Maintenance of spark direct reading spectrometer
The direct reading spectrometer is a precision instrument combining light and electricity. Proper use and maintenance are the key to the normal operation of the machine, prolonging the service life, and maintaining high performance and high performance. Be sure to follow the instrument manual to fully understand the whole process from principle to actual operation and testing. It is necessary to oppose mystification and to oppose blindness. We must use our strengths in understanding the optical, mechanical, and electronic (including computer) aspects of the instrument, so that we can benefit from deep knowledge and long-term experience, and use theory to guide practical operations. If the performance of the instrument is not digested, it will cause damaging damage. Even if a different part is slightly moved, sometimes it will not be detected, which will affect the use and affect the analysis time. Even if it is detected, it needs to be verified. Go up.
Instrument maintenance should be done with three defenses and one constant. That is, shockproof, dustproof, and moisture-proof, the instrument should be kept at a constant temperature. This condition must be considered in the design laboratory.
To maintain high sensitivity (low detection limit) and high accuracy of the instrument test results. (Based on the standard deviation of the detection limit is background/noise) or two standard deviations or three standard deviations (the national standard specifies three standard deviations). It can be seen that the detection limit of noise is low. Therefore, the signal-to-noise ratio of the whole system should be high. To be stable (refer to reproducibility), it is necessary to start from the light source, the optical splitter and the measurement and control system. If the room in which the instrument is placed is close to or impacted by the source, the coaxiality of the entire system and its relative position are destroyed. In severe cases, the signal to be measured cannot be measured or the signal is weak, and the stray light is increased. The temperature coefficient of the internal components and components of the instrument changes due to changes in temperature. Since the temperature coefficient of other components and components of the instrument varies with temperature, the relative position of each component changes. The change in temperature causes the refractive index of the optical components inside the instrument; the refractive index of the dispersive element and the change in the grating constant cause a change in the grating dispersion rate. This causes the spectral line (image of the incident) to deviate from the center of the exit slit, affecting the sharpness or intensity of the spectral line.
The light emitted from the light source, the optical effective space passing through the beam splitter to the detector window, the transmissive surface, and the reflective surface are contaminated by dust, fingerprints, moisture, oil, mildew, and the like. The signal is attenuated by absorption, reflection, and scattering losses. Some have increased the background and increased the noise level.
Electrical components (especially high-voltage high-frequency components) may also cause excessive dielectric loss due to dust, moisture, oil, and excessive temperature, resulting in reduced insulation, increased dark current, and severe breakdown, damage, and leakage. The lighter will also deteriorate the stability of the instrument, increase the thermal noise electrons, and reduce the signal-to-noise ratio.
Commonly used optical components such as crystal, lead film, silver film and other mirrors, after a period of time on the grating reflection surface, the reflectivity and transmittance are reduced. This phenomenon occurs when placed in the atmosphere for a long time. Severe can produce mildew. It is because the growth and development temperature of mold is between 10 °C and 40 °C, more than 70% humidity and dust (the dust itself is organic matter and mold), organic gaskets, paints, organic oils, adhesives, etc. introduced inside the instrument. It is the nutrition of mold growth and reproduction.
The harm of mold to optical instruments is very serious, which greatly reduces the transmittance, reflectivity, light guide and image quality of light. Therefore, the photoelectric direct reading spectrometer should select the instrument with internal temperature control as much as possible; generally, the indoor control temperature is about 23 °C. The instrument should be placed in a room that is not exposed to direct sunlight and that is shock-proof, dust-free, dry, with small temperature changes and away from corrosive atmospheres.