JPH1138338A - Sampling signal generator and scanning optical microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide digital image data without distortion from which the influence of change of a scanning frequency is removed, by generating a sampling signal utilized at the time of digitizing an object image signal irradiated with scanning light as one exactly following up the scanning frequency. SOLUTION: When a mirror of a resonant galvano scanner 14 is moved for deflecting a laser beam from a laser beam source 10 and scanning it on a sample 12, the moving speed is detected by a speed sensor 16 and the detected signal is sent to a frequency measuring part 17 and a comparator 21. In the comparator 21, the detected signal is compared with a preset reference voltage and a pulse signal as a coincident detection signal to CPU 18. In CPU 18, a sampling signal having the frequency corresponding to the scanning frequency measured in the frequency measuring part 17 is calculated according to an arithmetic expression. In a delay circuit 20, after delaying the sampling signal from CPU 18 by a prescribed time, it is sent to a A/D converter 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for, for example, a laser printer or a bar code reader, and deflects light from a light source to scan an object. The present invention relates to a sampling signal generator for generating a sampling signal for digitizing an image signal and a scanning optical microscope using the same.

[0002]

2. Description of the Related Art As is well known, a scanning microscope optically scans a sample, makes reflected light from the sample by the scanning light incident on a photodetector, and obtains an image signal by photoelectrically converting the light. A digital image signal is converted as a signal using the sampling signal of the obtained image signal as a trigger.

Conventionally, optical scanning with this type of scanning microscope includes a galvanometer mirror that performs reciprocating motion as a linear motion and a polygon mirror that performs a rotary motion. Some use a resonant scanner such as a resonant scanner that performs nonlinear motion.

However, in a galvanomirror or a polygon mirror that performs a linear motion, sampling signals generated to obtain a linear image may have equal time intervals.
On the other hand, when using a resonant scanner that performs nonlinear motion, the time intervals of the sampling signals are made unequal in order to obtain a linear image.

FIG. 6 exemplifies the timing of generation of a sample signal sequence in a spot movement waveform using the above-described resonant scanner. The time interval is set so that the interval of the x axis of the spot movement waveform is constant as shown in the figure. It can be seen that an uneven sampling signal must be generated.

As another example of performing optical scanning, as shown in Japanese Patent Application Laid-Open No. Hei 7-159711, the frequency of a drive signal of a resonance scanner is changed so as to stabilize the amplitude of the resonance scanner to the maximum. There is something.

[0007]

However, in the above-mentioned scanning optical microscope, although the resonance scanner to be used is manufactured with great care in order to eliminate individual differences and to align resonance frequencies, Since the resonance frequency changes due to factors such as the environmental temperature, a sampling signal having a frequency adapted to the changed resonance frequency of the resonance scanner is required to obtain a linear image.

For example, when a galvano scanner having a resonance frequency of 4 [kHz] is used, when the frequency becomes 4.04 [kHz] due to a temperature change, an analog signal is used using a sampling signal of 4 [kHz]. Is sampled to obtain digital-value image data, the left and right portions in the obtained image data have a total ratio of 5%.
% Of distortion will occur.

Further, as described above, Japanese Patent Application Laid-Open No.
In Japanese Patent Laid-Open No. 11 (1999), the frequency of the drive signal is changed in order to stabilize the amplitude of the resonant scanner to the maximum, but the frequency of the drive signal must be constantly changed in order to execute such control. This causes a variation in the resonance frequency, which makes it impossible to obtain digital value image data with good linearity.

Further, as described above, the resonance scanner is manufactured so as to minimize the individual difference at the time of its manufacture and to make the resonance frequency uniform. However, it is difficult to completely eliminate the individual difference. When a sampling signal of a frequency created based on the design resonance frequency is used, a deviation occurs between the actual resonance frequency and the sampling signal, and the obtained image data is also distorted.

