Laser projection systems for outlines and templates based on CAD data

The geometry of the setup, the complexity of the projected shapes, the ambient conditions and the material of the projection surface can all affect the visibility of the projected laser image.
We have provided some useful information below to help you decide how to best use laser projectors for your application.

Our experienced sales team will also be happy to assist you in finding the optimal solution for you.

To get a bright line, the laser needs to be more powerful than the ambient light.

Rule of thumb: The brighter the surroundings, the more laser power you need.

• In dim light, little laser power is necessary (5 mW).
• Artificial light requires medium power (10 mW).
• Maximum power is needed for use in bright artificial light or daylight (30 mW).
• Depending on the situation, direct bright sunlight on the projection surface may outshine the laser projection.

The visibility of a laser depends on the light absorbed or reflected by the surface you are projecting onto.

Rule of thumb: The more light is absorbed, the more laser power is required.

• Transparent or translucent materials, for example glass, don’t reflect much light. It can be very difficult to see laser lines projected onto these materials, if they are visible at all.
• Matt black surfaces absorb a lot of light and reflect little. Here you need a lot of laser power to get a visible outline.
• Shiny surfaces reflect laser beams by the rule “angle of incidence equals angle of reflection”. If you look at the surface at a different angle, you may not see any projected lines.
• Wet, dusty or greasy surfaces have varying reflectivities. Results can only be determined by tests.
• Rougher surfaces such as brushed or milled grooves can swallow parts of a line and only show a shape with reduced brightness or the brightness depends on the viewing angle.

Give our sales team a description and they will be happy to assist you.

Rule of thumb: Green lasers tend to have better visibility than other colors.

• In general, the human eye is more sensitive to green light than to red light.
• Still, the surface color and structure of your object may be better suited for red lasers (see “material and surface”).
• Different laser projection colors offer new options for your workflow.

Our sales team will be happy to help you find the option that suits you best.

The maximum projection area is virtually unlimited, as projectors can be networked together to project onto larger tools or objects. Floor plans in exhibition halls can have projection areas of several thousand square meters. Molds for rotor blades of wind turbines with a length of 100 or more meters can be covered.

The maximum projection angle is 80°×80° below the laser exit. You can visualize the model as a square based pyramid with the laser projector at its top. Minimum projection height is 1.5 m. Maximum distance to a calibration target is 15 m, which limits the perpendicular height about a flat surface to 11.5 m.

For projectors mounted at a height H perpendicular above a flat surface you find:
Formula for the length of the sides s of the maximum projected square:
s= 2×H×tan 40° (rounded H×1.7)
Formula for the projection area a depending on the mounting height:
a= s²  (rounded H²×2.9)
 

The projected laser lines are generated by a laser spot that moves along the required coordinates in an optimized order. If this happens fast enough (> 24 times/second) it looks like a stable image. Depending on the ambient illumination, the lines start to flicker if the frequency is reduced. This may happen if the outline to be projected is too complex. In this case, the projection data has to be simplified or the number of projected elements has to be distributed to several layers. Alternatively, several projectors may cover the same area and distribute the load between them.

There is no formula to calculate the maximum of projected lines before flickering starts, as it depends on many factors: the lines' shape, their position, their distribution over the projection area, the 3D shape of the surface and the potential for optimizing the way the laser spot has to move.

The basic manual calibration only needs to be done once for each new tool or mold you use. If you calibrate a fixed workspace like a table, you only need manual calibration once during first installation.

After that the calibration procedure can be done semi-automatically for movable tools or molds without DTEC-PRO camera/flash support. Fixed workspaces or setups including DTEC-PRO can always be calibrated completely automatically.

Fixed workspaces should be calibrated once a day or at the beginning of a shift, movable tools whenever there has been a planned or involuntary change of location.

