In fact, in order to ensure the accuracy of each measurement result, almost all measuring equipment or systems need to be calibrated before use. Although the measuring equipment and system have gone through a rigorous calibration process before leaving the factory, this is not once and for all, with the change of temperature, humidity, vibration and light and other factors in the use environment, the measuring equipment and system may be interfered with, and the measurement accuracy will be greatly affected. When using a spectral confocal measuring device or system, a calibration process should be carried out in order to ensure measurement accuracy. The following Shenzhen Liyi will introduce the calibration method of spectral confocal sensor in detail with you:

Why is calibration needed

According to the measurement principle of spectral confocal, the controller needs to analyze the reflected spectral signal. However, the sensor in the controller can still detect some signals without measuring the sample. These signals, often referred to as dark signals, consist of stray light reflected back from the fiber coupler and measuring head.

When the sample is measured, the spectral signal received by the controller is actually composed of a dark signal and a reflection signal from the sample surface, and the latter signal is what we really need. Therefore, in order to obtain the surface reflection signal of the prepared sample, we need to collect the dark signal in advance, and subtract the dark signal when processing the measurement data.

The method of dark signal processing is to collect the dark signal before the formal measurement, store the gray value information of each pixel of the sensor, and store the gray value of all pixels in RAM, and subtract the gray value in each measurement.

2. Calibration method

Start the device and wait 15 minutes until the machine reaches the state of thermal balance.

Raise the measuring head to ensure that there is no debris within the range. In order to achieve better treatment results, it is recommended to use a piece of white paper to completely cover the measuring head;

Press the dark signal processing button on the device operating software interface, or press the entity button of dark signal collection on the device panel, and wait for the light intensity and measurement signal indicator to blink to complete the dark signal collection process;

According to the color of the three LED signal indicators on the device panel, the dark signal processing result is determined. Green indicates that the dark signal level meets all the measurement frequency requirements; Orange indicates that the current dark signal level is too high, but can still meet high frequency measurement applications; Red indicates that the current dark signal level is too high, not suitable for measurement, should be re-dark signal acquisition process.

Iii. Calibration precautions

It is recommended to perform dark signal processing 15 minutes after the device is started, because the device is in thermal equilibrium at this time.

When the three LED signal indicators appear orange or red, it means that the current dark signal level is high, and the dark signal collection fault should be eliminated in accordance with the following three steps:

Reconfirm that there is no debris in the measuring range of the measuring head, and completely cover the measuring head with white paper to carry out the dark signal acquisition process and check the signal indicator status. If it shows orange or red, please continue to the next step;

Remove the optical fiber connector connecting to the measuring head from the controller panel and collect dark signals. If the LED indicator is green, it indicates that the problem is caused by the measuring head. The optical fiber connector connecting to the measuring head may be contaminated with dust. If the fault persists, the optical fiber may be damaged. You are advised to replace the optical fiber.

If the LED indicator is orange or red, it indicates that the fault originates from inside the controller. In this case, please notify technical support personnel to solve the problem. Do you understand the calibration method of spectral confocal sensor now? Shenzhen Liyi Technology Co., Ltd. is a professional production and sales of displacement sensor, laser displacement sensor, Angle displacement sensor, spectral confocal sensor company, in need of friends can call to consult Liyi fiber coaxial displacement sensor manufacturers. Welcome your call!