In order to eliminate individual differences in the resonance frequency of the resonance scanner, it is also conceivable to measure the resonance frequency of each individual in advance and match the sampling signal to the measured resonance frequency. The assembly cost of the entire microscope apparatus is increased, which is not practical.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to change the scanning frequency of a scanner that deflects light from a light source to generate scanning light on an irradiation target. Or, even if the scanning frequency differs from the design value due to individual differences of the scanner, the sampling signal used when digitizing the image signal of the target is assumed to exactly follow the scanning frequency at that time. An object of the present invention is to provide a sampling signal generating device capable of generating a signal and a scanning optical microscope using the device.

[0013]

According to the first aspect of the present invention,
Deflecting means for deflecting light from the light source and repeatedly scanning,
Detecting means for detecting the scanning speed of the deflecting means; frequency measuring means for measuring the scanning frequency of the deflecting means based on the detection result of the detecting means; and a detection result of the detecting means and a preset reference value. A comparison means for performing a match comparison;
Calculating means for calculating a sampling signal and a delay time corresponding to the scanning timing of the deflecting means based on a scanning frequency of the deflecting means measured by the frequency measuring means and a comparison result of the comparing means; and a sampling signal from the calculating means. And a delay means for delaying and outputting the calculated delay time by the calculated delay time.

As a result of such a configuration, even if the scanning frequency of the deflecting means (scanner) changes, or the scanning frequency differs from the design value due to individual differences, the image of the object to be irradiated with the scanning light is obtained. A sampling signal used when digitizing a signal can be generated as exactly following the scanning frequency at that time, and as a result, distortion-free digital image data that eliminates the influence of the above scanning frequency change Can be obtained.

According to a second aspect of the present invention, there is provided a deflecting means for deflecting light from a light source to repeatedly scan, a detecting means for detecting a scanning speed of the deflecting means, and a detecting means for detecting the scanning speed of the deflecting means. Frequency measuring means for measuring a scanning frequency, comparing means for matching and comparing a detection result of the detecting means with a preset reference value, storing means for storing sampling signals of a plurality of cycles in advance, and Control means for reading out and outputting a sampling signal having a cycle corresponding to the scanning timing of said deflecting means from said storage means based on a scanning frequency of said deflecting means measured by said means and a comparison result of said comparing means. And

As a result of this configuration, even if the scanning frequency of the deflecting means (scanner) changes, or the scanning frequency differs from the design value due to individual differences, the image of the object to be irradiated with the scanning light is obtained. A sampling signal used when digitizing a signal can be generated as exactly following the scanning frequency at that time, and as a result, distortion-free digital image data that eliminates the influence of the above scanning frequency change In addition to the above, it is possible to reduce the load required for calculation processing and the like because the sampling signal stored in advance is read and output at an appropriate cycle from among the stored sampling signals. Even so, a sampling signal can be reliably generated in response to this.

According to a third aspect of the present invention, there is provided a deflecting means for deflecting light from a light source to repeatedly scan an observation sample, and converting the brightness of transmitted light or reflected light of the observation sample scanned by the deflecting means into analog data. Light detecting means for detecting a value signal, speed detecting means for detecting a scanning speed of the deflecting means, frequency measuring means for measuring a scanning frequency of the deflecting means based on a detection result of the speed detecting means, and detecting means Comparing means for comparing the detection result of the detection means with a preset reference value, and corresponding to the scanning timing of the deflection means based on the scanning frequency of the deflection means measured by the frequency measurement means and the comparison result of the comparison means. Sampling signal generating means for generating a sampling signal generated by the detecting means, and the light detecting means using the sampling signal generated by the sampling signal generating means. The output luminance signal of the analog value of the characterized by comprising a conversion means for converting into a digital value.

As a result of this configuration, even if the scanning frequency of the deflecting means (scanner) changes or the scanning frequency differs from the design value due to individual differences, the image signal of the observation sample is digitized. The sampling signal used at the time can be generated as exactly following the scanning frequency at that time, and as a result, it is possible to obtain distortion-free digital image data excluding the influence of the change in the scanning frequency. Can be.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) A first embodiment in which the present invention is applied to a scanning optical microscope will be described below with reference to the drawings.

