive. Can be difficult to install. LASER PRESENTATION 59

60 Fiber Optics Center fiber optic cable has greater capacity than any of these bundles of cable. LASER PRESENTATION 60