JPH085332A - Signal processor having noise decreasing function - Google Patents

Abstract

PURPOSE:To speed up the opening and closing of a shutter, and to remove the noise component, which is fluctuated during scanning. CONSTITUTION:The transmitted light or the reflected light through a sample S illuminated with the light emitted from a light source part 1 is converted into the photoelectric converted signal with a photoelectric conversion part 3, the photoelectric converted signal is converted into the digital data with an A/D converting part 5 in synchronization with an A/D conversion clock and the noise component is removed from the digital data. A shutter 20 is arranged on the optical path from the light source part 1 to the sample S. A shutter control means 21 accepts the A/D conversion clock and controls the opening and closing of the shutter 20 in synchronization with the clock. A noise removing means 22 subtracts the digital data when the shutter 20 is closed from the digital data when the shutter 20 is opened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal processing circuit for removing noise in a scanning optical microscope or the like, and more particularly to a noise reducing function for removing noise in a signal path or noise due to ambient light from sample image data. The present invention relates to a signal processing device provided.

[0002]

2. Description of the Related Art A scanning microscope is known as an apparatus for scanning a sample with a laser beam and imaging a sample image in synchronization with the scanning. Generally, a scanning microscope converts transmitted light or reflected light of a laser-scanned sample into a photoelectric conversion signal by a photoelectric converter such as a photomultiplier tube or a photodiode, and converts the photoelectric conversion signal into an A / D conversion circuit. A signal processing circuit for storing in a memory after being quantized by. A signal processing circuit of this type is considered to be provided with a noise reduction circuit for removing system noise contained in the photoelectric conversion signal, and is disclosed in Japanese Patent Laid-Open No. 30635/1988.

FIG. 6 shows an example of the configuration of a conventional signal processing device with a noise reduction function. This signal processing device includes a light source 1
The mechanical shutter 2 is arranged on the optical path for guiding the light emitted from the sample S to the sample S, and the transmitted light transmitted through the sample S is converted into a photoelectric conversion signal by the photoelectric conversion unit 3. The photoelectric conversion signal is amplified by the amplifier 4 and then input to the A / D converter 5, and is quantized in synchronization with the A / D conversion clock generated from the clock generation circuit 6. The memory control circuit 7 sends this digital data to A
The data is recorded in the memory 8 in synchronization with the / D conversion clock. A shutter opening / closing circuit 9 which receives an opening / closing command from the CPU 10 opens / closes the mechanical shutter 2.

In the signal processing apparatus described above, the CPU 10 sends a close command to the shutter opening / closing control circuit 9 before or after the scanning is completed, and the memory control circuit 7 is operated.
To the A / D conversion output write command. As a result, the mechanical shutter 2 is closed and the photoelectric conversion unit 3 is closed.
Only ambient light is incident on the memory 8, and the photoelectric conversion units 3, 3 enter the memory 8.
The electrical noise generated in the amplifier 4 and the A / D converter 5 and the noise caused by the ambient light incident on the photoelectric conversion unit 3 are stored. Hereinafter, the data recorded when the shutter is closed (consisting of only noise) is D1.

Next, the CPU 10 sends an open command to the shutter opening / closing control circuit 9 and a write command of the A / D conversion output to the memory control circuit 7. As a result, the mechanical shutter 2 is opened, and the ambient light and the transmitted light of the sample S enter the photoelectric conversion unit 3. Therefore,
The image data of the sample S containing the noise is stored in the memory 8. Hereinafter, the data recorded when the shutter is open will be referred to as D2. The CPU 10 reads the data D1 and D2 from the memory 8 and subtracts D1 from D2 to obtain noise-free data.

[0006]

However, the above-described signal processing device with a noise reduction function is designed on the premise that the noise data D1 is taken in immediately before or immediately after the start of scanning, and therefore, during the scanning period. There is a problem that the fluctuating noise component cannot be removed. In order to remove the noise component that fluctuates during the scanning period, the noise data D
1 must be captured in a short cycle even during the scanning period. However, the CPU 10 confirms the opening / closing of the shutter by a signal from the opening / closing detection sensor, and the CPU 10 opens / closes the shutter opening / closing control circuit 9 based on the timing output of the timer.
It was difficult to increase the shutter opening / closing speed in the system configuration that gives the opening / closing command to the shutter because of the reaction time of the sensor and the set time of the timer.