FIG. 1 shows a part of the schematic structure.
Reference numeral 10 denotes a laser light source. The laser light from the laser light source 10 is reflected by a mirror attached to the resonance galvano scanner 14, is condensed in a spot shape by the objective lens 11, and then irradiates the observation sample 12.

At this time, the laser beam scans the observation sample 12 by the resonance galvano scanner 14 driven and controlled by the scanner driving section 15, and the laser beam transmitted through the observation sample 12 is a light constituted by, for example, a CCD or the like. The image signal is detected by the detector 13 as an image signal having an analog value corresponding to the luminance, and is sent to an A / D converter 19 described later.

On the other hand, the mirror of the resonance galvano scanner 14 deflects the laser beam from the laser
When moving to scan on the second, the speed sensor 16 detects the moving speed, and the detection signal is
7 and the comparator 21.

The frequency measuring unit 17 generates a frequency signal corresponding to the moving speed of the mirror from the period of the amplitude of the detection signal corresponding to the moving speed of the mirror of the resonant galvano scanner 14 given from the speed sensor 16, Output to CPU18.

Further, in the comparator 21 to which the detection signal from the speed sensor 16 is given, the detection signal from the speed sensor 16 is used as a + (plus) input, and a preset reference voltage is used as a-(minus) terminal input. Are compared with each other, and a pulse signal is output to the CPU 18 as a coincidence detection when the two coincide with each other, that is, when the subtraction becomes "0 (zero)".

In the CPU 18, according to an arithmetic expression described later,
A sampling signal having a frequency corresponding to the scanning of the mirror is calculated from the scanning frequency measured by the frequency measuring unit 17, and at the same time, a delay time Δt is calculated to synchronize the sampling signal with the scanning timing of the mirror. The obtained sampling signal and the delay time Δt are provided to the delay circuit 20.

In the delay circuit 20, the sampling signal supplied from the CPU 18 is transmitted to the A / D converter 19 after being delayed by the same delay time .DELTA.t. The image signal of the analog value from the detector 13 is digitized to a preset quantization bit number, and is output as digital image data to a subsequent image processing circuit (not shown) including an image memory.

Next, the relationship between the movement of the spot of the laser beam scanned on the observation sample 12 and the detection output of the speed sensor 16 will be described. Since the resonant galvano scanner 14 resonates the mirror, the detection output v of the speed sensor 16 is given by the following equation: v = Asin (2πft + δ1) (1) (where A: amplitude, f: frequency, t: time, δ1: Phase).

The movement x of the spot of the laser beam on the observation sample 12 can be expressed by the following equation: x = Bcos (2πft + δ2) (2) (where B: amplitude, δ2: phase).

Next, a sampling signal for generating digital image data having good linearity will be described.
In order to obtain linear digital image data from a spot of laser light moving in a cosine waveform, the interval between sampling signals must be changed so that the difference between the current sampling position and the next sampling position is constant. No. Therefore, assuming that the number of samples is N and the effective sampling range is B 'as shown in FIG.
0th, 1st, 2nd, ‥‥, i-th position x0, x
1, x2, ‥‥, xi are given by: x0 = B 'x1 = B'-B' / (N / 2) * 1 x2 = B'-B '/ (N / 2) * 2:: xi = B ( 1- (2i / N)) (3)

Further, when xi is expressed using the above equation (2), the phase is set to "0" for simplicity assuming that it is practically negligible, and xi = Bcos (2πfti) (4).

When ti is obtained from the above equations (3) and (4), ti = (1 / 2πf) cos ^-1 ((B '/ B) (1- (2i / N))) (5) ).

