JPH0125476Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a sample cooling device for an electron microscope or the like.

Generally speaking, the sample cooling device in a so-called side-entry type sample device, in which the sample is inserted from the direction perpendicular to the optical axis, cools the sample through a flexible pipe using a coolant, such as liquid nitrogen, in a cooling tank installed outside the microscope body. A method has been adopted in which the sample is cooled by directly guiding it to the vicinity.

However, such devices are only capable of cooling the temperature of liquid nitrogen, and cannot be varied over a wide range, for example, from the temperature of liquid nitrogen to a relatively high temperature of about -100°C. do not have. Conventionally, when trying to cool a sample to an extremely low temperature, the refrigerant liquid is guided to the vicinity of the sample, and when the cooling of the sample is to be moderated, the switching valve is switched to bring the refrigerant to the vicinity of the sample. By introducing refrigerant gas instead of refrigerant liquid, the cooling temperature of the sample can be varied over a relatively wide range. However, in such conventional devices, it is necessary to separately provide a refrigerant liquid tank for supplying refrigerant liquid and a refrigerant gas container for supplying refrigerant gas, and it is necessary to separately provide a refrigerant liquid tank and a refrigerant gas container for supplying refrigerant gas. In order to make adjustments, separate adjustment mechanisms were required for each refrigerant liquid and refrigerant gas. As a result, the device becomes complicated, and the manufacturing cost of the device also increases accordingly.

The purpose of the present invention is to solve these conventional drawbacks and provide a sample cooling device for electron microscopes, etc., which has a simple structure and low manufacturing cost. is arranged, a pipe for introducing a refrigerant into the cooling member and a pipe for discharging the introduced refrigerant, and a cooling tank for accommodating the refrigerant liquid, A switching valve having two inlet holes and one outlet hole is provided in the cooling tank,
One introduction hole of the switching valve communicates with the refrigerant liquid, and the other introduction hole communicates with the refrigerant gas atmosphere existing between the refrigerant liquid level and the top surface of the cooling tank, and the introduction pipe One end is inserted into the cooling tank and connected to the outlet hole in order to receive refrigerant supply, and means for operating the valve body from outside the cooling tank to switch the introduction hole connected to the outlet hole. The cooling tank is closed to the atmosphere so that the refrigerant liquid and refrigerant gas can be supplied to the introduction hole by the pressure of the refrigerant gas generated in the cooling tank. In addition, a heater is provided in the cooling tank to adjust the gas pressure and the amount of refrigerant to be transported to the heat conduction rod.

Hereinafter, one embodiment of the present invention will be explained in detail based on the drawings.

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the present invention, in which numeral 1 denotes a sample holder which is held in a mirror body 2 of an electron microscope so that it can be inserted into and removed from a direction perpendicular to the optical axis; is formed into a plate shape and placed between the upper magnetic pole 3a and the lower magnetic pole 3b of the objective lens, and a sample stage 5 holding the sample 4 is placed on a thermally insulated glass bulb or the like at the part intersecting the optical axis. It is installed in a state where it is thermally isolated through a section. 6 is an outer tank installed in the atmosphere, and a cooling tank 8 filled with liquid nitrogen 7 inside.
is installed in a thermally isolated state. 9 is a flexible pipe for guiding the liquid nitrogen 7 to a portion of the cooling member 10 that is thermally connected to the sample 4;
A bellows 11 is provided in the middle of the pipe,
This prevents vibrations of the cooling tank 8 due to evaporation of liquid nitrogen from being transmitted to the sample 4. Further, the outer periphery of the pipe is covered with an outer cylinder 13 having a bellows 12 to form a double pipe structure, and by keeping the space in a vacuum, heat inflow is prevented. 14 is a switching valve, and 14a is a valve body. One end of the valve element 14a is connected to an operating shaft 15 taken out from the cooling tank 8, and is moved up and down by the operating shaft 15 and used for switching the valve. As shown in more detail in FIG. 2, the operating shaft 15 is formed into a pipe shape, and also serves as one of the introduction holes of the switching valve. That is, the pipe-shaped operating shaft 15 has a hole 18, and nitrogen gas generated by vaporization exists between the liquid level of the liquid nitrogen 7 and the upper surface of the cooling tank 8.
The hole 18 is located in a position communicating with this vaporized gas atmosphere. A hole 17 is provided at the lower end of the pipe-shaped operating shaft 15, and the hole 17 communicates with the valve chamber 14b. The valve chamber 14b communicates with liquid nitrogen through a hole 16, which serves as the other introduction hole communicating with the valve chamber 14b. One end of the pipe 9 is inserted into the cooling tank 8 and connected to an outlet hole of the valve chamber 14b in order to receive supply of liquid nitrogen or vaporized gas. When the valve body 14a is located on the upper side by operating the operating shaft 15, the hole 17 is closed and the hole 1 is closed.
6 is opened, the hole 16 is opened through the valve chamber 14b.
and pipe 9 are connected, and liquid nitrogen 7 is supplied to cooling member 1.
0, and when the valve body 14a is located at the lower side by operating the shaft 15 as in the state shown in FIG. 2, the hole 16 is closed and the hole 17 is opened. and pipe 9 are connected to send nitrogen gas to the cooling member. Due to the pressure of nitrogen gas generated in the cooling tank 8, the cooling tank 17 is closed to the atmosphere to the extent that liquid nitrogen can be supplied to the holes 16 and nitrogen gas can be supplied to the holes 18. has been done. Further, in order to adjust the gas pressure of nitrogen gas and the amount of refrigerant transported to the cooling member 10, a heater 21 is placed in the liquid nitrogen in the cooling tank 8. 19 is a needle valve for controlling the flow rate of the refrigerant by controlling the diameter of the transport path. 20 is an introduction pipe for supplying liquid nitrogen to the cooling tank 8.

