Optical ranging based transparent liquid level measuring device and method

Abstract

The invention provides an optical ranging based transparent liquid level measuring device and method. The device comprises a laser, a collimating lens, a receiving lens, a linear array photoelectric detector and a processing unit. The laser is used for producing laser which is collimated by the collimating lens to be emitted to the liquid level vertically. The receiving lens is used for receiving refracted light which is diffused by the container bottom and refracted by the liquid level and forming a light spot on the linear array photoelectric detector. The processing unit is used for performing calculation to obtain the liquid level value of the transparent liquid according to the focal length of the receiving lens, a first distance from the light spot to a principal optic axis of the receiving lens, a second distance from the light spot to the laser, a third distance from the laser to the transparent liquid bottom, the transparent liquid refractive index and the air refractive index. By means of the device and the method, the transparent liquid level can be measured.

Description

technical field [0001] The invention relates to the technical field of photoelectric measurement, in particular to a liquid level measuring device and a liquid level measuring method for transparent liquid based on optical distance measurement. Background technique [0002] The liquid level refers to the height of the liquid level of the liquid medium in the container (generally refers to the height relative to the bottom surface of the container). In industrial and agricultural production, the liquid level is a very important parameter. The volume, quality and other information of the liquid medium can be calculated from the liquid level combined with other parameters; in the process of storing and transporting the liquid medium, it is also necessary to monitor the liquid level at all times. Determine whether there is an accident such as a spill or a leak. Therefore, liquid level measurement is widely used in the fields of petroleum, chemical industry, medicine, food and b...

AI Technical Summary

Problems solved by technology

Direct-reading liquid level measurement is the simplest and most intuitive measurement method. It uses the principle of a connector to connect the liquid in the container with an observation tube with a scale, and reads the liquid level height through the scale. This method is simple and intuitive. , high reliability, low cost, and has been widely used in practice, but this method is read data manually, there are manual errors, and it is necessary to install an observation tube with a scale in advance, there are certain potential safety hazards

The buoyancy type measurement of liquid level is based on the principle of force balance. With the help of floating objects (which can float on the liquid surface when in balance), when the height of the liquid level changes, the floating object will move up and down with the liquid surface, so the displacement of the floating object can be measured. You can know the change of the liquid level. This method has a simple structure and low price, but this method needs to use multiple transmission parts, which has poor stability and reliability and limited accuracy.

The static pressure measurement liquid level is based on the pressure generated by the liquid's own gravity on the container wall. Since the static pressure generated by the liquid on the container wall is proportional to the liquid level, the liquid level can be calculated by measuring the pressure on the container wall. , this method needs to install a pressure sensor on the inner wall of the container, the operation is complicated and the cost is high, so its application is limited

Acoustic measurement of liquid level uses the propagation characteristics of ultrasonic waves in the medium. An ultrasonic reflector and receiver are installed on the top or bottom of the container. The emitted ultrasonic waves are reflected by the liquid surface and received by the receiver. According to the time difference between emission and reception, it can Measure the liquid level, this method does not contact with the medium, no mechanical transmission parts, good stability, but the structure is complicated and the price is relatively expensive

Laser measurement of liquid level is to emit laser light from the laser source to the liquid surface to be measured, and receive the reflected light after being reflected by the liquid surface. The time difference from emission to reception can be measured, and the liquid level can be calculated. However, this method can only measure opacity. liquid that reflects light

Images