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Laser materials processing

1 Introduction 2 Laser beam Generation

1 Introduction 2 Laser beam Generation

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This flashcard set covers university-level concepts in laser materials processing, focusing on the principles of laser operation, types of lasers, and their applications. It delves into the advantages and disadvantages of different laser types like diode, YAG, and CO2 lasers, and explores their use in welding, cutting, and hardening materials. The flashcards also explain key characteristics of laser beams, such as coherence and monochromaticity, and discuss the dangers associated with infrared laser light. This set is ideal for engineering students or professionals seeking to understand the technical aspects and practical applications of laser technology in material processing.
Flashcards
9
Students
2
Language
English
Category
Technology
Level
University
Created / Updated
07.01.2015 / 07.01.2015
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Flashcards

How is a laser beam defined?

Name the 3 main characteristics.

1. monochromatic (always a precondition for coherence)

2. coherent

3. almost perfectly parallel

In wich "region" can most of the lasers for materials processing be found? Name 3 of those laseres.

What specific dangour results from this characteristic?

The most common lasers for materials processung can be foun in the infrared region. (CO2 - / YAG- / Diode-lasers)

The dangour of infrared (laser) light is the invisibility.  

Examples for Laser Materials Processing:

Where can using a laser beam for materials processing be meaningful?

  • welding on heat-sensitive parts
  • welding or hard-brazing of welds in the "viewing-range" of a product
  • transmission laser welding of plastic parts
  • laser cutting (eg. Stants)
  • laser drilling (for very small diameters)
  • laser hardening

How to achieve light emission with only 1 wavelength (=monochromasie)?

Using only one single kind of atoms or molecules and exiting them in one defined way. Some materials then start to emit light in only one defined wavelength.

Suitable materials for the construction of a Laser are those materials, that – when they are pumped with excitation energy – start to emit energy dominantly in form of light (and only in minor amount as heat). These useful materials to construct a laser are called „Gain Media“ or „Laseractive Media“ or „LAM“.

How to achieve coherence and emission into 1 direction?

Place two mirrors around the LAM. Thus, the part of the light-waves which is at random emitted in the axis-direction between the two mirrors don´t leave the LAM. Instead they run through the LAM several times in the 1 unique direction given by the axis between the mirrors.

stimulated emission "LASER-effect"

Laser Amplification by Stimulated Emission of Radiation

Name the main advantages and disadvantages of CO2-Lasers.

CO2-Lasers:

Main specific advantage of CO2-lasers: 

Low investment costs per kw laser-power.

Main specific disadvantage of CO2-lasers:

Beam not transportable via fiber-cable. (wavelength is too long for glass-transmission)

 

Name the main advantages and disadvantages of YAG-Lasers

YAG-Lasers:

Main specific advantage of YAG-lasers:

Many, such as good absorbtion in metals, fiber-cable ability.

Main specific disadvantage of Diode-lasers:

None.

Name the main advantages and disadvantages of Diode-Lasers.

Diode-Lasers:

Main specific advantage of Diode-lasers:

Very compact, best efficiency.

Main specific disadvantage of Diode-lasers:

Lower focusability (poorer beam quality).

Wich are the typical operation modes for operating a processing lasel?

  1. continous wave mode
  2. pulsed mode
  3. giant-pulse mode (Q-switch mode)

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