JP2018081136A - Optical scanner and image synchronization signal adjustment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct deviation of sampling timing.SOLUTION: A scanning microscope 100 includes: a scanner 4a for moving a light focusing position of illumination light radiated to a sample S; an optical detector 13 for detecting light from the sample S to which the illumination light is radiated; and an image synchronization signal generation circuit 19 for generating an image synchronization signal to limit timing for sampling an analog signal output from the optical detector 13 on the basis of a scanning synchronization signal indicating scan timing of the scanner 4a. The image synchronization signal generation circuit 19 includes a phase-shift circuit 54a for shifting a phase of the image synchronization signal according to an amount of phase-shift, i.e. an amount of the phase determined based on a scan frequency of the scanner 4a.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an optical scanning device and an image synchronization signal adjustment method.

  In an optical scanning device such as a scanning microscope, a sampling clock indicating the timing for sampling an image signal is generated based on a scanning synchronization signal output from a scanner. However, the timing of sampling according to the sampling clock may deviate from the timing at which the light traveling on the sample is at a desired position due to various factors.

  It is known that such timing deviation (hereinafter referred to as timing deviation or sampling timing deviation) causes image distortion, positional deviation, and the like. A technique related to this problem is described in Patent Document 1, for example. Patent Document 1 describes a technique that corrects both a deviation caused by a difference between a reference temperature and a temperature of an actual use environment and a deviation caused by an individual difference between apparatuses.

JP 2011-123142 A

  By using the technique described in Patent Document 1, it is possible to correct timing deviations caused by temperature and timing deviations caused by individual differences between apparatuses. However, the sampling timing shift is not only caused by these, but can also be caused by changes in the scanner over time after product shipment.

  Although the sampling clock has been described above as an example, the above-described problem may occur in general image synchronization signals generated based on the scanning synchronization signal output from the scanner. Examples of the image synchronization signal include a sampling clock, a horizontal synchronization signal, a vertical synchronization signal, and an image valid signal.

  In light of the above circumstances, an object of one aspect of the present invention is to provide a technique for correcting a sampling timing shift.

  An optical scanning device according to an aspect of the present invention includes a scanner that moves a condensing position of illumination light applied to a sample, a photodetector that detects light from the sample irradiated with the illumination light, and the scanner Image synchronization signal generation means for generating an image synchronization signal for limiting the timing for sampling the signal output from the photodetector based on a scanning synchronization signal indicating the scanning timing of the image synchronization signal, Comprises phase shift means for shifting the phase of the image synchronization signal in accordance with a phase shift amount which is a phase amount determined based on the scanning frequency of the scanner.

  According to another aspect of the present invention, there is provided an image synchronization signal adjustment method, wherein a signal output from a photodetector included in the optical scanning device is obtained based on a scanning synchronization signal indicating scanning timing of a scanner included in the optical scanning device. An image synchronization signal for limiting the sampling timing is generated, and the phase of the image synchronization signal is shifted according to a phase shift amount that is a phase amount determined based on the scanning frequency of the scanner.

  According to the above aspect, the sampling timing shift can be corrected.

1 is a diagram illustrating a configuration of a scanning microscope 100 according to a first embodiment. 5 is a diagram illustrating an example of a scanning method by the scanning microscope 100. FIG. It is the figure which showed an example of the IZ curve. 2 is a diagram illustrating a hardware configuration of a computer 20. FIG. 3 is a block diagram illustrating an example of a configuration of a clock generation circuit 15. FIG. It is a figure which shows the relationship between the sampling clock output from the clock generation circuit 15, and the scanning position of a X direction. 6 is a diagram illustrating frequency characteristics of a clock generation circuit 15. FIG. 4 is a flowchart of a first adjustment process performed by the scanning microscope 100. It is a flowchart of an image acquisition process. 12 is a flowchart of second adjustment processing performed by the scanning microscope 100. It is a figure for demonstrating the relationship between the shift | offset | difference of a sampling timing, and the linearity of an image. 3 is a block diagram illustrating an example of a configuration of a clock generation circuit 50. FIG. It is a flowchart of the 2nd adjustment process performed with the scanning microscope which concerns on 2nd Embodiment. It is a figure for demonstrating the relationship between the shift | offset | difference of a sampling timing, and the position shift of an image.

