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Getting the most from a 4D InSpec.

This page includes answers to many frequently asked questions regarding the 4D InSpec and 4D InSpec XL. It also includes links to our how-to videos,  applications notes and articles that explain the 4DInSpec’s capabilities and helpful information about how to make better measurements.

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Frequently Asked Questions


What types of surfaces can I measure with a 4D InSpec?

The 4D InSpec can measure a wide range of metals, plastics, glass, or ceramics. For good results, the measurement surface cannot be mirror-smooth, but as long as the surface is slightly rough it can be accurately measured. For instance, ultra-finished parts can readily be measured. For certain ceramics or other translucent surfaces, you may need to switch the unit from single-frame mode to multi-frame mode for best results.

Can the 4D InSpec measure into corners or areas without line-of-sight access?

Yes. The 4D InSpec has a long standoff distance of almost 1.7 in (43 mm) and a large depth of focus (0.08 in or 2 mm) and thus can measure features even in corners. With an optional fold mirror attachment the 4D InSpec can function like a borescope, measuring features with no direct line of sight.

The 4D InSpec XL, has a larger field of view and a longer standoff distance. However, its larger field of view is not well-suited to using fold-mirrors, so no fold-mirror accessories are offered for 4D InSpec XL at this time.


How can I quantify the features I measure?

The 4D InSpec software automatically will identify bumps or pits that meet user-defined height and width thresholds and will report height, area, volume, slopes, %area covered by the defects and more. Additionally, a user can easily draw 2D cursors across a feature of interest to see even finer detail and measure widths and heights even within a defect.

See the Feature Analysis video  to learn how to measure multiple features across the field of view.

View our “Shape Removal Software Tools video to learn how these controls let you remove complex surface shape from the measurement so that you can accurately measure the features of interest.

Can the 4D InSpec measure surface roughness?

The 4D InSpec is designed to accurately measure surface features such as scratches, pits, nicks, or protrusions as well as geometries such as radius, but does not measure surface roughness.


Can I measure features on a curved surface?

The 4DInSpec excels at measuring curved, complex surfaces. Software features make it easy to remove the shape from the measurement data so that you can accurately gauge the depth of features.

See our video, “Blade Edge Measurement with the 4DInSpec” to see how easy it is to measure features on a strongly curved surface.

Our video “Analyzing 3D Defects in machined parts with reference masks”  shows how masks can help you correctly calculate feature depths even on highly curved surfaces.

My surface is highly reflective. Will the 4D InSpec work?

In short, yes. But highly reflective surfaces can require angling of the instrument to reduce the light reflected back into the system.

Read our Application Note, Measuring Highly Reflective Curved Surfaces with the 4D InSpec,” to see how the brightness adjustment accommodates a wide range of surface reflectivity.

The Application Note, Measuring Transparent, Flat or Shiny Surfaces with the 4D InSpec,” may also be of interest.

Our video “Setting the Brightness with the 4D InSpec”  shows how quickly the instrument can be adjusted to accommodate a range of part reflectivity.

Can I measure rubber or other black materials?

Yes, the 4D InSpec is capable of measuring rubber, carbon fiber, and other very dark materials due to its bright LED source and sensitive camera.

Our video “Setting the Brightness with the 4D InSpec”  shows how quickly the instrument can be adjusted to accommodate a range of part reflectivity.

Can I measure radius of curvature? Blend radius?

Yes, the 4D InSpec includes an analysis specifically for measuring radii of curvature. View our video, “4D InSpec – Radius of Curvature”  to learn how to measure the radius of curvature, blend radius, etc., for precision machined components.

How does the measurement of the 4D InSpec compare with fluorescent dye techniques?

Like fluorescent dye methods, the 4D InSpec can only detect defects or features on the exterior of a part. It does not measure sub-surface features. However, unlike fluorescent dye techniques, the 4D InSpec’s measurements are not dependent on the surface roughness, and in fact have been shown to detect and measure cracks and pits much better than fluorescent dye techniques on such surfaces as 3D printed parts with a good deal of structure.

How does this measurement compare to using replica casting?

The 4D InSpec can directly measure defects on complex surfaces, in tight corners, over large surfaces, and in blind locations. The method is far faster than replication and does away with the mess and expense of replica production.

Replication is sometimes necessary when measuring areas which are inaccessible—even to a handheld instrument such as the 4D InSpec. Fortunately, 4D InSpec is equally accurate measuring properly replicated features as it is with direct measurements. Read our Application Note, Measurements of Various Defects and Their Replicas Using the 4D InSpec,” to learn more about working with, and replacing, surface feature replicas.


What is the difference between the 4D InSpec and 4D InSpec XL?

