Application example
Glue bead on electronic housings
- Challenge
- Transparent glue had almost no 2D contrast.
- Setup
- Laser line profiler with encoder sync, 3D height and width tools.
- Result
- Bead height, width and gaps measured along the full path.
Components · 3D
3D Vision
3D vision measures height, shape and volume — information a 2D image cannot provide. It finds defects with depth but little contrast, measures geometry directly in millimetres and tells robots exactly where parts are.
Thị giác 3D đo chiều cao, hình dạng và thể tích — thông tin mà ảnh 2D không có. Phù hợp cho lỗi có độ sâu, đo hình học và dẫn hướng robot.
How it works
Laser triangulation — measuring height from an angle
A laser projects a line onto the part. The camera views the line from an angle; where the surface is higher, the line appears shifted on the sensor. From this shift and the known geometry, the sensor calculates a height profile across the line.
As the part moves under the sensor, profiles are stacked into a complete 3D height map. An encoder keeps the spacing between profiles constant regardless of speed changes.
Other technologies work differently: structured light projects patterns over an area and captures a whole 3D image of a stationary scene; stereo compares two views like human eyes; time-of-flight measures how long light takes to return.
Types
3D technologies in detail
Open each type for how it works, where it fits, its limitations and the specifications to check.
01 3D laser line profilerHigh-precision height profiles of moving parts.
How it works. Laser triangulation with an integrated camera and processing. Delivers thousands of points per profile at high profile rates; parts move under the sensor to build a 3D image.
Best for
- Glue bead height, width and continuity
- Weld seam and solder inspection
- Coplanarity, steps and gaps
- Embossed text on tires and castings
Limitations
- Requires relative motion
- Occlusion behind tall features (use two sensors)
- Shiny surfaces can create false reflections
Key specs to check
- Points per profile / X resolution
- Z repeatability
- Profile rate (Hz)
- Measuring range
- Laser color and class
02 Structured-light 3D cameraFull-area 3D snapshots of stationary scenes.
How it works. A projector casts a sequence of patterns; the camera measures how they deform to compute a dense point cloud of the whole field of view.
Best for
- Bin picking and robot guidance
- Flatness and warpage of panels
- Assembly verification in 3D
Limitations
- Scene must be still during the pattern sequence
- Sensitive to strong ambient light
Key specs to check
- Field of view and working distance
- Point spacing
- Z accuracy
- Capture time
03 Stereo 3D cameraTwo cameras compute depth like human eyes.
How it works. Matching features between two views gives depth. Active stereo adds a projected texture so plain surfaces can also be measured.
Best for
- Larger volumes and robot cells
- Depalletizing and logistics
- Outdoor or ambient-light scenes (active/passive)
Limitations
- Lower precision than profilers
- Needs surface texture or projected pattern
Key specs to check
- Baseline
- Depth range
- Depth resolution
- Frame rate
04 Time-of-flight (ToF) cameraDepth from the travel time of light.
How it works. Each pixel measures the time (or phase) for emitted light to return, producing a depth image at video rates.
Best for
- Box dimensioning and volume
- People and object detection
- Fill-level of bins
Limitations
- Millimetre-to-centimetre accuracy, not micrometre
- Multipath errors in corners
Key specs to check
- Depth range
- Accuracy
- Resolution
- Frame rate
05 Confocal and interferometric sensorsVery high precision on transparent and mirror surfaces.
How it works. Chromatic confocal sensors focus different wavelengths at different heights; the returning wavelength reveals distance — even through glass layers.
Best for
- Glass thickness and layer distances
- Mirror-like and transparent parts
- Micrometre-level height measurement
Limitations
- Small measuring range
- Point or line, not full-area
Key specs to check
- Measuring range
- Resolution
- Spot size
- Sampling rate
Compare
3D technologies compared
| Technology | Typical precision | Motion | Best for |
|---|---|---|---|
| Laser line profiler | Micrometres to tens of µm | Part must move (or sensor) | Inline inspection of height and shape |
| Structured light | Tens of µm to sub-mm | Scene stationary | Area 3D, bin picking, flatness |
| Stereo (active/passive) | Sub-mm to mm | Works on moving scenes | Robot cells, logistics, large volumes |
| Time-of-flight | mm to cm | Video rate | Dimensioning, presence, volume |
| Confocal | Sub-micrometre | Point/line scanning | Transparent and mirror surfaces |
Precision depends strongly on field of view, working distance and surface; values indicate typical ranges only.
