1. Lasers!!
By: Julia Bowman
Science pg

2. Quiz!! To see if you read #1)What is holography?
#2)When was the first barcode reader used?
#3)How do carbon dioxide lasers treat gum disease?
#4)What is photolithography?
#5)What is stereolithography?

3. Quiz answers
#1)Holography is the method of producing a 3D recording of an object.
#2)The first barcode reader was used in 1974.
#3)Carbon dioxide lasers treat gum disease by removing swollen tissue.
#4)Photolithography is the laser process of integrated circuits that are made of patterned layers and semiconductor material.
#5)Stereolithography is a laser technique that relies on the fact that some liquids turn to solids when it is exposed to ultraviolet light.

4. Laser dentistry
Lasers can be used to "drill" teeth with solid-state erbium lasers that emit 3-µm wavelength light.
Lasers can't remove enamel well but can prepare cavities for repair.
Laser pulses are less threatening than traditional dental drills.
Carbon dioxide lasers can help treat gum disease by getting rid of swollen tissue.
Lasers can also be used for teeth whitening by applying a certain gel to their teeth.

5. Laser drilling
It is accomplished with 1 or more short pulses, which remove materials.
The number of pulses is dependent on wavelength, peak power, the nature of the material, and repetition rate.
These can be powerful enough to drill holes in diamonds!

6. Laser cutting
This is usually accomplished with a jet of air, oxygen, or dry nitrogen's assistance.
Good for cutting wood, paper, and plastic, but thicker materials are harder. Typically, chars food when a laser cuts it. 
The process of cutting metals with lasers is called "laser- assisted cutting", because the oxygen is responsible of for the process that causes the cut.
Carbon dioxide lasers are commonly used for cutting.
Laser cutting is much faster and efficient than mechanical cutting.

7. Laser beam welding
Welding is the opposite of cutting; welding joins two materials together using heat.
To form a solid bond you have to fit them together perfectly.
The heat transforms the metal through the depth of the weld, and in a zone extending on the sides of the junction.
The materials that are welded must bond to each other well.

8. Laser marking, engraving, & etching
Lasers can be used to leave a permanent mark on a material.
Laser engraving uses a high-power laser to efficiently "drill" an indention in the surface of a material.
Laser engraving is commonly used to mark serial numbers or logos on products.
Laser etching is a subset of laser engraving; etching causes raised marks on a material.

9. Photolithography
These integrated circuits are made of patterned layers of a semiconductor material and are a part of a laser process called photolithography.
Steps: 1- Coat the surface of a semiconductor wafer with a light-sensitive material (photoresist). 2- Apply to ultraviolet light. 3-Depending on the type of photoresist the exposed or unexposed areas will be etched away. 4- Repeat (if needed)
This improves ArF technology, which is an important goal within the laser industry.

10. Stereolithography
Stereolithography is a laser technique that relies on the fact that some liquids turn to solids when it is exposed to ultraviolet light.
Selective laser sintering- a process in which a high-power laser beam is scanned to melt small particles in a powder that covers a small platform.
Stereolithography systems are commercially available to certain people.

11. Barcode Readers
Barcode readers is a familiar form of laser technology.
They scan the dark lines of varying thickness, the dark lines absorb the light and the white spaces reflect the light.
A photodiode measures the intensity and interprets it as a string of information.
Ex: When you check a book out from the library and you scan the barcode.
The 1st barcode reader was used in 1974.

12. Laser pointers
Laser pointers are most commonly used to highlight certain objects during a presentation, but they have other uses. Constuction companies use laser pointers as a part of surveying or leveling purposes. Robotics use laser pointers to direct the robot.
They are often misused. Even though the low-power laser can cause eye damage.

13. Laser printers
Laser printers use a laser beam to guide ink on the paper.
Ex: Whenever you press the "print" button on your computer it sends a stream of data to the laser printer, that uses a laser beam to guide the ink.
In 1969, Gary Starkweather developed the idea of laser printing. Laser printers used to be expensive and bulky. Now, laser printers are more efficient, higher-quality and affordable.

14. Optical discs: cds, dvds, and others
CDs and DVDs are made of three layers a plastic base, containing the information, a reflective aluminum layer, and a transparent polycarbonate layer that protects the track information.
The LaserDisc was introduced in It was a higher quality alternative to VHS tape.
CD players used wavelengths of 780nm. DVD players used wavelengths of 650nm.
DVDs could store up to 30 times more information than CDs.
Bluray discs store up to 10 times information as DVDs, that's 300 times as a CD.

15. holography
Holography is a method of producing a 3D recording of an object.
Holograms are not an image itself and most of the time cannot be seen under normal lighting.
Holograms require laser lighting for the recording and viewing the hologram.
A hologram is formed when you split a laser beam into two separate beams, one illuminates and scatters off the object to be recorded.
Dennis Gabor was awarded the Nobel Prize for Physics in 1971 for the invention of holography.

16. Quiz!! To see if you listened
#1)Who won the Noble Prize in Physics for creating holography?
#2)True or False: CDs hold more information than DVDs.
#3)Is laser beam welding the same as laser cutting?
#4)Can lasers remove enamel?
#5)Who developed the idea of laser printing?

17. Quiz answers
#1)Dennis Gabor won the Noble Prize in Physics for holography.
#2)False
#3)No, they are opposites.
#4)No, but they can prepare cavities for repair.
#5)Gary Starkweather developed the idea of laser printing.