The present invention has been made in view of the above circumstances, and it is possible to increase the opening / closing speed of the shutter, remove noise components that fluctuate during scanning, and reduce noise with a high noise reduction effect. An object is to provide a signal processing device with a function.

[0008]

The present invention has taken the following means in order to achieve the above object. According to the present invention corresponding to claim 1, transmitted light or reflected light of a sample irradiated with light incident from a light source unit is converted into a photoelectric conversion signal by a photoelectric conversion unit, and the photoelectric conversion signal is converted into an A / D conversion unit by A / D conversion unit. In a signal processing device with a noise reduction function for converting digital data in synchronism with a / D conversion clock and removing a noise component from the digital data, a shutter arranged on an optical path from the light source unit to the sample, A shutter control means for inputting and receiving the same clock as the A / D conversion clock and controlling opening and closing of the shutter in synchronization with the clock; and digital data obtained when the shutter is in the open state, obtained when the shutter is in the closed state. And a noise removing means for subtracting the obtained digital data.

[0009]

The present invention has the following effects by taking the above measures. According to the present invention corresponding to claim 1, the same clock as the A / D conversion clock for quantizing the photoelectric conversion signal is input to the shutter control means, and the opening and closing of the shutter is controlled in synchronization with the clock. A / D
The photoelectric conversion signals when the shutter is closed and when the shutter is opened are converted into digital data by the A / D conversion unit in synchronization with the conversion clock. The digital data converted by the A / D converter is input to the noise removing means. The noise removing means subtracts the digital data obtained when the shutter is closed from the digital data obtained when the shutter is open to obtain noise-free digital data. Therefore, since the A / D conversion clock is directly input to the shutter control means as the opening / closing instruction, the shutter opening / closing speed can be increased as compared with the case where the CPU intervenes to issue the opening / closing instruction.

[0010]

Embodiments of the present invention will be described below. FIG. 1 is a diagram showing the configuration of a signal processing device with a noise reduction function, in which the present invention is applied to a scanning laser microscope. The same parts as those of the signal processing device shown in FIG. 6 described above are designated by the same reference numerals.

In the signal processing apparatus of this embodiment, a shutter 20 is arranged on the optical path for guiding the light emitted from the light source 1 to the sample S, and the shutter 20 is opened / closed by a shutter opening / closing control circuit 21. The shutter opening / closing control circuit 21 is connected to the clock generation circuit 6, and the clock generation circuit 6 outputs
The / D conversion clock is directly input as a shutter opening / closing command. The CPU 22 via the internal bus 11 to the clock generation circuit 6, the memory control circuit 7, and the shutter opening / closing control circuit 21.
Are connected. It is assumed that the CPU 22 sets predetermined settings for those connected components and gives timing signals such as operation start, interruption, and end based on a control program stored in advance. Also, CPU2
Reference numeral 2 has a function as a noise removing means for removing noise from the digital data recorded in the memory 8.

Next, the operation of this embodiment configured as described above will be described with reference to the time chart of FIG. A generated by the clock generation circuit 6 as shown in FIG.
The / D conversion clock is input to the A / D converter 5 and the memory control circuit 7, and also to the shutter opening / closing control circuit 9. As shown in FIG. 2B, the shutter opening / closing control circuit 9 is driven so that the shutter 20 is opened at the first rising edge thereof in synchronization with the A / D conversion clock, and at the next rising edge of the same clock. The shutter 20 is driven so as to be in a closed state. Thereafter, similarly, the open / close drive is repeated in synchronization with the rising edge of the A / D conversion clock.

When the shutter 20 is in the open state, the light path is opened, so that the light from the light source 1 passes through the shutter 20 and is applied to the sample S. The light transmitted through the sample S is converted into a photoelectric conversion signal by the photoelectric conversion unit 3 and amplified by the amplifier 4,
Input to the A / D converter 5. The A / D converter 5 operates with the same clock generated by the clock generation circuit 6 and converts the photoelectric conversion signal into digital data. The writing of this digital data into the memory 8 is controlled by the memory control circuit 7. That is, as shown in FIG. 2C, it is stored in the memory 8 in synchronization with the fall of the A / D conversion clock during the shutter opening period and the shutter closing period. As a result, the data D when the shutter 2 is open is stored in the memory 8.
_n , D _{n + 2} , D _{n + 4} and data D _{n + 1} , D _{n + 3} , D _{n + 5} when the shutter 2 is closed are stored. The data D _n , D _{n + 2} , and D _{n + 4} when the shutter 2 is in the open state are converted into a photoelectric conversion signal of transmitted light that does not include noise due to ambient light, the photoelectric conversion unit 3, the amplifier 4, and the A / D conversion. The data includes electrical noise of the device 5 and noise due to ambient light received by the photoelectric conversion unit 3. The data D _{n + 1} , D _{n + 3} , D _{n + 5} when the shutter 2 is closed are the electrical noise of the photoelectric conversion unit 3, the amplifier 4 and the A / D converter 5 and the photoelectric conversion unit 3.
The data consists of noise due to the ambient light received at.

