Laser Marking 101

In determining the right laser marking systems to meet your manufacturing and part marking requirements it is important to understand the basics of laser marking. MECCO's years of experience with laser marking equipment and systems allows us to share our expertise and knowledge and has created the Laser Marking 101 presentation.

What is a laser?

It's simply the Light Amplification by the Stimulated Emission of Radiation!

Now what does that mean and how does that happen?

Every object in the universe is made up of atoms. These atoms are constantly in motion; vibrating, moving and rotating. Atoms can be in different states of excitation; either ground state or excited level.

In order for an atom (electron) to reach an excited level some type of energy must be applied via heat, light or electricity.

Once an electron moves to a higher-state, it wants to return to its original state. When it does, it releases its energy as a photon a particle of light.

These photons of light are what we use in lasers. Although there are many types of lasers, they all have certain essential features. Either a rod or a gas tube is excited by light or electricity (flash lamp, diodes or RF frequency) to release photons of light.


Laser in non-lasing state		Light from lamp excites atoms

Some atoms emit photons		Photons bounce back and forth on mirrors stimulating the emission of other photons; laser beam out one end

Types of Lasers

Fiber Laser (Ytterbium) 1070nm
CO2 Laser (gas laser)
Nd:YAG Flash Lamp Laser (solid state)
Nd:YAG Diode Laser Pumped
Vanadate (Nd:YVO4)

Fiber Lasers

The fiber laser features the latest in laser marking technologies, fiber pumping. The laser resonator consists of a fiber bundle that is doped with Ytterbium and pumped with light emitting diodes. The laser light is then fiber delivered to the optical head that consists of a beam expander, collimating optics and back reflection protection.

Benefits of a Fiber laser system:

Available in 10 and 20 Watt models
Fiber diodes will last 30,000+ hours
No consumables and minimal maintenance
Fiber laser can be replaced in the field by customer with no laser alignment necessary
Beam quality is higher than Flash Lamp, Diode pumped and Vanadate.
High beam quality allows the 10W and 20W laser to match the performance of a 85W laser for most applications
Air-cooled design
Better Cost of Ownership than Flash Lamp, Diode Pumped and Vanadate system
110V 1-phase, 15A Q-Switching range from 20 kHz to 80 kHz
Smallest footprint of any laser technology. Easy to integrate on existing assembly lines.
Can be mounted in any orientation.

Disadvantages of Fiber System:

Q-switching can only go as low as 20kHz. Applications requiring low q-switch frequencies such as deep engraving and some medical plastics will need to use either a flash lamp or diode pumped laser.
Small spot size may increase mark time
Diodes can be repaired but laser needs to be sent to factory.
Estimated cost to repair $2k to $4k

CO2 Laser

CO2 laser is a gas laser that is used to mark on “organic” materials such as wood, glass, packaging and plastics. It delivers a non-contrast mark on most materials.

Benefits of a CO2 Laser system:

Available in 10, 30, 60 and 100 Watt models
Lowest initial costs of all lasers. ~$20k to $25k for 10W system
CO2 tube will last 45,000+ hours
No consumables and minimal maintenance
Air-cooled design
Cost to recharge tube is $2k
Best Cost of Ownership over Flash Lamp, Diode Pumped, Vanadate and Fiber systems
110V 1-phase, 10A
Small footprint for ease to integrate on existing assembly lines.
Can be mounted in any orientation.

