JP2005227148A - Method of expanding dynamic range of sensor, and scanning type measuring instrument using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow measurement with an expanded dynamic range, without saturating an output of a sensor, in a scanning type measuring instrument for scanning a sample with respect to the sensor to measure a signal generated from the sample, using the sensor. <P>SOLUTION: This instrument is provided with a means for resetting an output of the sensor after measurement in each measuring position, and a means for adding a difference between an output value of the sensor after the reset and a measured data before the reset to the measured data in the next measuring position, as an off-set value, and the dynamic range is thereby expanded in the sensor of the scanning type measuring instrument. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for expanding the dynamic range of a sensor in a scanning measurement apparatus that scans a sample with respect to a sensor and measures a signal generated from the sample using the sensor.

In the measurement method of the conventional scanning measurement apparatus, a sample is scanned with respect to a sensor, a signal generated from the sample is measured, and the measured data is stored in a memory as it is. FIG. 5 is a flowchart showing a measurement method in a conventional scanning measurement apparatus. After moving the stage to the measurement position, signals generated from the sample are measured and collected by a sensor, and this data is stored. This procedure is repeated until the last measurement position is reached (see, for example, Non-Patent Document 1).
“Applied Physics Vol. 67, No. 4 (1998)” published by Japan Society of Applied Physics, Non-destructive evaluation of materials using superconducting quantum interference devices, P419, Fig. 2

  Conventionally, however, the sample is scanned with respect to the sensor, the signal from the sample is measured by the sensor, and the output of the sensor is simply collected as measurement data. Therefore, if the signal generated from the sample is too large, the sensor There was a problem that the output of was saturated. This problem is also likely to occur when using a sensor with a small dynamic range.

  Among the sensors, the type of sensor that integrates and outputs the amount of increase or decrease in the signal generated from the sample. When the sensor output is reset, the output returns to the initial state and returns to the state before integration. An example of such a sensor is a superconducting quantum interference device as a highly sensitive magnetic sensor. With this type of sensor, resetting the output before it saturates can avoid saturation of the output, but there is a problem that it is impossible to accurately measure the signal generated from the sample. It was.

  Therefore, the present invention is a scanning measurement apparatus that scans a sample with respect to a sensor and measures a signal generated from the sample using the sensor, and continues measurement by expanding the dynamic range without saturating the output of the sensor. The purpose is to let you.

  In order to solve the above-described problems, the present invention provides a measurement method of a scanning measurement apparatus that scans a sample with respect to a sensor and measures a signal generated from the sample using the sensor, and measures the signal at each measurement position. A step of resetting the output of the sensor later, and a step of adding the difference between the output value of the sensor after the reset and the measurement data before the reset to the measurement data at the next measurement position as an offset value It is said.

  Further, in the measurement method of the scanning measurement apparatus that scans the sample with respect to the sensor and measures the signal generated from the sample using the sensor, the present invention reduces the number of resets and shortens the measurement time. Resetting the sensor output only when the measurement data at each measurement position exceeds a preset range between the value when the sensor is reset and the value when the sensor is saturated; A step of adding the difference between the output value and the measurement data before resetting to the measurement data at the next measurement position as an offset value is provided.

The present invention also provides a scanning stage for scanning a sample, a sensor for measuring a signal generated from the sample, an A / D converter for converting the output of the sensor into digital data, and the A / D conversion. In a scanning type measuring device comprising a CPU for collecting the digital data from a measuring instrument as measurement data, and a memory for storing the measurement data collected in the CPU,
A sensor output reset circuit for resetting the output of the sensor is provided, the output of the sensor is reset after measuring the signal at each measurement position, and the difference between the output value of the sensor after reset and the measurement data before reset is calculated. The offset value is added to measurement data at the next measurement position.

The present invention also provides a scanning stage for scanning a sample, a sensor for measuring a signal generated from the sample, an A / D converter for converting the output of the sensor into digital data, and the A / D conversion. In a scanning type measuring device comprising a CPU for collecting the digital data from a measuring instrument as measurement data, and a memory for storing the measurement data collected in the CPU,
The sensor output is reset only when measurement data at each measurement position exceeds a preset range between a value when the sensor is reset and a value when the sensor is saturated.

  The method for expanding the dynamic range of a sensor of the present invention and the scanning measurement apparatus using the same can be used when measuring a sample that generates a signal with a large change or when using a sensor with a small dynamic range. There is an effect that measurement can be performed by expanding the dynamic range without saturating the output of the sensor.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 3 shows a configuration diagram of the scanning measurement apparatus of the present invention. A sample 6 is installed on the scanning stage 5, and a sensor 1 is installed on the sample 6 at a certain distance. The sensor 1 is connected to a sensor output reset circuit 2 that resets the output of the sensor. In addition, an A / D converter 3 is connected to the sensor 1, and measurement data is collected by the CPU 4. The measurement data is stored in the memory 7. A reset signal is output from the CPU 4 to the sensor output reset circuit 2, and the stage position is controlled by the control signal for the scanning stage 5. In this case, the data obtained by measuring the signal generated from the sample by the sensor and processing it is dependent on the relative position with the sensor, but there is no temporal change or can be ignored.
FIG. 1 is a flowchart showing a method for expanding the dynamic range of a sensor according to Embodiment 1 of the present invention.