The CPU 22 reads the data in the shutter open state and the data in the shutter closed state thus stored in the memory 8 and subtracts the data in the next shutter closed state from the data in the shutter open state. . _{That, (D n -D n + 1} ), (D n + 2 -D n + 3), (D
_{n + 4−} D _{n + 5} ) ... The calculation result is stored in the memory 8 as noise-free data.

The CPU 22 reads the data from the memory 8 and performs the above subtraction processing either when one line scanning is completed or one frame scanning is completed after the shutter is opened and closed once. .

As described above, according to this embodiment, the A / D conversion clock generated from the clock generation circuit 6 is input to the shutter opening / closing control circuit 21 as an opening / closing command, and the shutter is opened from the data in the state where the shutter is opened. Since the data in the closed state is subtracted, the shutter 20 can be opened and closed at the same speed as the A / D conversion cycle of the photoelectric conversion signal, and even if the noise component varies during the scanning period. It is possible to obtain data in which the noise component is sufficiently removed.

In the above embodiment, the opening and closing of the shutter 20 is toggled. However, the opening and closing of the shutter 20 need only be driven in synchronization with the A / D conversion, and it is not always necessary to toggle the opening and closing of the shutter.

Further, in the above embodiment, the noise removing means is realized by using the arithmetic function of the CPU 22, but a similar subtracting function can be realized by a hardware circuit. FIG.
Shows an embodiment in which the shutter in the above embodiment is composed of a stepping motor and a comb-shaped disk. In the figure, the same parts as those in the embodiment shown in FIG. 1 described above are designated by the same reference numerals.

In this embodiment, a stepping motor 23 is provided in the vicinity of the optical path between the light source 1 and the sample S, and the central axis of the comb-shaped disk 24 is fixed to the rotation axis of the stepping motor 23 so that the disk 24 is comb-shaped. The tooth-shaped outer periphery blocks the optical path. A / D generated by the clock generation circuit 6 in the motor drive circuit 25 that drives the stepping motor 23
Input the conversion clock. Motor drive circuit 25 is A / D
The comb-shaped disk 24 is rotated in synchronization with the conversion clock.
In the comb-toothed disk 24, comb teeth having a constant width are formed on the outer circumference of the disk at regular intervals.

In this embodiment, the motor drive circuit 25 has an A
When the D / D conversion clock is input, the motor drive circuit 25 receives the stepping motor 23 based on the clock pulse.
Drive. Therefore, when the comb-teeth disk 24 rotates in synchronization with the A / D conversion clock, the comb teeth of the rotating comb-teeth disk 24 block the incident light at a constant cycle, and the comb-teeth disk 24 of the comb-teeth disk 24 rotates. The light passing between the comb teeth is incident on the sample S. By opening / closing such an optical path, the sample S
Is irradiated with light that blinks in synchronization with the A / D conversion clock, and the transmitted light is converted into photoelectric conversion signals one after another by the photoelectric conversion unit 3. Further, the photoelectric conversion signal is stored in the memory 8 via the amplifier 4 and the A / D converter 5. CPU22,
The A / D conversion data when the optical path is opened and when the optical path is blocked is read from the memory 8 and noise is removed from the photoelectric conversion signal by the above-described subtraction processing.

FIG. 5 shows an embodiment in which the shutter in the above embodiment is composed of a servo motor, a comb-shaped disk, a rotation sensor, a phase comparator and the like. Note that FIG.
The same parts as those in the embodiment shown in FIG.