Disadvantages of a CO2 system :

Not a q-switched laser. The beam is pulsed but does not deliver peak power.
Limited applications. Can remove anodize and paint but can not etch or engrave into metals.
Recharge of tube requires laser to be sent back to factory. Alignment of system may need to be performed.
Larger spot size than YAG lasers. It has 10x the wavelength of YAG lasers at 10.6 microns. Bigger spot will reduce power density and resolution.
YAG (4.5” field) 25-35 microns
CO2 (4.5” field) 300 microns

Flash Lamp Laser

Benefits of a Flash Lamp Laser system:

Technology has been developed for over 20 years
Field proven design for industrial environments, a true
work horse
Most versatile and flexible system with variable beam
expander, spatial apertures and f-theta lens options. Ideal for job shop environments.
Flash Lamp will run for 500 to 1000 hours. Easy to install.
Flash Lamp costs $150.
Laser Power ranges from 50 to 150 Watts
85W system will cost the same as a 20W diode pumped system
Modular design allows for on-site repair
Q-Switching range from 1 kHz to 60 kHz

Disadvantages of Flash Lamp System:

Large foot print
Must be mounted in the horizontal position
Flash Lamp is a consumable
Highest Cost of Ownership 208 3-phase, 20A
Water cooled (Distilled water reservoir)
Chiller required

Diode Pump Laser

The diode pumped laser is very similar to the layout of the flash lamp laser. (Refer to previous diagram) Instead of a flash lamp to activate the rod, a cluster of light emitting diodes are used.

Benefits of a Diode Pumped Laser system:

Diode Pack requires no consumables and minimal maintenance
Diode pack lasts between 5,000 to 10,000 hours
Versatile and flexible system with variable beam expander, spatial apertures and f-theta lens options.
Laser Power ranges from 20 to 100 Watts
High beam quality allows the 20W laser to match the performance of a 85W laser for most applications
Water cooled, but has built in chiller. (Flash lamps require external chiller)
Better Cost of Ownership than Flash Lamp system
208 1-phase, 15A
Water cooled (Distilled water reservoir)
Modular design allows for on-site repair
Q-Switching range from 1 kHz to 60 kHz
Smaller footprint than Flash Lamp (38” length versus 54” length)

Disadvantages of Diode Pumped System:

Larger foot print as compared to Fiber
Must be mounted in the horizontal position
Diode Pack replacement costs between $7k and $10k
Diode pack can be replaced in field but may require laser alignment
Higher Cost of Ownership versus Fiber
Must be in a controlled environment. Diodes are cooled and held to a constant temperature of 70 degrees Fahrenheit. Ambient temperature higher than 70 degrees will create condensation, which can cause damage to the diode pack.

Vanadate

Very similar to Nd:Yag Diode Pumped

Different crystal for rod: Nd:YVO4
Designed to deliver more peak power at higher q-switch frequencies.

Benefits of a Vanadate system:

Higher peak energy allows you to move spot faster but still maintain dot overlapping for continuous line.
Smaller package than flash lamp and diode pumped
Fiber delivered head allows ease of integration
Air Cooled
Diode Packs last between 15,000 to 20,000 hours
No consumables
Better cost of ownership than flash lamp and diode pumped
Can be mounted in any orientation
Q-switch frequencies from 20 kHz to 200 kHz
Runs on 110VAC

Disadvantages of a Diode Pumped system:

Diode pack replacement costs between $5k to $7k
No repairable parts in laser head. Must send system back to manufacturer for repair
Fixed beam size. No adjustment for beam expansion or focus.
Q-switching can only go as low as 20kHz. Applications requiring low q switch frequencies such as deep engraving and some medical plastics will need to use either a flash lamp or diode pumped laser.
Small spot size may increase mark time

Laser Marking Software

What You See Is What You Get (WYSIWYG) Interface
Windows based
Easy to use, intuitive interface
Can easily create text and barcodes
Text: True Type and Stroke Fonts
Barcodes: Code 128, Code 3 of 9, 2D data matrix Serialize, Date Codes, Time Stamps
Import graphics directly into software
DXF, WMF, EPS, BMP, JPEG’s
Control and apply Laser Parameters
Interface to external equipment such as PLC’s, XYZ actuators, Rotary Indexers

Why Use a Laser Mark?

Permanent mark on variety of materials
Non-contact to part
Repeatable every time
Software allows user to easily add,
change and delete text, graphics,
barcodes, etc
Minimal consumables as compared to
ink jet and pad printing
Cost effective