Specifications
Key 3D specifications explained
| Specification | What it means | How to choose |
|---|---|---|
| X resolution | Spacing of points along the laser line (FOV ÷ points per profile). | Must resolve the smallest feature across the line. |
| Y resolution | Spacing between profiles in the motion direction. | Set by speed ÷ profile rate (see calculator). |
| Z repeatability | Variation of repeated height measurements. | Should be about 1/10 of your height tolerance. |
| Measuring range (Z) | Height range the sensor can measure. | Must cover part height variation and mounting tolerance. |
| Profile rate | Profiles per second (Hz). | Higher for faster motion or finer Y spacing; ROI can increase it. |
| Laser color | Red or blue (violet) lasers. | Blue lasers often perform better on shiny metals and hot glowing parts. |
| Laser class | Safety class of the laser. | Plan guarding and labelling according to class. |
| Interface & sync | Ethernet, encoder input, triggers. | Encoder sync keeps constant spacing at varying speeds. |
Engineering tools
Calculate before you choose
Quick estimates based on standard formulas. Always confirm with a test on real parts.
3D Profile Rate Calculator
From conveyor speed and the desired spacing between profiles, calculate the required profile rate and the X resolution of the scan.
Selection guide
Which 3D technology for which task?
| Requirement | Recommended | Why / note |
|---|---|---|
| Glue bead height, width, gaps | Laser line profiler | Inline, high precision. |
| Pin and BGA coplanarity | High-resolution profiler or structured light | Micrometre-level Z repeatability. |
| Bin picking of random parts | Structured-light or active stereo camera | Area 3D for robot guidance. |
| Box dimensions and volume | ToF or stereo camera | Fast, larger volumes. |
| Embossed text on tires or castings | Laser line profiler | Reads height, not color. |
| Flatness of large panels | Structured light or multiple profilers | Full-area coverage. |
| Glass thickness, transparent layers | Confocal sensor | Measures through transparent layers. |
Selection steps
- Define what must be measured: height, width, volume, flatness or position.
- Set tolerances and required X, Y and Z resolution.
- Choose the technology based on motion, precision and field of view.
- Check occlusion and surface behavior (shiny, dark, transparent).
- Plan motion and synchronization (encoder, trigger, robot).
- Plan calibration and coordinate systems (especially for robots).
- Test on real parts across the full variation range.
Examples
Typical application examples
Illustrative setups showing how the components are combined in practice.
Application example
Battery cell surface and weld seam
- Challenge
- Shallow dents and weld irregularities on shiny metal.
- Setup
- Blue-laser profiler with exposure tuned for reflective surfaces.
- Result
- Depth-based defect detection independent of surface color.
Application example
Robot bin picking
- Challenge
- Randomly oriented metal parts in deep bins.
- Setup
- Structured-light 3D camera with 3D matching and robot calibration.
- Result
- Robot receives pick positions and orientations for each part.
Common mistakes to avoid
- Ignoring occlusion — tall features hide areas from the laser or camera.
- Triggering by time instead of encoder, causing uneven spacing at varying speeds.
- Underestimating reflections on shiny parts; angle, laser color and exposure matter.
- Skipping proper calibration between sensor, conveyor and robot.
- Choosing 3D when 2D with the right lighting would solve the task more simply.
FAQ
Frequently asked questions
When do I need 3D instead of 2D?
When the information is in height or shape (dents, bead height, coplanarity, volume) or when parts are not in a fixed position for a robot. If good lighting creates clear 2D contrast, 2D is usually simpler and faster.
Why use two profilers?
To avoid occlusion: each sensor sees areas hidden from the other, and the data is merged into one height map.
Are lasers safe?
Industrial profilers use defined laser classes. Lower classes need little protection; higher classes require guarding and labelling. We design the station to match the class.
Red or blue laser?
Blue lasers often perform better on shiny metals, organic materials and hot glowing objects; red lasers suit many general surfaces.
Can 3D sensors measure moving parts?
Laser profilers need motion to scan. Stereo and ToF capture moving scenes at video rate; structured light usually needs the scene to be stationary.
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