A relocation of the complete workplace is easy. Just move the whole system, do a new basic calibration and start working.
If the once calibrated position of workplace or projector moves involuntarily or intentionally, the new positions have to be related by a re-calibration. Depending on situation and equipment, this may be done manually, semi-automated or completely automated by using the DTEC-PRO camera/flash system.
If the displacement is controlled, like movement on a guide rail or a defined rotation, you may use encoder signals to adjust the projection accordingly.
Setups with fixed projector and constantly moving objects or fixed workplaces with a projector that’s movable, e.g. on a rail, are possible but elaborate. Most of the times the solutions are too complex and/or expensive compared to a solution with a fixed projection area or several projectors.

LAP projection systems can handle .dxf, .igs, .iges, .apt, .ply, .prt, .tps, .apt, .hpgl, and .lpd (proprietary LAP format) files with 2D or 3D content. The extraction of the elements to be projected and the organization of work steps in the correct order has to be done previously by the customer. For manual layup of composites, the composite design must be done manually or using special software or plugins to define plies, layers, sequences or stacking. CATIA CPM, SIEMENS NX Fibersim and Autodesk TruComposites are some typical tools for that. In general, you may use every software on the market, that can export one of the named file formats, from Solidworks to Creo. If you use Rhino 3D software, you may download a plugin for export of .lpd format for free from “Food for Rhino”.

Each projected laser spot is calculated based on the provided CAD model of the projection area and surface, including additional material that is placed during the work process.
Example: a straight line between two points is displayed as a straight line on a flat (x, y) plane or surface. On a curved (x, y, z) surface the line describes a curve according to the surface. If you place a cutout of flexible material with a straight edge on the curved surface, the edge will exactly match the projected line.
For projection on flat 2D surfaces you may manually change the z-coordinate (perpendicular to surface) to compensate for height changes not included in the projection file, e.g. material of different thickness.
3D projection is completely based on the underlaying CAD model of the surface. As long as the real surface complies with the CAD data, the projection will be precise at any point.

Every projection is based on a calibration process using exactly measured reference points. If the real position of the reference points doesn’t comply with the CAD model, the whole projection will be faulty.

Depending on mode, you may project data in a fixed order or free. You may have a second person check if previous work steps have been done correctly or if parts are complete by going back to the related projection. It will be possible soon to take pictures of work steps using DTEC-PRO IR flash and camera.
The projection software, PRO-SOFT, can only process data you entered before. There is no deep learning algorithm included, no sensors and no AI to check what you are doing and if you’re doing it correctly.
LAP laser projection systems can be used in cooperation with some third party power tools with position sensors and with intelligent workspaces. Please ask our sales team for details.

Please note the laser warning signs and instructions! For technical details and exact calculations regarding the laser class please read the relevant information of the laser standards of your country and the information of the professional associations.

To give you an overview of the potential dangers of our laser projectors, please read the following explanations. They should not replace the existing warning messages or downplay or belittle any hazard!

LAP laser projectors use two safety functions that prevent the system from projecting with more power than specified in the laser class: The laser driver has a control routine that switches off the laser source when certain parameters are exceeded. The PRO-SOFT projection software prevents individual points from being projected at full power. The laser power for individual spots is reduced to a maximum of 1 mW in laser class 2 projection systems.

The following comparison is a rough analogy to explain the order of magnitudes between the performance of a laser projection system and other laser applications:

LAP projection lasers work with laser powers of 1 … 30 mW (Milliwatts) = 0.001 … 0.03 W
(30 mW = 30/1000 watt)

Lasers for surgical purposes consume powers of 10 … 100 W
(30 mW = 0.001 x 30 W, that's 1000 times weaker)

Industrial lasers for cutting or welding metal have powers of 200 ... 10,000 W = 10 kW
(30 mW = 0.00001 x 3 kW, that's 100,000 times weaker)

Military laser cannons consume more than 30 kW
(30 mW = 0.000001 x 30 kW, this is a million times weaker)

We have no reliable information about the laser power of lightsabers, but since in the movies they cut through massive metal bulkheads from spaceships in seconds, we estimate more than 3 MW (> 3,000 kW).