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Views: 0 Author: Site Editor Publish Time: 2026-06-15 Origin: Site
Laser systems are widely applied in cutting-edge fields including material processing, laser surgery and remote sensing. Regardless of diverse application scenarios, several core physical parameters usually determine the performance of the entire system.
Miscommunication, improper component selection and even system damage in projects often stem from misunderstandings of these basic terms.
Based on the Laser Optics Resource Guide, we have sorted out 12 key parameters of laser systems. Establishing a unified terminology system can not only avoid expression errors, but also help you select solutions that precisely match application requirements.
A solid grasp of fundamental concepts for laser characteristics is the prerequisite for learning advanced knowledge.
Wavelength dictates how laser light interacts with materials.
· Material Processing: Different materials show vastly different absorption rates for laser beams of varying wavelengths.
· Precision Control: Short-wavelength lasers (e.g., UV lasers) deliver smaller focused spots with an extremely narrow heat-affected zone, ideal for ultra-precision machining. However, they come with higher costs and are more vulnerable to damage.
· Environmental Adaptation: For remote sensing and medical applications, atmospheric interference and absorption characteristics of skin tissues also need to be taken into account.
These parameters indicate the output intensity of a laser.
· Continuous Wave (CW) Lasers: Rated by optical output power (Watts, W).
· Pulsed Lasers: Evaluated by average power and pulse energy (Joules, J).
Key Note: Pulse energy is directly proportional to average power and inversely proportional to repetition rate.
Figure 1: Visual illustration of the relationship between pulse energy, repetition rate and average power of pulsed lasers
Also known as pulse width. It is generally defined as the time duration at Full Width at Half Maximum (FWHM) of the laser's peak optical power.
· Ultrafast Lasers: Pulse duration reaches the picosecond (10−12 s) or even attosecond (10−18 s) range, delivering exceptional machining precision.
Figure 2: The pulse interval of a pulsed laser is the reciprocal of its repetition rate
It refers to the number of pulses emitted per second.
· Thermal Effect: A higher repetition rate leads to faster heating of materials due to shorter thermal relaxation time.
· Trade-off: With constant average power, a higher repetition rate generally means lower single-pulse energy.
Coherence is a key feature that distinguishes lasers from conventional light sources. Coherence length is the propagation distance over which the laser maintains stable phase correlation. It is critical for applications such as holography.
It indicates the direction of the electric field. Most lasers produce linearly polarized light. A higher polarization ratio (e.g. 100:1) means better polarization purity, which is essential for systems equipped with polarization-sensitive optical components such as isolators and waveplates.
The shape and quality of a laser beam directly determine its propagation and focusing performance.
Typically defined at the 1/e² width (where the light intensity drops to 13.5% of the peak value).
· System Cost: A larger beam requires bigger optical components, which increases costs.
· Key Trade-off: Reducing beam diameter cuts costs but greatly raises power density, risking component damage.
It represents energy per unit area.
· Inside the System: Lower density is preferred to avoid optical component burnout and air ionization. Beam expanders are commonly used to enlarge beam diameter for this purpose.
· At Output End: High density is required for cutting and welding to guarantee processing efficiency.
The intensity distribution across the beam cross-section.
· Gaussian Beam: Energy concentrates at the center with a high peak intensity.
· Top-hat Beam: Features uniform energy distribution, ideal for surface treatment.
· Practical Note: Perfect ideal beams do not exist. The M² factor is used to quantify the deviation between an actual beam and an ideal Gaussian beam.
Figure 3: Comparison of beam profiles between Gaussian beam and top-hat beam with identical average power/intensity. The peak intensity of the Gaussian beam is twice that of the top-hat beam.
A laser beam is never perfectly parallel and will always diverge.
· Long-range Applications: Divergence serves as a core indicator for LiDAR and similar systems.
· Control Method: Increasing the beam waist diameter effectively reduces divergence — another key application of beam expanders.
These parameters describe the state of the laser beam reaching the target after passing through the optical system.
It refers to the beam diameter at the focal point of the focusing lens.
· Application Requirements: Ultra-small spots are required for micromachining and laser surgery, to achieve high power density and precise processing results.
· Optimization Tip: Replacing spherical lenses with aspherical lenses minimizes spherical aberration and delivers a smaller focal spot.
Figure 4: Laser micromachining experiments conducted by the Istituto Italiano di Tecnologia show that at constant fluence, reducing the spot size from 220 µm to 9 µm boosts the ablation efficiency of the nanosecond laser drilling system by ten times ¹.
It is the physical distance from the last optical component to the focal point.
· Medical Applications: Usually short.
· Remote Sensing & LiDAR: Covers an extremely wide range.
These 12 parameters form the framework of a laser system, covering laser generation (wavelength, pulse characteristics), beam propagation (diameter, divergence) and final focusing (spot size, working distance).
Whether designing a new optical system or purchasing off-the-shelf laser components, accurate definition of these parameters is the first step to avoid costly errors.
Figure 5: Schematic diagram of a typical laser material processing system, with 10 key parameters of the laser system marked by corresponding numbers.