White Light Confocal Sensor Technology for High Precision Measurement on Practically All Surface Types
The CCS Prima Confocal displacement sensors use a white light source to accurately measure the distance to surfaces. The essence of the principle is the accurate detection of colors from light that is reflected back from target surfaces. The white light is focused onto the target surface by a multi-lens optical system. These lenses disperse the light into monochromatic stages (colors) along the measurement axis. A specific distance to the target is assigned to each color’s wavelength in a factory calibration. Only the wavelength which is exactly focused on the target is used for the measurement. This light reflected from the target surface is transmitted from the probe, through a confocal aperture and onto a spectrometer which detects and processes the spectral changes and calculates distances.
This technology permits measurement and profile of difficult transparent materials such as glass, lenses, liquids, etc.
Controllers for High Resolutions and Speeds
Unlike the other Acuity distance sensors, the Prima Confocal systems are comprised of an optical measurement “pen” and a separate controller. This controller houses all of the electronics, light source, etc. Acuity offers controllers that fit single or multiple pens that can achieve sampling rates up to 10kHz. The input/output options are RS232, RS422, USB and analog out.
Different Measurement Pens for Tough Applications
Chromatic-Confocal Sensor (CCS) pens are offered in a variety of measurement ranges and standoff distances, each with corresponding resolutions. Available pen options include modular, endoscopic, interferometric, and 90-degree pens. Acuity’s different selection of pen options satisfy measurement ranges up to 24mm, linearity down to 35 microns, and axial resolution down to 5 nanometers.
Built for Difficult Applications
Confocal sensors are typically preferred when laser displacement sensors are not able to make a measurement on a difficult target, make a measurement inside a tight space, or able to achieve a measurement with enough precision. The following are a few application examples:
One sided glass thickness – white light technology enables precise measurement for transparent surfaces such as glass. Multi layered glass thickness can also be measured using one probe from one side.
Measurement of all types of surfaces – white light technology principle to satisfy measurement of transparent, opaque, polished or rough materials.
Measurement in tiny or difficult spaces –available pen options include pens with spot sizes less than 3 microns, pen options for large tilt angles, and 90-degree pens options. These versatile pen options are built for measurement in tight spaces or difficult, hard to reach applications.
CCS Prima Confocal Displacement Sensor Case Studies
Acuity White Light Confocal Medical Scans
An Acuity medical customer is using the Initial 4.0 model to create a 3D scan of medical samples to measure the change in the surface features. This technology is able to measure on any target surface including clear and mirror surfaces.
Bow and Warp Measurement of Silicon Wafers Using Confocal Sensors
In the production of silicon wafers, manufacturers are particularly concerned with bow, warp and overall flatness of the substrates. Wafer manufacturers use confocal sensors in their custom inspection systems to precisely measure the 2D flatness profile of each wafer.
Brake Line Tip Inspection
Engineers frequently use a precision scanning confocal displacement sensor to inspect the surface of a steel brake line tip for scratches and defects.
Clear Film Thickness Measurement
One of Acuity’s existing customers wanted to be able to measure the thickness of a clear and semi-transparent film online. By using the white light confocal chromatic CL4 MG35 probe on a CCS Prima controller, the customer was able to hold +/- 0.6 microns of thickness accuracy.
Clear Polymer Thickness Measurement
A manufacturer of a clear polymer used to make food wrapping material is using white light confocal probing to measure the thickness of the material as it’s being made.
