Apparatus for controlling thickness of digital optical film

Abstract

The invention relates to digital blooming thickness control instrument. It includes amplifier, filter, A / D module, embedded computing system, keyboard, display, switch, memory unit, and communicating interface. The amplifier is connected to reference signal, test signal, and filter. The filter is connected to A / D module. The embedded computing system is connected to A / D module, keyboard, display, switch, memory unit, and communicating interface. Its features are that the embedded computing system is set software program; and it practices control, tracing display, parameter setting and communicating according to initial setting value and keyboard entry. The invention has reasonable structure. And it is safe and reliable. It can use software to realize signal transformation, digital filtering, phase-locking and operation, reduce electron circuit mutual interference, and increase the complete machine anti-jamming capability and blooming production qualification rate.

Description

Technical field: [0001] The invention relates to a digital optical film thickness controller, which is mainly used in the field of optical coating. Background technique: [0002] Optical thin films are widely used in scientific and technological fields such as spectral analysis, laser technology, chemical industry, aerospace, and large precision instruments. Accurate control of optical thin film thickness is a key technology for preparing optical thin films. The monitoring methods that people usually use mainly include optical monitoring method and quartz crystal oscillation monitoring method. Optical monitoring method is one of the most widely used optical film thickness control methods at present. It uses photoelectric photometry to directly measure the extreme value of film transmittance or reflectance to realize the control of optical film thickness. A typical optical thin film instrument is shown in Figure 1. [0003] The main reasons for the poor anti-interference ab...

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Problems solved by technology

[0003] The main reasons for the poor anti-interference ability and stability of the film thickness monitoring system of the existing optical monitoring method are:

[0004] 1. In the existing system, the structure in which the monitoring light is directly irradiated on the incident slit of the monochromator makes the system's anti-vibration ability and ability to eliminate stray light relatively weak, while the light source, photomultiplier tube and its power supply work stably Sex also affects the stability of the monitoring signal

Therefore, in the monitoring system, the film thickness monitoring system is required to have a high anti-disturbance ability, which cannot be achieved by the existing analog circuit optical thin film instrument.

[0005] 2. The reliability and stability of the analog circuit filtering processing of the existing analog circuit optical thin film instrument is low, and it is difficult to change the filtering parameters; while the analog phase-locked loop has problems such as DC zero drift, component saturation, and initial calibration is necessary

[0006] 3. For complex analog circuits, the quality of electronic components and the mutual interference between circuits will affect the signal processing; in addition, only the design of analog circuits cannot perform targeted and various algorithm processing on various signal errors , affecting the accuracy and stability of the monitoring signal

[0007] 4. The existing coating production process mainly relies on human eye observation and manual operation

Because the operator has human subjectivity and experience when working, especially near the extreme point, the light intensity signal changes very slowly. It is difficult to ensure the quality and repeatability of the coating if it is necessary to make a timely and accurate judgment.

[0008] 5. Some are equipped with computer control systems, most of which are composed of industrial computers or programmable controllers, and the hardware cost is high; and generally only used for final data processing and analysis, not signal processing

[0009] 6. There are single-chip microcomputers, and the whole machine is mainly designed with analog circuits. Due to functional limitations, it only performs digital sampling, conversion and transmission. It has not realized the control of extreme value method and fixed value method through algorithms to achieve true automatic judgment.

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