Laser information and colour wavelength notes

Laser information and colour wavelength notes

Basic information about lasers:
A laser is a device that emits light through a process of optical amplification based
on the stimulated emission of electromagnetic radiation.

Lasers can also have high temporal coherence which allows them to have a very narrow spectrum,
that is, they only emit a single color of light.

Laser pointers normally have wavelengths in between 400 and 700 nm.
 The visable spectrum

Laser beams can be seen from a far distance.
Laser dots on objects or structures can be seen from a far distance.

Laser uses:
Laser pointer
Lasers can be mounted on firearms
Optical disk drives
Laser printers
Barcode scanners
Fiber optic and free-space optical communication
Laser alarm
 For example when the laser beam is touched
 the alarm goes off.
Cutting
Welding
Medicine
Thermometers
Measuring range and speed
Laser lighting displays

Types of lasers and operating principles:
Gas lasers
Chemical lasers
Excimer lasers
Solid-state lasers
Fiber lasers
Photonic crystal lasers
Semiconductor lasers
Dye lasers
Free-electron lasers

Lasers and power examples:
1-5  mW  : Laser pointer
5-40 mW  : Lasers
45 mW -  : Lasers and Hobby burning lasers
300 mW      Some burning lasers are made out of laser pointers
            that are made stronger.
            Some burning lasers are made from a laser diode
            gotten out of a DVD-RW drive.
            You might need more then 45 mW to pop a baloon.
100-3000 W: Industrial laser cutting

In some countries lasers above 5 mW are only legal for, for example companies and industrial purposes or
hospitals and medical purposes.

Laser warnings:
Lasers can be damaging to the eyes.
 Even weak laser pointers can be damaging to the eyes.
 There are laser safety goggles to protect the eyes
 Adviced when working with certain powers and wavelengths.
Hobby burning lasers can also be damaging to the epidermis.


Colour wavelengths:
There can be some difference in data when compared to other information about colours and wavelengths.
 For example you also have the naming bleu-violet and yellow-orange as for example orange comes after
 yellow in the wavelength spectrum when going to higher wavelength numbers and in between those two colours
 it becomes hard to say what wavelength belongs to exactly what colour.

Datas shown here are approximates.

UV
Wavelengths:
 238 nm to 400 nm

Blue-Violet
Wavelengths:
 405 nm to 425 nm

Bleu
wavelenghts:
 435 nm to 490 nm

Cyan
Wavelengths:
 490 nm to 512 nm

Green
Wavelengths:
 520 nm to 565 nm

Yellow
Wavelengths:
 565 nm to 590 nm
 
Yellow-orange
Wavelengths:
 Around 593.5 nm is a bit orange and is mostly called a yellow-orange laser

Orange
Wavelengths:
595 nm to 620 nm

Red
Wavelengths:
 622 nm to 720 nm

Infrared
Wavelengths:
 785 nm to for example 1342 nm


Extra information 1:
Nm = Nanometers
One meter equals 1,000,000,000 nanometers.
One nanometer is about the length of ten atoms in a row.

Extra information 2:
A typical human eye will respond to wavelengths from about 390 to 700 nm.

Extra information 3:
Lasers emitting visable wavelengths below 445 nm appear violet to the human eye, a distinctly different color.

Extra information 4:
308 nm to 364 nm: near ultraviolet
238 nm to 284 nm: far ultraviolet
700 nm to 1350 nm  : near infrared
1540 nm for example: far infrared

Extra information 5:
Frequency = Terahertz (one trillion cycles per second)
Bleu with a wavelength of 450 nm has a frequency of about 670 THz
Red with a wavelength of 627 nm has a frequency of about 478 THz