Like the 4D InSpec, the 4D InSpec XL gives you micrometer-level resolution, portability, affordability and ease-of-use. The 4D InSpec XL, however, has a larger field of view and higher scan range. The features you measure can be up to 0.6″ x 0.6″ across.

What is the resolution of the 4D InSpec?

The 4D InSpec can accurately and repeatably measure surface features from 0.1 mils (2.5 µm) to 100 mils (2.5 mm) in height and as small as 0.26 mils (6.6 µm) in width.

What is the field of view?

The 4D InSpec field of view is 1/3 x 1/3 in (8 x 8 mm). The field of view of 4D InSpec XL is 0.6 x 0.6 inches (15 x 15 mm).

What are the limitations for step height measurements?

For the 4D InSpec, the limitation on slopes and steps is that, from one pixel to the next, the height cannot change
by more than 180 micrometers (.007”). For the 4D InSpec XL, the limitation is 340 micrometers (0.013”)

Read our Application Note, Step Limitations of Fringe-Based Measurement Systems,” for more information on step height measurements.

Can I incorporate the 4D InSpec into an automated inspection station?

Yes. From a hardware standpoint, each 4D InSpec comes with a standard mounting bracket that is ideal for mounting the unit into an automated inspection station. Integration with UR cobots is native to the software, and is built into the interface. We also offer an optional 4D InSpec Software Development Kit (SDK) which enables test system integrators and end users to readily integrate the 4D InSpec into a larger system with other software and/or automation functions.

4D can also provide assistance to help integrate the 4D InSpec’s control and measurement software into an OEM’s control PC for automated inspection. We also offer optional consulting to help with the integration effort, if necessary.

What types of file outputs does the 4D InSpec support?

The 4D InSpec writes the surface and measurement information to a standard .csv or binary .opd file that stores measurement setup information as well as surface height data. This file may be used for post-acquisition analysis in other analysis software packages. File information includes time, date, key measurement setup parameters, and the 3D point cloud information for each measurement. Defect information may also be saved separately from the full surface map in a .csv file for easy import into production control software.

How often do I need to recalibrate the system?

Calibration is almost never required with the 4D InSpec. The unique optical method employed by the 4D InSpec intrinsically creates and maintains the system’s lateral and vertical accuracy. Each 4D InSpec system is certified at the factory. And 4D InSpec systems should not require recalibration to maintain the system’s accuracy over its useful life. A traceable calibration verification function is available, however. A system user or local calibration lab may employ the procedure and the standard to verify performance and accuracy per local quality control policies. View our “4D InSpec Calibration”  video to learn about the fast, simple method for calibrating the instrument.

How easy is it to install the 4D InSpec?

With a single cable and no moving parts, the 4D InSpec sets up in just a few minutes. View the “Surface Gauge Installation Video”  to see how easily the system can be installed.

How rugged is a 4D InSpec?

The 4D InSpec is designed for technician use in a normal workshop environment with non-condensing operating temperatures from 10–30 °C to (50–86 °F). The system should be allowed to settle its temperature before use. Also, the 4D InSpec is designed to meet the Ingress Protection Level of IP53: Protected from significant dust ingress, and moderate exposure to liquids.

Please note the 4D InSpec is not waterproof.

Can the 4D InSpec be workstation or robot mounted?

The 4D InSpec can be handheld for portable measurement of large components, or mounted in a workstation stand for repeatable QC measurements. Measurements with the instrument are not orientation-sensitive. It’ll measure vertically, sideways and even upside-down.

The 4D InSpec can also be mounted on a robot for fast, repeatable measurement over complex geometries. View our Watch this video to see the 4D InSpec in action as part of a robotic setup.

Can we use our own computer with the 4D InSpec?

While we recommend using computers supplied by 4D Technology to ensure maximum performance, we recognize that some organizations are required to use their own internally-qualified computers for security purposes. Minimum recommended computer and display specifications are as follows:
– 500GB Hard drive
– 8GB 1600MHz DDR3L memory
– 15.6 inch UltraSharp FHD (1920 x 1080) display. Touchscreen is highly preferred.
– Intel Core i7-4810MQ Processor (Quad Core 2.80GHz, 3.80 GHz Turbo, 6MB 47W, w/ HD Graphics 4600)
– 1 USB 3.0 port
– Windows 64-bit OS

– Strongly recommended: on-board GigE Ethernet NIC card with the Intel Pro1000 chipset.


How long an Ethernet cord can I use with the 4D InSpec?

The standard cord is 3m (10 feet) long. The InSpec has been tested to operate with cords up to 50 feet in length.

Get In Touch

(520) 294-5600


3280 E Hemisphere Loop, Ste 146
Tucson, AZ 85706


Office Hours (Arizona Time)

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Wed: 8am - 5pm
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