Keyence Rolls Out Telecentric Lenses for Inline Measurement

January 19, 2023 by Seth Price

Using a telecentric optical system, Keyence's new TM-X5000 series for automated dimensional measurements aims to enhance quality control in manufacturing with greater accuracy and speed.

Keyence has announced that they are offering a new tool for taking automated measurements using machine vision. The TM-X5000 series telecentric system is designed to take fine, high speed measurements and will benefit quality control operations in the manufacturing environment.


What is a Telecentric Lens?

The Keyence TM-X5000 series uses telecentric lenses, which locate the aperture at the focal point of the lens. This means light entering the lens will be parallel, limiting distortion around the edges. Most commercial camera lenses are not telecentric, meaning there is distortion from both the object’s distance from the lens and its apparent distance from the center of the lens. This also means the lens does not need to be focused in the same manner as a lens from a regular camera.

Telecentric lenses are the preferred optics for dimensional measurements as they have very little distortion. With telecentric lenses, edges are sharp and crisp, straight lines remain straight, and parallel features remain parallel, regardless of the distance from the lens. 

conventional lens has more distortion near edges than telecentric lens

The advantage of a telecentric lens. Image used courtesy of Keyence


The TM-X5000 Series 

Keyence's TM-X5000 series of measurement systems are designed to be installed along production lines to perform quality control measurements automatically. They are a backlit system, meaning a supplied light source shines across to an optical sensor. As objects pass into the field of view of the telecentric lens, it casts a shadow onto one sensor. The image is captured, analyzed and displayed. Any anomalies, such as burrs, misalignments, or out-of-specification dimensions, are identified.

Backlit systems for inspection purposes provide high contrast images with sharp edges, making distance, angle, pitch, and other such measurements clear. This type of system works for making two dimensional images, meaning objects where the light can clearly outline important features. Round objects, or objects with multiple fold symmetry, can be imaged in this fashion. 

This optical system can take measurements for objects up to 120 mm while still maintaining accuracy of measurements down to 0.2 μm. The system can also take measurements as quickly as 25 μs, meaning dimensions can be determined quickly and while in motion.


The TM-X5000 optical measurement system series

The TM-X5000 measurement system series. Image used courtesy of Keyence


Automated Quality Control

The TM-X5000, capable of taking up to 100 measurements at once, can be used for automated quality control. By taking multiple measurements at a time, it is significantly faster than manual measurements or performing one-at-a-time optical measurements. This is particularly advantageous for complex geometries or measuring dimensions on tiny or concave components where a set of calipers would not reach. 

The ability to take small measurements means that this system can be used to detect small chips and burrs, as well as surface defects and other blemishes that may affect operation of the final product. 


Measuring automotive teeth pulley

Keyence demonstrated the TM-X5000 by measuring the teeth on an automotive pulley. Image used courtesy of Keyence


The system can also be used to check or measure machine tooling. Drill bits, end mills, and other rotating tools are not always perfectly mounted concentrically in the machine, or sometimes they wear or bend. The TM-X5000 can be used to measure runout to determine how concentrically these tools will rotate, helping to improve overall quality of the final products.


Measurement with Keyence

With the use of a telecentric measurement system, Keyence seeks to simplify the measurement process with increased accuracy and automation. The four available models can be installed with or without an included base and have IP64 enclosure ratings for versatility and durability. 


Featured image used courtesy of Keyence