  First, the offset value added to the measurement data at each measurement position is set to zero. Next, the scanning stage is moved to the measurement position, and data (A) is collected from the sensor. This data (A) and the offset value are added and stored as measurement data at this position. Thereafter, the sensor output is reset, data (B) is collected again from the sensor at this position, offset value + data (A) −data (B) is calculated, and adopted as a new offset value. Here, when the output value of the sensor after reset is already known, it is not necessary to measure the data (B). Thereafter, the stage is moved to the next measurement position, and the same measurement procedure is repeated until the last measurement position is reached.

  FIG. 2 is a flowchart illustrating a sensor dynamic range expansion method according to the second embodiment of the present invention.

  In the second embodiment, as in the first embodiment, the scanning measurement apparatus of the present invention shown in FIG. 3 is used.

  First, the offset value added to the measurement data at each measurement position is set to zero. Next, the scanning stage is moved to the measurement position, and data (A) is collected from the sensor. This data (A) and the offset value are added and stored as measurement data at this position. After this, if the data (A) is within the preset value range between the value when the sensor is reset and the value when it is saturated, it moves to the next measurement position and continues the measurement. In this case, the sensor output is reset, data (B) is collected again from the sensor at this position, offset value + data (A) −data (B) is calculated, and adopted as a new offset value. Here, when the output value of the sensor after reset is already known, it is not necessary to measure the data (B). Thereafter, the stage is moved to the next measurement position, and the same measurement procedure is repeated until the last measurement position is reached.

  FIG. 4 shows a graph example of data measured using the sensor dynamic range expansion method according to the second embodiment of the present invention.

  The horizontal axis represents the position of the scanning stage, and the vertical axis represents the signal generated from the sample and the signal measured by the sensor. When a signal is generated from the sample as indicated by the broken line 10, the signal detected by the sensor by the measurement method according to the present invention is measured as indicated by the solid line 11.

  The signal 10 generated from the sample exceeds the upper limit 12 of the measurement range of the sensor, and data exceeding the upper limit cannot be measured. However, if the sensor is reset when the preset value 13 is exceeded, it shifts from the data 14 measured before resetting as shown in the graph 11 to the value of the data 15 measured after resetting. The difference between the data 14 and the data 15 is stored as the offset value shown in FIG. 2 and added to the measurement data after the reset. Each time a new reset is performed, the offset value is added to the offset value stored at the previous reset, and then added to the subsequent measurement data. The signal 10 to be measured can be measured.

  As the sensor, a magnetic sensor or a superconducting quantum interference element may be used, and a sensor dynamic range expansion method corresponding to the description in the first and second embodiments and a scanning measurement apparatus using the same may be implemented. .

5 is a flowchart illustrating a method for expanding the dynamic range of the sensor according to the first embodiment of the invention. The flowchart which shows the dynamic range expansion method of the sensor which concerns on Example 2 of this invention. The block diagram of the scanning-type measuring device of this invention. The graph example of the data measured using the dynamic range expansion method of the sensor which concerns on Example 2 of this invention. The flowchart which shows the measuring method in the conventional scanning type measuring device.

Explanation of symbols

1 Sensor 2 Sensor Output Reset Circuit 3 A / D Converter 4 CPU
5 Scanning stage 6 Sample 10 Signal 11 generated from sample 11 Signal detected by sensor with measurement method according to the present invention 12 Upper limit of sensor measurement range 13 Preset value 14 for resetting sensor Before resetting sensor output Measured data 15 Measured data after resetting sensor output

Claims (8)

  In a measurement method of a scanning measurement apparatus that scans a sample with respect to a sensor and measures a signal generated from the sample using the sensor, resetting the output of the sensor after measuring the signal at each measurement position; A method for expanding a dynamic range of a sensor, comprising: adding a difference between an output value of the sensor after resetting and measurement data before resetting as an offset value to measurement data at a next measurement position.   2. The sensor output is reset only when measurement data at each measurement position exceeds a preset range between a value when the sensor is reset and a value when the sensor is saturated. A method for expanding the dynamic range of the described sensor.   3. The sensor dynamic range expansion method according to claim 1, wherein the sensor is a magnetic sensor.   The sensor dynamic range expansion method according to claim 1, wherein the sensor is a superconducting quantum interference device. A scanning stage for scanning a sample, a sensor for measuring a signal generated from the sample, an A / D converter for converting the output of the sensor into digital data, and the digital data from the A / D converter In a scanning type measuring device comprising a CPU for collecting measurement data as a measurement data and a memory for storing the measurement data collected by the CPU,
A sensor output reset circuit for resetting the output of the sensor is provided,
After measuring the signal at each measurement position, reset the output of the sensor, and add the difference between the output value of the sensor after reset and the measurement data before reset to the measurement data at the next measurement position as an offset value. A scanning type measuring device.   6. The sensor output is reset only when measurement data at each measurement position exceeds a preset range between a value when the sensor is reset and a value when the sensor is saturated. The scanning type measuring apparatus described.   The scanning measurement apparatus according to claim 5 or 6, wherein the sensor is a magnetic sensor.   The scanning measurement apparatus according to claim 5, wherein the sensor is a superconducting quantum interference device.

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