Structure and principle of light oscilloscope
Introduction
Light oscilloscope (lightbeamoscillograph): The measured parameters can be electrical quantities such as current or voltage, or various non-electrical quantities that have been converted into electrical quantities. For example, when used in conjunction with strain gauges in mechanical engineering, it can measure stress, strain, torque and vibration. wait. The optical oscilloscope uses a light beam to record. The light beam has no inertia and the optical recording has no friction. The optical amplification effect can also be improved by increasing the length of the optical arm. Compared with other recorders, the operating frequency of optical oscilloscopes is higher, up to 10,000 Hz, while the general pen recorder does not exceed 100 Hz, and the jet recorder does not exceed 1,000 Hz. It also has the advantages of high current sensitivity, low recording error, and the instrument is light and small. It is especially suitable to be made into a multi-line oscilloscope that can record several or dozens of different parameters at the same time. However, the waveform diagram can only be made after certain processing. appear, and the recording paper used is more expensive.
The first light oscilloscope appeared in the early 20th century. Beginning in the 1960s, ultraviolet direct recording paper was used, which greatly simplified the process of displaying waveforms and made the operation of oscilloscopes more convenient and reliable.
Structure and principles
A light oscilloscope consists of a measurement part and a recording part. The measurement part mainly consists of a magnetoelectric vibrator (see galvanometer) and an optical system. A reflector is installed on the movable part of the oscillator composed of coils and wires. After the light beam emitted by the light source (incandescent lamp or high-pressure mercury lamp) is reflected by the reflector, an image point is formed on the photosensitive recording paper by the optical system. When a current flows through the coil, the coil and the reflector are deflected with the wire as the axis, causing the light spot to move horizontally in a straight line on the photosensitive paper. The deflection and movement rate of the light spot are related to the input current and its rate of change. The photosensitive paper is driven by the paper feeding mechanism and moves longitudinally at a constant speed, which can reflect changes in time. The curve recorded on the photosensitive paper is the change process of the input current with time, and the recorded function form is y=f(t). The oscillators are generally made very small, and an optical oscilloscope can be equipped with multiple (up to 60) oscillators. By adjusting the position of each light spot electrically or mechanically, multiple variables can be recorded simultaneously or cross-recorded.
Performance and applications
The oscillator is a key part of the optical oscilloscope. Different models of oscillators have different natural frequencies, operating frequency ranges, sensitivities, and maximum allowable currents. When using it, select an appropriate vibrator according to the signal being measured. The recording error of a light oscilloscope is generally ±5%. The natural frequency of the oscillator can reach 15000Hz and can record current signals below 10000Hz. The measurement part is driven by current, and the input impedance is low, generally only a few tens of ohms. It is suitable for recording low internal resistance voltage signal sources or current signal sources. Optical oscilloscopes are mainly used to record the transient process of electric current, as well as record and analyze non-electrical quantities such as vibration and strain, and can also be used to observe physiological phenomena.
