Gravograph Laser Engravers

Gravograph Laser Engraving
LS100 Laser Engraver
LS700 Laser Engraver
LS800 Laser Engraver
LS900 Laser Engraver

Laser Engraving Terminology from Gravograph-NewHermes

Gravograph provides you with this convenient list of commonly-used laser engraving terminology. The definitions we have provided include both general terms as well as those specific to our equipment or terminology that we frequently use.

Laser Source (resonator, laser tube) – This component includes the RF power supply that drives the laser.

CO2 (Carbon Dioxide) – This is the type of laser source that Gravograph uses in our laser engraving units.

Wavelength – The physical distance cover by one cycle of the wave. In the case of CO2 lasers it is 10 micrometer (µm).

Frequency – The number of times a wave peaks in a given time. This is expressed in either hertz or cycles per second.

Focal Lens – This is a mounted optic through which the laser beam is fired. Its purpose is to control the incoming light and focus it to a useful size in the laser engraving machine.

Focal Point – The point on the optical axis of a lens, where all of the parallel light components converge to construct the tightest focused "spot" possible.

Collimation – The optical process of aligning to effect divergence and focal length within the optical train of the laser. This makes every molecule, more or less, parallel with the others in a given beam.

Divergence – Is the natural angle, unfocused light will adjust to, if not artificially adjusted via optics or apertures.

Beam Expander – An optics that multiplies the size of the collimated beam, before introduction to focusing optics.

Depth of Focus – The natural condition that develops when using a focusing axis that provides a tolerance for focus. Each focal length lens has a specified depth of focus.

Excitation – The process, in which the active components in the laser cavity is stimulated to produce the energy to initiate the lasing process.

Plasma – The "plume" that is generated from processing many materials. This is a gas that contains electrons and ions. This differs from the flame that is generated when processing some materials like wood or acrylic.

Average Power – Combination of the energy per pulse and the frequency, expressed in watts. This is the measurable power at the work piece on the laser engraving machine.

Power Density (Peak Power) – This is the max power, per pulse at the work piece. This is harder to measure and is typical is a factor in higher power lasers, however it does create the highest factor when measuring average power.

Optical Density – The measure of transmittance through an optical medium. Reference would be the filter glass on the laser cover and the special goggles used when working around lasers. This will be referred to as O.D.

M2 Value – This is the quality measurement for the laser source. The lower the number the better overall quality the beam has. The Gravograph laser engraving machines have an M2 value of about 1.2, which is excellent.

Overall Distance (Overall Length) – This is the physical distance from the beginning of the laser output to the work pieces. The overall distance is key in adjusting the optics to compensate for natural divergence. To put it in perspective, on an LS800 with A 2" lens, the overall distance is calculated approximately as follows:

End of the Laser Source to the Fold Mirror (In the Optical Block) = 2.0"

Fold Mirrors to the 45 degree, moving mirror on the gantry = 10.0"

45 degree moving mirror to the 45 degree down fold mirror = 24.0"

45 degree down fold mirror to the first surface of the focal lens = 2.0"

Focal lens (focal length) to the work piece = 2.0"

X-Axis Travel = 12.0"

Vector vs. Raster Mode

The two true processing modes we run the laser in are Vector and Raster. Both have unique advantages and disadvantages.

Raster Engraving – Is the most common processing and is used for photographs, bitmaps, true type fonts and large filled areas. This consists of the gantry head "scanning" left to right and top to bottom to deliver the beam. In a gantry configuration, linear speed is greater as the processing is done, all with straight lines.

Vector Engraving – Vector processing actually steers the beam much like you might write with a pen. It is the best process when lasing single line fonts, outlined images, very small open contours and when you are cutting. As the vector mode requires a transverse curve on almost a constant basis, the speed is much less at 7.9"/sec maximum.

Contact Us

If you would like to learn more about laser engraving, or if you have questions about any of the above terms, please contact us. We look forward to hearing from you.