The connection part B between the sample holder 1 and the pipe 9 is
As shown in an enlarged view in FIG. 3, the cap nut 2 is rotatably connected via bearings 21 and 22
The pipe 9 can be removed by loosening the pipe 3. Thereby, the sample holder 1 can be freely rotated and the sample 4 can be tilted regardless of the pipe 9. Reference numeral 24 denotes an O-ring packing for insulating the connecting part (bearing part) between the sample holder 1 and the pipe 9 from the atmosphere, and is used to prevent water droplets and frost from adhering to the bearing part. 25 is a recovery pipe for recovering liquid nitrogen and its vaporized gas that have reached the cooling member 10.

In order to start cooling the sample, first, the switching valve 14 is positioned downward and the vaporized gas in the cooling tank 8 is supplied to the pipe 9.
Bellows 11, cooling member 10 and recovery pipe 25
Pre-cool. After that, if the switching valve 14 is moved upward, the liquid nitrogen 7 is sent directly to the cooling member 10 through the pipe 9, so that the sample 4 can be cooled to the liquid nitrogen temperature (approximately -180°C).
On the other hand, if the switching valve 14 is moved downward in this state, the vaporized gas is sent to the cooling member, so that the sample is maintained at a relatively high cooling temperature (about -100°C). Further, in order to achieve a temperature between the liquid nitrogen temperature (about -180°C) and the vaporized gas temperature (about -100°C), the flow rate of liquid nitrogen or nitrogen gas may be adjusted. This adjustment is performed by adjusting the heating current to the heater 21 to adjust the rate of vaporization and adjust the pressure of the nitrogen gas. in this case,
By controlling the amount of opening and closing of the needle valve 19, the flow rate can be adjusted more precisely.

As is clear from the above description, in the present invention, a switching valve having two inlet holes and one outlet hole is provided in the cooling tank, and one of the inlet holes of the switching valve is connected to the refrigerant liquid. The other inlet hole is in communication with the refrigerant gas atmosphere existing between the refrigerant liquid level and the upper surface of the cooling tank, and one end of the inlet pipe is connected to the cooling tank to receive the refrigerant supply. The valve body is inserted into the tank and connected to the outlet hole, and is provided with means for operating the valve body from outside the cooling tank in order to switch the introduction hole connected to the outlet hole. The cooling tank is closed to the atmosphere so that the refrigerant liquid and refrigerant gas can be supplied to the introduction hole by the pressure of the refrigerant gas generated, and the gas pressure is adjusted to reduce the heat. Since the configuration is equipped with a heater to adjust the amount of refrigerant transported to the conduction rod, there is no need to provide separate refrigerant liquid tanks and refrigerant gas tanks, or separate flow rate adjustment means for refrigerant liquid and refrigerant gas. By using a single cooling tank and a single heater to adjust the flow rate, one of the refrigerant liquid and refrigerant gas can be switched arbitrarily and sent to the sample cooling member while adjusting the flow rate. . Therefore, the present invention provides a sample cooling device for an electron microscope or the like that has a simple structure and can reduce manufacturing costs.

With the above configuration, the temperature of the sample can be arbitrarily adjusted over a wide range from -180°C to a relatively high temperature of about -100°C by simply moving the switching valve without incorporating a heater into the sample holding part. Since it can be varied, it is possible to simplify the structure and reduce costs, and also has the effect of preventing wasteful consumption of liquid nitrogen, which is highly practical.

In the above description, the sample was cooled with liquid nitrogen, but the sample is not limited to this, and the sample may be cooled with other coolants, such as liquid helium. Furthermore, although the case has been described in which the present invention is implemented in a side entry type sample device, it can also be implemented in a so-called top entry type in which the sample is inserted from the optical axis direction. Further, although the case where the method is applied to an electron microscope has been described, it goes without saying that the method can be applied to a scanning electron microscope as well.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention, and FIGS. 2 and 3 are partially enlarged sectional views of FIG. 1, respectively. 1: Sample holder, 2: Mirror body, 3a: Upper magnetic pole of objective lens, 3b: Lower magnetic pole of objective lens, 4: Sample, 5: Sample stage, 6: Outer tank, 7: Liquid nitrogen, 8:
Cooling tank, 9: Pipe, 10: Cooling member, 11, 1
2: bellows, 13: outer cylinder, 14: switching valve, 1
5: Operation shaft, 16, 17, 18: Hole, 19: Needle valve.

Claims (1)

[Scope of utility model registration request] A cooling member thermally connected to the sample is arranged, a pipe for introducing a refrigerant into the cooling member and a pipe for discharging the introduced refrigerant are provided, and the refrigerant liquid is accommodated. The cooling tank is equipped with two inlet holes and one
A switching valve having two outlet holes is provided, one introduction hole of the switching valve communicates with the refrigerant liquid, and the other introduction hole exists between the refrigerant liquid level and the top surface of the cooling tank. The introduction pipe is connected to a refrigerant gas atmosphere, and one end of the introduction pipe is inserted into the cooling tank and connected to the outlet hole in order to receive a supply of refrigerant, and the introduction hole connected to the outlet hole is connected to the outlet hole. A means for operating the valve body from outside the cooling tank is provided for switching, and the refrigerant liquid and refrigerant gas can be supplied to the introduction hole by the pressure of the refrigerant gas generated in the cooling tank. The cooling tank is closed to the atmosphere, and the cooling tank is equipped with a heater for adjusting the gas pressure and the amount of refrigerant to be transported to the cooling member. Features: Sample cooling device for electron microscopes, etc.