The CPU 18 calculates t for the number of samplings N based on the equation (5) and outputs it to the delay circuit 20 as a sampling signal sequence. FIG. 2 shows the CP
U18 exemplifies a sampling signal sequence obtained by calculation, for example, when the measured scanning frequency is 4 [kHz].
, The sampling signal sequence 1 shown in the figure is output. Similarly, if the sampling signal sequence is 4.04 [kHz], the sampling signal sequence 2 is changed to 3.96 [kHz]. 3 are output.

At this time, the CPU 18 simultaneously determines the delay time Δ
Calculate t. FIG. 3 illustrates a calculation method at this time. The delay time Δt is equal to the detection output v = 0 of the speed sensor 16.
It is the time from the timing when the timing becomes to the timing t0. In order to simplify the operation, the voltage at the time when the detection output v of the speed sensor 16 becomes 0 is set in advance as a reference voltage in the comparator 21, and after the coincidence signal is input from the comparator 21, the CPU 18 The delay time Δt and the sampling signal sequence as shown in FIG.

The delay circuit 20 sends a sampling signal sequence sent after a lapse of the sent delay time Δt to the A / D converter 19, and the A / D converter 19 The image signal of the analog value from the photodetector 13 is digitized based on a predetermined number of quantization bits by using the column as a trigger signal, and is output as digital image data to a subsequent image processing circuit.

As described above, even if the scanning frequency of the resonant galvano scanner 14 changes due to an external environment or the scanning frequency differs from the design value due to the individual difference in the first place, the image of the photodetector 13 can be changed. A sampling signal used for digitizing the signal is calculated by the CPU 18, generated as a signal that accurately follows the actual scanning frequency at that time via the delay circuit 20, and given to the A / D converter 19. Therefore, the A / D converter 19 can obtain digital image data without distortion by eliminating the influence of the change in the scanning frequency as described above.

(Second Embodiment) Next, a second embodiment in which the present invention is applied to a scanning optical microscope will be described with reference to the drawings.

FIG. 5 shows a part of the schematic structure.
Basically, it is almost the same as FIG. 1 described above, and therefore, the same portions are denoted by the same reference numerals and description thereof will be omitted. The CPU 18 ', to which the scanning frequency measured by the frequency measuring unit 17 and the comparison result of the comparator 21 are input, is provided to the CPU 18' based on the design value of the scanning period of the resonant galvano scanner 14 in accordance with the scanning frequency. PROM2 in which the sampling signals of
2 are connected.

The CPU 18 ′ reads a sampling signal of a corresponding cycle from the PROM 22 based on the scanning frequency measured by the frequency measuring unit 17, and reads the read sampling signal at the timing when the coincidence signal from the comparator 21 is input. At the same time, the operation of directly outputting to the A / D converter 19 is repeatedly executed.

As described above, since a sampling signal having an appropriate cycle is read out from the sampling signal stored in the PROM 22 and output, the load required for the calculation processing in the CPU 18 is greatly reduced, and the processing speed is increased. can do. Thereby, for example, the resonance frequency becomes more than 10 [kHz]
Even when a resonant galvano scanner or the like that performs high-speed scanning of about z] is used, a sampling signal can be reliably generated in response to this. In this case, the scanning frequencies 4 [kHz] and 10 [k] are stored in the PROM 22.
[Hz], or may be replaced with a PROM 22 to which data corresponding to 10 [kHz] has been input.

As in the case of the first embodiment, the scanning frequency of the resonant galvano scanner 14 varies depending on the external environment, or the scanning frequency differs from the design value due to individual differences in the first place. A / D converter 1
In No. 9, it is of course possible to obtain digital image data without distortion by eliminating the influence of such a change in the scanning frequency.

Note that the first and second embodiments have the following features.
In both cases, the present invention is applied to a scanning optical microscope.However, the present invention is not limited to this.For example, a laser printer, a bar code reader, or the like deflects light from a light source to scan an object and scans an image signal. It is needless to say that any method can be applied as long as it generates a sampling signal when A / D conversion is performed. In addition, the present invention can be variously modified and implemented without departing from the gist thereof.

