What is a spectral confocal displacement sensor?

Spectral confocal displacement sensors are high-precision measurement devices based on confocal and spectral analysis technologies, designed for non-contact measurement of object parameters such as displacement, shape, and thickness. They achieve high-accuracy measurements by analyzing the focal positions of light at different wavelengths.

How does a spectral confocal displacement sensor work?

1. Multi-wavelength beam emission: The internal light source (typically a white LED or supercontinuum light source) emits a composite beam encompassing a broad range of wavelengths. These distinct wavelengths pass through a specialized optical system, propagating along the same optical axis while each wavelength converges at its specific focal point. 

2. Confocal spatial filtering: Upon reaching the surface of the measured object, only the wavelength precisely aligned with its focal point is most effectively reflected back to the sensor. An internal confocal pinhole mechanism ensures that only light reflected from the focal point passes through, significantly suppressing stray light interference—a critical factor for achieving high-precision measurements.

3. Spectral Analysis and Position Calculation: The reflected light is received and analyzed by a high-resolution spectrometer. By precisely identifying the wavelength corresponding to spectral peaks and combining this with a pre-calibrated “wavelength-to-position” mapping, the system calculates the object's exact distance relative to the sensor. This entire process is completed within microseconds, enabling real-time dynamic measurement.

What applications are spectral confocal displacement sensors suitable for?

1. Semiconductor and Microelectronics Manufacturing: Sensors enable non-contact measurements with nanometer-level precision for wafer thickness measurement, chip package height inspection, and surface topography measurement of MEMS devices, preventing damage to fragile components.

2. Transparent and Multilayer Material Measurement: Unique optical properties allow precise thickness measurement of transparent materials such as glass, plastic films, and optical coatings, even enabling individual layer thickness measurement within multilayer structures.

3. Precision Machining: Used to measure geometric parameters like height differences, flatness, and concentricity in precision components. Particularly suited for highly reflective metal surfaces, mirrors, and other materials challenging for traditional sensors.

4. Biomedical and Research: Critical applications include medical device surface quality inspection, biological tissue section thickness measurement, and microdevice dimensional verification. Its non-contact nature prevents sample contamination.

5. Emerging Technology Fields: Demonstrates significant potential in emerging industrial sectors including 3D printing process monitoring, flexible electronic device inspection, and lithium battery electrode thickness measurement.

What advantages do spectral confocal displacement sensors offer over traditional displacement sensors?

1. Exceptional measurement accuracy: Capable of achieving sub-micron to nanometer-level precision—a standard beyond the reach of many traditional sensors. The latest high-end spectral confocal sensors deliver resolutions below 10 nanometers.

2. True non-contact measurement: Completely eliminates the need for physical contact with the object being measured, preventing damage to soft, deformable, or high-precision surfaces while also eliminating measurement errors caused by probe wear.

3. Outstanding material adaptability: Unaffected by material color, transparency, or reflectivity. Accurate measurements are achievable on highly reflective metal mirrors, transparent glass and plastics, or light-absorbing black rubber.

4. Robust handling of complex surfaces: Capable of measuring inclined surfaces, stepped structures, micro-pores, and other intricate geometries with less stringent angle requirements than laser triangulation.

5. High-speed dynamic measurement capability: Rapid response time enables real-time online inspection and dynamic process monitoring, meeting the high-speed measurement demands of modern automated production lines.

How to Select the Right Spectral Confocal Displacement Sensor?

1. Define measurement requirements

• Measurement Range: Select an appropriate range based on the maximum possible displacement or thickness variation of the object being measured.

• Accuracy Requirements: Specify the required resolution (minimum detectable change) and accuracy (consistency with the true value).

• Measurement Speed: Determine the required sampling rate based on the production line cycle time or inspection frequency.

2. Consider the Characteristics of the Tested Object

• Material Type: Verify whether the sensor is suitable for the color, transparency, and reflective properties of the material being measured.

• Surface Condition: Rough surfaces may require a specialized sensor model.

• Working Distance: Select an appropriate sensor working distance based on installation space constraints.

3. Evaluating Environmental Conditions

• Temperature Stability: Temperature fluctuations in industrial environments may affect measurement accuracy; temperature compensation functionality should be considered.

• Vibration Environment: High-vibration environments may require selecting models with superior vibration resistance.

• Space Constraints: Compact spaces necessitate choosing miniaturized probes.

4. System Integration Factors

• Output Interface: Verify compatibility of sensor analog, digital, or bus interfaces with existing systems

• Software Functionality: Confirm whether supporting software provides required data processing, analysis, and visualization capabilities

• Installation Method: Consider mechanical integration aspects such as probe mounting angle and fixation methods