[First Embodiment]
FIG. 1 is a diagram illustrating the configuration of a scanning microscope 100 according to this embodiment. FIG. 2 is a diagram illustrating an example of a scanning method using the scanning microscope 100. FIG. 3 is a diagram showing an example of the IZ curve.

  The scanning microscope 100 is an optical scanning device that scans the sample S with laser light that is illumination light, and is a confocal microscope that includes a confocal optical system. The scanning microscope 100 is also used as, for example, a three-dimensional measurement apparatus that generates height information (including surface roughness information) of the sample S. In this specification, a position on the sample S where the laser beam is condensed and a light spot is formed is referred to as a scanning position, and a trajectory along which the light spot moves is referred to as a scanning trajectory.

  As shown in FIG. 1, the scanning microscope 100 includes a microscope main body 10, a computer 20, a display device 30, and an input device 40. The microscope main body 10 includes a scanning optical system, a photodetector 13, a scanning drive control circuit 14, an A / D converter 16, a displacement meter 17, a focus moving mechanism 18, and an image synchronization signal generation circuit 19. The scanning optical system includes a laser 1, a mirror 2, a half mirror 3, a two-dimensional scanning mechanism 4, a mirror 5, a lens 6, a revolver 7, an objective lens 8, a stage 9, a lens 11, and a confocal stop 12. The image synchronization signal generation circuit 19 includes a clock generation circuit 15.

  The two-dimensional scanning mechanism 4 includes a scanner 4 a and a scanner 4 b that move the condensing position of the laser light applied to the sample S in directions orthogonal to each other, and is controlled by the scanning drive control circuit 14. The scanner 4 a is, for example, a resonance scanner that scans the sample S in the X direction orthogonal to the optical axis of the objective lens 8. The scanner 4b is, for example, a galvano scanner that scans the sample S in the Y direction orthogonal to the optical axis of the objective lens 8 and the X direction. In the two-dimensional scanning mechanism 4, the scanner 4a scans the sample S at a higher speed than the scanner 4b.

  The confocal stop 12 is a stop in which a pinhole is formed. The confocal stop 12 is arranged so that a pinhole is positioned at a position optically conjugate with the front focal position of the objective lens 8 in order to block light reflected at a position other than the front focal position of the objective lens 8. ing. For example, the confocal stop 12 is disposed on the rear focal plane of the lens 11.

  The light detector 13 detects light from the sample S irradiated with the laser light and outputs an analog signal corresponding to the detected light intensity. The photodetector 13 is, for example, a photomultiplier tube (PMT).

  The scanning drive control circuit 14 is a scanning control unit that controls the two-dimensional scanning mechanism 4, and controls the two-dimensional scanning mechanism 4 so that raster scanning is performed. Hereinafter, the cycle of line scanning (scanning in the X direction in FIG. 2) constituting the raster scan is referred to as a scanning cycle. The scanning drive control circuit 14 outputs a scanning synchronization signal (hereinafter referred to as a scanning timing signal) indicating the scanning timing of the scanner 4 a to the clock generation circuit 15 included in the image synchronization signal generation circuit 19. The scan timing signal is, for example, a scan synchronization signal indicating the start timing of each line scan in the X direction by the scanner 4a.

  The clock generation circuit 15 is a clock generation unit that generates a sampling clock indicating the timing for sampling the analog signal output from the photodetector 13 based on the scanning timing signal. The sampling clock is an example of an image synchronization signal that limits the timing for sampling the analog signal output from the photodetector 13. The sampling clock generated by the clock generation circuit 15 is output to the A / D converter 16. In this specification, the sampling position refers to the scanning position where sampling is performed, and the sampling locus refers to the locus of the sampling position.

  The A / D converter 16 is a sampling unit that samples the analog signal output from the photodetector 13 and outputs a digital signal corresponding to the light intensity detected by the photodetector 13. The digital signal indicates the luminance value at the sampling position. The A / D converter 16 samples the analog signal according to the sampling clock generated by the clock generation circuit 15.