In this embodiment, a servo motor 26 is provided near the optical path between the light source 1 and the sample S, and the servo motor 26 is provided.
The central axis of the comb-shaped disk 27 is fixed to the rotation axis of the. The rotation of the comb-shaped disk 27 is detected by the rotation sensor 28, converted into a rotation detection signal, and input to the phase comparator 29. Phase comparator 2
Reference numeral 9 compares the A / D conversion clock generated from the clock generation circuit 6 with the rotation detection signal, and inputs a control signal (deviation) for synchronizing with the rotation detection signal to the motor drive circuit 30.
The motor drive circuit 30 drives the servo motor 26 based on the control signal. The comb-toothed disc 24 has comb teeth having a constant width formed on the outer periphery of the disc at regular intervals, and is fixed to the rotation shaft of the servomotor 26 so that the outer periphery of the disc blocks the optical path.

In this embodiment, the servo motor 26 is driven by the motor drive circuit 30 which receives a drive command from the CPU 22.
Is driven to rotate the comb-toothed disk 27. Comb-shaped disk 27
With the rotation of, the optical path is repeatedly opened and closed. On the other hand, the phase comparator 29 uses the A / D from the clock generation circuit 6.
The conversion clock is input, and the rotation detection signal corresponding to the rotation of the comb-shaped disk 27 is input from the rotation sensor 28. Since the rotation detection signal represents the repetition cycle of opening and closing of the optical path, whether the opening and closing of the optical path is synchronized with the A / D conversion operation by comparing this rotation detection signal with the A / D conversion clock. You can judge whether or not. If the two are not synchronized, the motor drive circuit 30 which receives the control signal from the phase comparator 29 according to the synchronization deviation is the servo motor 26.
Control the rotation speed of. The noise components are removed from the data stored in the memory 8 when the optical path is opened and when the optical path is blocked, as in the above-described embodiments.

As described above, according to this embodiment, the optical path can be opened and closed at high speed, and the optical path opening / closing operation and the A / D conversion operation can always be reliably synchronized. FIG. 5 shows an embodiment of a scanning laser microscope which photoelectrically converts the reflected light of the sample S and stores it. In the figure, the same parts as those of the signal processing apparatus shown in FIG. 1 described above are designated by the same reference numerals.

In this embodiment, the shutter 20 and the sample S
The beam splitter 40 is arranged on the optical path between the two, and the reflected light of the sample S is reflected by the beam splitter 40 and is incident on the photoelectric conversion unit 3.

According to this embodiment, it can be applied to a reflection type scanning laser microscope. In each of the above-described embodiments, the high-speed mechanical shutter that rotates the comb-shaped disk by the stepping motor and the servo motor is used, but a liquid crystal shutter and AOM can also be used. The present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention.

[0027]

As described above in detail, according to the present invention, it is possible to increase the opening / closing speed of the shutter, remove the noise component fluctuating during scanning, and obtain a signal with a noise reducing function having a high noise reducing effect. A processing device can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a signal processing device in which the present invention is applied to a scanning microscope.

FIG. 2 is a time chart for explaining the operation of the signal processing device shown in FIG.

FIG. 3 is a configuration diagram of another embodiment in which a stepping motor and a comb-shaped disc are used for a high-speed shutter.

[Fig. 4] High-speed shutter, servo motor, comb-shaped disk,
It is a block diagram of another embodiment using a phase comparator.

FIG. 5 is a configuration diagram of an embodiment of a signal processing device in which the present invention is applied to a reflective scanning laser microscope.

FIG. 6 is a block diagram of a conventional signal processing device with a noise reduction function.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light source, 3 ... Photoelectric conversion part, 4 ... Amplifier, 5 ... A / D converter, 6 ... Clock generation circuit, 7 ... Memory control circuit, 8
... memory, 11 ... internal bus, 20 ... high-speed mechanical shutter, 21 ... shutter opening / closing control circuit, 23 ... stepping motor, 24 ... comb-shaped disc, 25 ... motor drive circuit.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area H04N 7/18 C

Claims (1)

[Claims] 1. A photoelectric conversion unit converts the transmitted light or reflected light of a sample irradiated with light incident from a light source unit into a photoelectric conversion signal, and the photoelectric conversion signal is converted into an A / D conversion clock in the A / D conversion unit. A signal processing device with a noise reduction function for synchronously converting to digital data and removing a noise component from the digital data, comprising: a shutter arranged on an optical path from the light source unit to the sample; and the A / D conversion. The same clock as the clock is input, shutter control means for opening and closing the shutter in synchronization with the clock, and digital data obtained when the shutter is closed from digital data obtained when the shutter is open A signal processing device with a noise reducing function, comprising: a noise removing means for subtracting.