JPH0251876B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an FZ device (intensive infrared heating single crystal manufacturing device), and in particular, a device for automatically growing crystals.
Regarding FZ equipment.

[Prior art]

Conventionally, crystal synthesis in the FZ apparatus was not automatically controlled, and the only way to do so was to observe the image on a screen through a hole provided in one location of the spheroidal mirror.

Therefore, in order to grow crystals, it was necessary to constantly monitor images and manually adjust the lamp power or gap.

〔the purpose〕

The present invention solves the above problems, and its purpose is to provide an FZ apparatus that can stably grow crystals for a long time (10 hours or more).

〔overview〕

The FZ device of the present invention is provided with a filter and an aperture in the middle of an optical system such as a lens, prism, half mirror, and reflecting mirror, and an image of the molten zone is transmitted through a hole provided in a part of the spheroidal mirror to the optical system. The crystal is automatically grown by forming an image on an optical sensor through a system and processing the signal from the optical sensor, and is characterized by a high signal-to-noise ratio of the signal in the optical sensor and high control accuracy. .

Figure 1 shows an overview of the previous FZ device.

Here, 1 is a spheroidal mirror, 2 is a halogen lamp, 3 is a quartz tube, 4 is a gas inlet, 5 is a gas outlet, 6 is a raw material rod, 7 is a seed crystal, 8 is a melt, 9 is an upper shaft , 10 is a lower shaft, 11 is a lens (including a prism), and 12 is a screen.

A raw material rod 6 is set on the upper shaft 9, and a seed crystal 7 is set on the lower shaft 10.

The power of the halogen lamp 2 is turned on, and the spheroidal mirror 1 focuses the light from the halogen lamp onto the center of the quartz tube 3.

At this time, atmospheric gas is introduced through the gas inlet 4 and exhausted through the gas exhaust port 5.

In the light condensing section, the tip of the raw material rod 6 and the tip of the seed crystal 7 are brought into molten contact to form a molten zone 8.
At this time, the upper shaft 9 and the lower shaft 10
are rotated in the same direction or in opposite directions, and the upper and lower shafts move downward at the same time.

The state of the light condensing section is projected onto the screen 12 via the lens 11 (including the prism) and the reflecting mirror, and while constantly monitoring the projected image, the lamp power or the gap between the raw material rod and the seed crystal is adjusted. Crystal growth is performed while making adjustments.

Figure 2 shows an overview of the optical system of the previous FZ device.
Here, a is a plan view and b is a side view.

21 is a melting zone, 22 is a lens (including a prism),
23 is a reflecting mirror, 24 is a screen, and 25 is a front panel.

FIG. 3 shows a block diagram of the automatic control system used in the FZ device of the present invention.

Here, 31 is an optical system, 32 is a sensor section, 33 is a controller section, 34 is a key input section, and 35 is a DA
Converter, 36 is an AD converter, 37 is a display unit, 38
39 is a lamp power control section, and 40 is a gap adjustment section.

The image of the melted zone passes through the optical system 31 and is sent to the sensor section 3.
2, the control section 39 adjusts the lamp power to control the temperature of the melting zone, or the gap adjustment section 40 adjusts the height of the melt.

The lamp power or gap is fed back to the controller section 33 via the AD converter 36.

On the other hand, the key input section 34 inputs various initial constants, and the display section 37 displays the lamp power and the like at that time. Further, the printer section 38 prints out the lamp power, melting zone diameter, melting zone height, etc. at predetermined intervals.

When performing automatic control, the signal-to-noise ratio of the signal in the optical sensor has a very large effect on subsequent calculation processing, and a high signal-to-noise ratio is an essential condition.

〔Example〕

Hereinafter, the present invention will be described in detail based on examples.

FIGS. 4 and 5 show plan views of the optical system of the apparatus of the present invention.

Here, 41 and 51 are melting zones, 42 and 52 are filters, 43 and 53 are lenses (including prisms), 44 and 45 are apertures, 45 and 55 are optical sensors, 46 and 56 are front panels, 57 is a half mirror, 58 is a reflecting mirror, and 59 is a screen.

FIG. 6 shows a signal waveform obtained by an oscilloscope when a line sensor is used as an optical sensor and arithmetic processing is performed.

Here, 61 is a direct value of the light amount level of the sensor, and 62 is a value obtained by converting this into a binary value.

(a) is when the aperture is closed down too much, (b) is the appropriate value, and (c) is when the aperture is opened too much.

If the aperture in (a) is closed down too much, the binary signal will be cut off in the middle as shown in Since the value increases at the ends like Y, the determination at both ends of the diameter becomes inaccurate.

The required power varies depending on the material of the crystal, so
Although the brightness of the melting zone changes, the present invention can cope with this by changing the filter and changing the opening/closing status of the aperture.

〔effect〕

As described above, according to the present invention, by providing the filter on the melting zone side of the lens and the diaphragm on the opposite side of the lens to the melting zone, it is possible to easily replace the filter or open and close the filter at the end. As a result, a signal with a high signal-to-noise ratio can be given to the optical system, so even if the material used for growing the crystal changes, operations that match the material can be performed, so an appropriate signal level can be obtained and long-term operation can be performed. It is possible to grow stable crystals even if the system is operated unattended for hours. Therefore, not only gemstone single crystals such as ruby, sapphire, and alexandrite, but also YIG,
It can also be used for industrial single crystals such as YAG and GGG, and can grow high-quality single crystals without uneven color, bubbles, defects, etc.

[Brief explanation of drawings]

Figure 1 shows an overview of the conventional FZ device. Figure 2 shows an overview of the optical system of the conventional FZ device. FIG. 3 shows a block diagram of the automatic control system used in the FZ device of the present invention. FIG. 4 shows an outline of the optical system of the FZ device of the present invention. FIG. 5 shows an outline of another optical system of the FZ device of the present invention. Figure 6 shows the present invention.
When using a line sensor in FZ equipment,
Shows the signal waveform.

Claims (1)

[Claims] 1 An image of the molten zone is formed on an optical sensor through an optical system such as a lens, prism, half mirror, or reflector through a hole provided in a part of the spheroidal mirror, and the diameter or external shape of the molten zone is determined. In an infrared condensed heating single crystal manufacturing apparatus that automatically controls the lamp power or the height of the melting zone by measuring the temperature, the optical system includes a filter on the melting zone side of the optical system and a filter on the opposite side of the optical system to the melting zone. An infrared condensed heating single crystal production device characterized by having an aperture.