  The displacement meter 17 is a means for measuring the amount of movement of the objective lens 8 that moves together with the revolver 7 in the optical axis direction. The displacement meter 17 is configured to output the amount of movement of the objective lens 8 in the optical axis direction to the computer 20.

  The focal point movement mechanism 18 is a means for moving the revolver 7 in the optical axis direction. The focal point moving mechanism 18 may include, for example, a stepping motor or may include a piezo element. Since the focal point moving mechanism 18 may be any mechanism that changes the distance between the objective lens 8 and the sample S, the stage 9 may be moved in the optical axis direction instead of the revolver 7. In that case, the displacement meter 17 is configured to measure the amount of movement of the stage 9 in the optical axis direction. The amount of movement corresponds to the Z position, which is a coordinate in the Z direction.

  The image synchronization signal generation circuit 19 is an image synchronization signal generation unit that generates an image synchronization signal based on the scanning synchronization signal. In addition to the sampling clock generated by the clock generation circuit 15, a horizontal synchronization signal, a vertical synchronization signal, an image valid signal, and the like are generated. The sampling clock, the horizontal synchronization signal, the vertical synchronization signal, and the image valid signal are all examples of the image synchronization signal that limits the timing for sampling the analog signal output from the photodetector 13. The horizontal synchronization signal, vertical synchronization signal, and image valid signal are output to the computer 20.

  In the microscope main body 10, the laser light emitted from the laser 1 reflects the mirror 2 and enters the mirror 5 via the half mirror 3 and the two-dimensional scanning mechanism 4. The laser beam reflected by the mirror 5 in the direction of the optical axis of the objective lens 8 is enlarged to a predetermined light beam diameter by the lens 6 and forms a light spot on the sample S arranged on the stage 9 by the objective lens 8. The laser light reflected from the sample S enters the objective lens 8 again, and enters the half mirror 3 through the lens 6, the mirror 5, and the two-dimensional scanning mechanism 4. The laser beam reflected by the half mirror 3 is collected by the lens 11 and detected by the photodetector 13 through a pinhole formed in the confocal stop 12.

  In the scanning microscope 100, the A / D converter 16 repeats sampling while moving the scanning position in the X direction and the Y direction by the two-dimensional scanning mechanism 4, thereby each sampling distributed in two dimensions in the X direction and the Y direction. A digital signal of the position (that is, the luminance value at each sampling position) can be obtained. Further, the above processing is repeated every time the scanning position is moved in the Z direction by the focal point moving mechanism 18, so that the digital signals (that is, the respective sampling positions) distributed in three dimensions in the X direction, the Y direction, and the Z direction are obtained. Brightness value of the position) can be obtained.

  The computer 20 is image data generating means for generating scanned image data representing a tomographic image of the sample S based on the digital signal output from the A / D converter 16. The computer 20 two-dimensionally maps the digital signals at the sampling positions distributed in two dimensions in the X and Y directions output from the A / D converter 16 according to the sampling positions using a horizontal synchronization signal or the like. Thus, the scanned image data is generated.

  The computer 20 also calculates a luminance change curve (hereinafter referred to as an IZ curve) for each pixel area of the scanned image data based on the digital signals at a plurality of sampling positions different in the Z direction and the Z position output from the displacement meter 17. ) Is generated. Then, the height information of the sample S is generated by specifying the height of the pixel region based on the IZ curve. For example, as shown in FIG. 3, the computer 20 may specify the height Z0 indicating the maximum luminance value I0 among the heights of the positions where sampling is performed as the height of the pixel region. Further, the computer 20 may calculate the shape of the IZ curve, and specify the height at which the luminance value is maximum on the IZ curve as the height of the pixel region. In FIG. 3, black circles indicate the sampling results. Furthermore, the computer 20 may generate omnifocal image data focused on the entire scanning range based on pixel data corresponding to the height specified for each pixel region.

