When scanning your products, we will select the right technology that delivers the accuracy, speed and resolution you need for your application. We also consider the size, color and reflectivity of the object.
The technologies that we use include laser scanners, white light scanners and CT scanners. The laser scanners are mounted on a ROMER arm or tracked with an NDI optical system. This allows us to capture scan measurements in an area up to 18 feet in diameter and at a rate of nearly 500,000 points per second. The white light scanners, which are mounted on a tripod, capture more than 1,000,000 points per second. In a single shot, the white light scanners take measurements in an area ranging from a few square inches to a few square feet. CT scanners allow for the easy measurement of the internal structures of parts by generating a point cloud from a number of two dimensional x-ray pictures.
When it comes to a discussion about “White Light vs. Laser Scanning”, those unfamiliar with the technologies may believe that we’re about to proceed into an article rating all of the Sci-Fi flicks from the last century. But we save those debates for lunch break. One of the most frequently asked questions the Exact Metrology team gets is: “What is the difference between white light and laser scanning?” And since our customers are often unsure of which would best suit their project, we decided to devote some space in this newsletter discussing the two.
Both 3D white light and 3D laser scanners are used for inspection and reverse engineering purposes. Both are close range scanners that will record data quickly and to a sub-millimeter level of accuracy. But each type of scanner has unique properties that make them more or less fitting for certain applications.
To illustrate the difference between white light and laser scanners, we grabbed your everyday deodorant bottle off the shelf and scanned some of its components using each type of scanner. The differences are illustrated below:
3D white light scanners are usually tripod mounted. Scan data is obtained shot by shot, as a grid of light is projected and laid over the component being scanned. As a scan is completed the grid is modified, and the scanner determines the 3D coordinates by calculating the returned patterns.
3D laser scanners are usually handheld or tripod mounted, and scan data is obtained as a laser stripe sweeps over a component or entire area. The handheld type is typically attached to an arm, which provide a constant readout of where the scanner is at any time.
When it comes to white light and laser scanners, there are several important differences one should take into consideration when planning their project. These include:
One significant difference in white light scanner and laser scanner results is in point density. To illustrate this example, let’s use the screw and crank from a deodorant bottle.
You can see from this side-by-side comparison the difference in detail the scanners are able to obtain. This detail is obtained not by accuracy but by having points closer together.
If the goal of the scan were to capture data about the general size and dimensions without the intricate details of the screw and dial, the ROMER Arm and laser scanner will capture this general shape. If the goal of the scan is to reconstruct the dial exactly, the white light scanner has point spacing that is much closer and will record the dial with greater detail.
When it comes to speed and efficiency of a scanner, laser scanners have the advantage of speed, due to the fact that they can do one sweep much more quickly than the multiple shots a white light scanner obtains. For example, the ROMER Absolute RS2 can scan 50,000 points wirelessly, with real-time exposure.
But with the next-generation cameras, electronics and processors now used, white light scanners can now obtain scan data containing over 8,000,000 points in an area as small as 30mm square and in as little as a few seconds. Due to this rapid scanning speed, white light scanners have been found to be incredibly useful in face scanning and body scanning applications, since people often find it difficult to stand still. However when many shots are required to cover the part in points additional time is required.
White light technology is capable of accuracies up to less than 0.001 of an inch in small volumes. Once the volume gets over roughly one foot cubed, the accuracies will match that of the laser scanner at roughly 0.003 of an inch.
Since each job is truly unique, your Exact Metrology rep will advise you on which type of scanning will achieve the greatest accuracy based on your project’s volume.
A white light scanner is typically more expensive than a laser scanner. While low-cost white light scanners are available, the data they obtain is typically not up to par with that obtained by the higher quality scanners. Therefore, if scan data provided by a laser scanner will meet the needs of a project, this is often the choice our clients go with. If scan data with greater detail is needed, then white light would be a better choice. You can talk with your Exact Metrology representative for a recommendation guaranteed to fit your requirements.
Each of these technologies offers high resolutions of approximately 0.0005 inch. Combined with accuracies that rival conventional CMMs, our laser and white light scanning technologies are perfect for tiny objects and large manufactured parts.
Should you have any additional questions about 3D white light or 3D laser scanning, please feel free to Contact Us for more information or for a quote. We are happy to provide any assistance we can on choosing the right device for your project, and thank you for considering Exact Metrology for your inspection and reverse engineering needs.