Laser Intensity
The laser is the heat source that decides bonding. How its power is shaped, aimed and spread over the tape and substrate matters as much as how much power there is.
Thank you for reading this post, don't forget to subscribe!A laser beam is a bundle of rays, each carrying a share of the energy, travelling in parallel or diverging paths. Where those rays land, at what angle, and how much of their energy is absorbed sets the heat input, and with it the temperature at the nip point.
Same power, different heat
- Total power sets how much energy is available
- The intensity profile sets where it is delivered
- Geometry and incidence angle set how much is absorbed
- Divergence and distance set the spot size on the part
Uniform or Gaussian?
Diode lasers can produce different intensity profiles. The two most common are uniform (top-hat) and Gaussian.
- Even heating across the spot
- Predictable on flat and gently curved parts
- Sharp edges can over-heat tape edges or the roller
- Peak intensity at the centre
- A soft fall-off reduces edge effects
- Risk of local over-heating at the peak
What influences the delivered intensity
Tooling geometry
Curvature changes the incidence angle along the path. On a vessel dome the peak intensity can rise by about 80%.
Laser distance and angle
Stand-off and tilt or yaw of the head move and stretch the spot between tape and substrate.
Divergence and spot size
A diverging beam grows with distance and spreads its energy over a larger area.
Shadowing
The roller, the incoming tape and the part geometry can block rays before they reach the nip.
Reflection
Fibre-orientation-dependent reflection sends energy to neighbouring surfaces.
Multiple modules
Several laser modules or zones can be combined and balanced across the tape width.
How OTOM handles laser intensity
Model the source
Uniform, Gaussian or custom distributions, with divergence, spot size and multiple laser modules, placed by the head kinematics.
Trace the rays on the GPU
Every ray is traced against tool, tape and roller with Fresnel absorption and reflections, giving the absorbed power on each surface.
Vary power over the path
Power can change step by step along a course, from a table or from an optimised schedule.
Optimise
Laser power and source position are adjusted per station to hold the target temperature. In AFP Web this takes about 10 seconds.
Choose the right profile for your set-up
We analyse your laser, head and tooling and recommend the intensity profile and power schedule that give uniform bonding.