  FIG. 4 is a diagram illustrating a hardware configuration of the computer 20. The computer 20 is, for example, a standard computer and includes a processor 21, a memory 22, an input / output interface 23, a storage 24, and a portable recording medium driving device 25 into which a portable recording medium 26 is inserted. The buses 27 are connected to each other. FIG. 4 is an example of the hardware configuration of the computer 20, and the computer 20 is not limited to this configuration.

  The processor 21 is, for example, a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a DSP (Digital Signal Processor), and the like, and executes a programmed process by executing a program. Note that examples of programmed processing include, for example, image data generation processing for generating image data such as a scanned image and an omnifocal image, and height measurement processing for calculating IZ curves to generate height information.

  The memory 22 is, for example, a RAM (Random Access Memory), and temporarily stores a program or data recorded in the storage 24 or the portable recording medium 26 when the program is executed. The input / output interface 23 is a circuit that exchanges signals with devices other than the computer 20 (for example, the A / D converter 16, the display device 30, the input device 40, and the like).

  The storage 24 is, for example, a hard disk or a flash memory, and is mainly used for recording various data and programs. The portable recording medium driving device 25 accommodates a portable recording medium 26 such as an optical disk or a compact flash (registered trademark). The portable recording medium 26 has a role of assisting the storage 24.

  The display device 30 is a display that displays an image of the sample S based on image data generated by the computer 20. The display device 30 may be, for example, a liquid crystal display or an organic EL display. The display device 30 may display an image of the sample S based on the latest image data each time the computer 20 generates image data, or may display various information other than the image of the sample S. Good. In addition to images, the display device 30 also displays measurement results, measurement conditions, and the like.

  The input device 40 is an input device that inputs a command corresponding to a user operation to the computer 20. The input device 40 is, for example, a mouse, a keyboard, a touch panel, or the like.

  FIG. 5 is a block diagram showing an example of the configuration of the clock generation circuit 15 according to the present embodiment. FIG. 6 is a diagram showing the relationship between the sampling clock output from the clock generation circuit 15 and the scanning position in the X direction. Hereinafter, a clock generation circuit 15 that generates a sampling clock synchronized with the operation speed of the scanner 4a will be described with reference to FIGS. The configuration illustrated in FIG. 5 is merely an example of the configuration of the clock generation circuit 15 when the scanner 4a is a resonant scanner, and the configuration of the clock generation circuit 15 is not limited to the configuration illustrated in FIG.

  The clock generation circuit 15 includes a phase comparator 51, a loop filter 52, a voltage controlled oscillator (hereinafter referred to as VCO) 53, a counter 54, a memory 55, a D / A converter 56, a VCO 57, a counter 58, and a phase comparison. A device 59 and a loop filter 60 are provided.

  The phase comparator 51 receives a scanning timing signal output from the scanning drive control circuit 14 and a timing signal output from the counter 54 (hereinafter referred to as a first timing signal). The first timing signal will be described later. The phase comparator 51 detects a phase difference between two input signals (scanning timing signal and first timing signal) and outputs a signal corresponding to the phase difference. For example, as the first timing signal is earlier than the scanning timing signal, a lower voltage signal is output, and as the first timing signal is later, a higher voltage signal is output.

  The signal output from the phase comparator 51 is input to the VCO 53 via the loop filter 52 that is a low-pass filter. The VCO 53 is a variable frequency oscillator and generates a clock having a frequency corresponding to an input signal (voltage). For example, a high frequency clock is generated as a high voltage is input, and a low frequency clock is generated as a low voltage is input.

  The counter 54 counts the clock from the VCO 53 and outputs a first timing signal to the phase comparator 51 each time it counts a preset number of times C1 (for example, 1000 times). The counter 54 also outputs the first timing signal to a phase comparator 59 described later.

  The scanning timing signal and the first timing signal converge in the same period and substantially in the same phase by the loop composed of the phase comparator 51 to the counter 54. For this reason, in the convergence state, the same number of clocks as the number of times C1 are output from the VCO 53 at regular time intervals during one scanning cycle. That is, a clock with a constant frequency is output from the VCO 53. Note that a steady deviation caused by the frequency characteristics of the clock generation circuit 15 occurs in the phases of the scanning timing signal and the first timing signal.

