Laser Profile Vs Snap-Shot in 3D Control Applications
One of the first questions that comes to mind when planning a 3D vision inspection application is which type of 3D sensing technology will be used. When we look back at the answers, we will encounter two options: Structured light profile devices and line laser profile devices. Application requirements will determine which of the two profile device types to choose.
Line Laser Profile Devices
The working logic of line laser profilers and line scan cameras is similar. In order to reveal a 3D structure, the object to be controlled must move under the laser light beam emitted in a line. As a result of this movement, the correct position of each point on the object is determined and a 3D model is obtained by combining them.
An Alternative to Laser Scanning: Snapshot Sensors
Snapshot profile devices take a snapshot of a fixed part under structured light and can present it directly to you as a 3D model. This will save you from the trouble of installing a costly mechanical system, and the presence of vibrations that significantly affect the repeatability of measurement will no longer be a problem.
Round 1: Movement
Snapshot devices are the most suitable solution in applications where the product is fixed during the control phase.
Like the snapshot sensors we just mentioned, 3D object geometry emerges with a cloud of points determined based on the light pattern reflected on the product surface. If the object moves while collecting the placed points and extracting the 3D object geometry, errors may occur in the results.
When the product is in motion, on any conveyor or transfer line, line laser profile devices are the optimal solution.
Line laser profile devices collect a set of profile information from the laser projected onto the object as the object passes in front of the image sensor. Firmware 3D smart sensors can be used to collect profile arrays and create a complete 3D geometry of the object surface. One thing to consider is that if the object transfer rate is constant, time-based sampling can be done. However, in cases where the movement speed may change, errors resulting from variable movement should be prevented in line with the information received from an encoder while creating the 3D geometry of the product.
Round 2: Security
Snapshot devices generally use LED light, which has no security issues.
Line laser profile devices, on the other hand, use a laser light source that has the potential to cause eye damage (depending on the laser type). It can reach high scanning speeds with its high laser power, being unaffected by ambient light and working at low exposure times. However, high laser power has the potential to bring about reliability losses.
Round 3: Installation
Using snapshot sensors in a specific application is in some ways a simple process. While the product is stationary, exposure, filtering and analysis settings are optimized with the 3D point cloud obtained from a single shot image. This means that the user does not need to deal with these settings.
On the contrary, line laser sensors have a 3D image creation procedure. The product must move in a controlled manner.
