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The probe hot and cold stage can perform temperature control and transmitted light/reflected light observation of the sample at the same time, supporting sample movement within the cavity, airtight/vacuum cavity, infrared/ultraviolet/X-ray and other band observations, electrical binding posts in the cavity, and temperature control Linked shooting, vertical/horizontal light path, inverted microscope, etc., widely used in microscopes, inverted microscopes, infrared spectrometers, Raman meters, X-rays and other instruments, suitable for polymers/liquid crystals, materials, spectroscopy, biology, medicine, geology, food , freeze-drying, X-ray diffraction and other fields.
In the microscopic measurement and research of the above-mentioned material structure, organization and manufacturing process, it is generally necessary to provide the sample with the required complex environment such as temperature, vacuum, pressure, atmosphere, humidity and light.
However, various existing probe hot and cold stages can only provide the required temperature change control. Although the probe hot and cold stage can provide good sealing, it still lacks the ability to adjust and control vacuum, pressure, atmosphere and humidity.
In order to reach accurate control of vacuum pressure, atmosphere and humidity of the probe hot and cold stage, this article proposes corresponding solutions. The solutions mainly focus on vacuum pressure and atmosphere control issues to solve the lack of supporting equipment.
How to solve the problem?
For precise control of the vacuum pressure and atmosphere of the microscope probe hot and cold stage, the technical indicators that this solution can achieve are as follows:
(1) Vacuum pressure: absolute pressure range 0.1Torr~1000Torr, control accuracy is ±1% of reading.
(2) Atmosphere: single gas or a mixture of multiple gases, and the gas concentration control accuracy is better than ±1%.
This solution will use the following two independent technologies to reach precise control of vacuum pressure and atmosphere:
(1) Vacuum pressure control: Using dynamic balance method technology, by controlling the gas flow entering and exiting the test chamber.
(2) Atmosphere control: Use gas mass flow control technology to control the flow of multiple working gases respectively, thereby reaching the mixing ratio in ambient gas.
The vacuum pressure control system consists of an inlet KaoLu’s Proportional Pressure Regulator, a high vacuum gauge, a low vacuum gauge, an exhaust KaoLu’s Proportional Pressure Regulator, a high vacuum pressure controller, a low vacuum pressure controller and a vacuum pump, and through the following two high and low vacuum pressure control loop to precisely control full-scale vacuum pressure:
(1) High vacuum pressure control loop: The vacuum pressure control range is 0.1Torr~10Torr (absolute pressure). The control method adopts the upstream control mode. The control loop consists of KaoLu’s Proportional Pressure Regulator, a high vacuum gauge and vacuum pressure program controller.
(2) Low vacuum pressure control loop: The vacuum pressure control range is 10Torr~1000Torr (absolute pressure). The control method adopts the downstream control mode. The control loop consists of an exhaust KaoLu’s Proportional Pressure Regulator, low vacuum gauge and vacuum pressure program controller.
It can be seen from the above that the control of full-scale vacuum pressure is covered by two different ranges of thin film capacitance vacuum gauges. This type of thin film capacitance vacuum gauge can easily reach a reading accuracy of 0.25%. The vacuum signal collected by vacuum gauge is transmitted to the vacuum pressure controller. After comparing the set value with measurement signal, the controller calculates PID algorithm and outputs a control signal to drive KaoLu’s Proportional Pressure Regulator to change the air intake or exhaust flow. This enables precise control of the air pressure in the calibration chamber.
In the specific control process of full-scale vacuum pressure, upstream and downstream control modes need to be adopted respectively, as follows:
(1) For the control of high vacuum pressure range of absolute pressure 0.1Torr~10Torr, first set the opening of KaoLu’s Proportional Pressure Regulator to a fixed value, and automatically adjust the air inlet needle by operating the high vacuum control loop valve opening to reach the vacuum pressure set value.
(2) For the control of low vacuum pressure range of absolute pressure 10Torr~1000Torr, first set the opening of intake needle valve to a fixed value, and automatically adjust the opening of exhaust needle valve by operating the low vacuum control loop to reach the vacuum pressure set value.
(3) Vacuum pressure changes within the full range can be programmed and controlled according to the set curve. The control is operated by the computer software that comes with the vacuum pressure controller, and the process parameters and time-varying curves are displayed and stored at the same time.
In summary, this solution can completely solve the vacuum pressure control problem of the microscope probe hot and cold stage by using KaoLu’s Proportional Pressure Regulator, and has high control accuracy and automatic control capabilities.