[0042]

According to the first aspect of the present invention, even if the scanning frequency of the deflecting means (scanner) changes or the scanning frequency differs from the design value due to individual differences,
The sampling signal used when digitizing the image signal of the object to be irradiated with the scanning light can be generated as exactly following the scanning frequency at that time. As a result, the influence of the change in the scanning frequency can be obtained. And digital image data without distortion can be obtained.

According to the second aspect of the present invention, even if the scanning frequency of the deflecting means (scanner) changes or the scanning frequency differs from the design value due to individual differences,
The sampling signal used when digitizing the image signal of the object to be irradiated with the scanning light can be generated as exactly following the scanning frequency at that time. As a result, the influence of the change in the scanning frequency can be obtained. And digital image data without distortion can be obtained.
Since a signal having an appropriate period is read out and output from the sampling signals stored in advance, it is possible to reduce a load required for a calculation process and the like. A sampling signal can be reliably generated.

According to the third aspect of the present invention, even if the scanning frequency of the deflecting means (scanner) changes or the scanning frequency differs from the design value due to individual differences,
The sampling signal used when digitizing the image signal of the observation sample can be generated as exactly following the scanning frequency at that time, and as a result, distortion that eliminates the influence of the scanning frequency change is eliminated. Without digital image data.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining an operation according to the embodiment;

FIG. 3 is a diagram illustrating an operation according to the embodiment.

FIG. 4 is a diagram for explaining an operation according to the embodiment;

FIG. 5 is a diagram showing a schematic configuration according to a second embodiment of the present invention.

FIG. 6 is a diagram exemplifying a sampling signal sequence generated with nonlinear movement of a resonance scanner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Laser light source 11 ... Objective lens 12 ... Observation sample 13 ... Photodetector 14 ... Resonant galvano scanner 15 ... Scanner drive part 16 ... Speed sensor 17 ... Frequency measurement part 18 ... CPU 19 ... A / D converter 20 ... Delay circuit 21: Comparator 22: PROM

Claims (3)

[Claims] 1. A deflecting means for deflecting light from a light source to scan repeatedly, a detecting means for detecting a scanning speed of the deflecting means, and a frequency for measuring a scanning frequency of the deflecting means based on a detection result of the detecting means. Measuring means, comparing means for comparing the detection result of the detecting means with a preset reference value, and comparing the scanning frequency of the deflecting means measured by the frequency measuring means with the comparison result of the comparing means. A calculating means for calculating a sampling signal and a delay time corresponding to the scanning timing of the deflecting means; and a delay means for delaying and outputting the sampling signal from the calculating means by the calculated delay time. Sampling signal generator. 2. A deflecting means for deflecting light from a light source to scan repeatedly, a detecting means for detecting a scanning speed of the deflecting means, and a frequency for measuring a scanning frequency of the deflecting means based on a detection result of the detecting means. Measuring means; comparing means for comparing the detection result of the detecting means with a preset reference value; storing means for storing sampling signals of a plurality of cycles in advance; and the deflection measured by the frequency measuring means. Control means for reading out and outputting a sampling signal having a cycle corresponding to the scanning timing of said deflecting means from said storage means based on a scanning frequency of said means and a comparison result of said comparing means. apparatus. 3. A deflecting means for deflecting light from a light source to repeatedly scan an observation sample, and detecting the luminance of transmitted light or reflected light of the observation sample scanned by the deflecting means as an analog signal. Light detecting means; speed detecting means for detecting the scanning speed of the deflecting means; frequency measuring means for measuring the scanning frequency of the deflecting means based on the detection result of the speed detecting means; A comparison unit that matches and compares the reference value with the reference value, and a sampling signal corresponding to the scanning timing of the deflection unit is generated based on the scanning frequency of the deflection unit measured by the frequency measurement unit and the comparison result of the comparison unit. A sampling signal generating means, and an analog output from the light detecting means with the sampling signal generated by the sampling signal generating means. A conversion means for converting a luminance signal of a digital value into a digital value.