Why should the background be measured first when using laser particle size analyzer?

Why should the background be measured first when using laser particle size analyzer?

The background is the fixed optical signal formed on the detector after the laser passes through the pure medium, which is mainly caused by the scattering of light caused by particles on the path of the detection light (for example, stains on the surface of the sample pool window glass and lens, internal defects, residual particles in the medium, etc.). The purpose of the measurement background in the particle size test (with samples) is to deduct these fixed, sampler independent signals in order to eliminate the impact of stray light other than sample scattering on the test results.

What are the factors that affect the background value of laser particle size meter?

If the background value of the laser particle size meter is high on most detectors, and the first and second units near the center are normal, the reasons are usually stains on the glass of the sample pool, dust on the lens, residual particles in the medium, fog drops on the outer surface of the glass caused by the medium temperature below room temperature. If the detection unit near the center of the detector, especially unit 1 and unit 2, is too high, it is generally caused by poor alignment of the beam. If the background signal of all detection units is too low, it is likely to be caused by laser power reduction or filter pinhole deviation. After finding out the reasons causing the background signal to be too high or too low, the above problems should be eliminated, so that the background strength will return to the normal state.