  The memory 55 has at least the same number of addresses (for example, 0 to 999) as the number of times C1 set in the counter 54, and each address reproduces the velocity waveform (sine waveform) of the scanner 4a. Speed information is stored. For example, the speed information of the scanner 4a at the timing of (N-1) / C1 cycle is stored in the Nth address number.

  Each time the counter 54 counts, the D / A converter 56 reads speed information from the address of the memory 55 corresponding to the counter value and converts it into an analog signal. As a result, a voltage that reproduces the velocity waveform (sine waveform) of the scanner 4 a is output to the VCO 57.

  The VCO 57 is a variable frequency oscillator similar to the VCO 53, and generates a clock having a frequency corresponding to an input signal (voltage). Therefore, when the speed of the scanner 4a is high and the input voltage is high, a clock is output at a high frequency, and when the speed is low and the input voltage is low, a clock is output at a low frequency. The clock output from the VCO 57 is output to the A / D converter 16 as a sampling clock.

  The counter 58 counts the clock from the VCO 57 and outputs a second timing signal to the phase comparator 59 each time it counts a preset number of times C2 (for example, 2048 times). The phase comparator 59 detects the phase difference between the first timing signal output from the counter 54 and the second timing signal output from the counter 58 and outputs a signal corresponding to the phase difference. For example, as the second timing signal is earlier than the first timing signal, a lower voltage signal is output, and as the second timing signal is slower, a higher voltage signal is output.

  The signal output from the phase comparator 59 is input to the D / A converter 56 via the loop filter 60 that is a low-pass filter. The D / A converter 56 adjusts the magnitude of the analog signal according to the signal from the phase comparator 59 and outputs it.

  Since the first timing signal and the second timing signal converge in the same cycle and substantially in the same phase by the loop composed of the counter 54 and the loop filter 60, the scanning timing signal and the second timing signal are also in the same cycle and substantially the same. Converge to phase. Note that a steady deviation caused by the frequency characteristics of the clock generation circuit 15 also occurs in the phases of the scanning timing signal and the second timing signal.

  The clock generation circuit 15 further includes a phase shift circuit 54 a that is a shift unit that shifts the phase of the sampling clock output from the clock generation circuit 15 based on the phase shift instruction input from the computer 20. More specifically, the phase shift instruction includes an amount for shifting the phase of the sampling clock (hereinafter referred to as phase shift amount). The amount of phase shift is, for example, a steady deviation amount. The phase shift circuit 54a is configured to shift the phase of the sampling clock according to the phase shift amount included in the phase shift instruction. The phase shift circuit 54a is an example of a phase shift unit that shifts the phase of the image synchronization signal according to the phase shift amount that is a phase amount determined based on the scanning frequency of the scanner 4a. include.

  There is no particular limitation on the method by which the clock generation circuit 15 shifts the phase of the sampling clock. For example, the phase shift circuit 54a may adjust the relationship between the counter value of the counter 54 and the address of the memory 55 based on the steady-state deviation amount included in the phase shift instruction. For example, the phase shift circuit 54a may adjust the initial value of the counter 54 based on the steady-state deviation amount. In any case, the speed information is read from the memory 55 in consideration of the deviation between the scanning timing signal and the first and second timing signals due to the steady deviation. For this reason, the phase of the sampling clock is shifted by the steady deviation amount due to the adjustment, and the phase shift between the sampling clock and the scanning timing signal caused by the steady deviation is corrected.

  As a result, in the convergence state, the VCO 57 outputs the same number of sampling clocks as the number of times C2 in one scanning cycle at a timing at which the scanning position moves at equal intervals. That is, the sampling clock synchronized with the operation speed of the scanner 4a is output from the VCO 57 as shown in FIG.

  FIG. 7 is a diagram illustrating frequency characteristics of the clock generation circuit 15. As shown in FIG. 7, the clock generation circuit 15 has predetermined gain characteristics and phase characteristics. For this reason, a gain and a phase change according to the frequency of an input signal. This means that the steady-state deviation changes according to the scanning frequency (that is, the resonance frequency) of the scanner 4a. The scanning frequency of the scanner 4a also changes depending on the temperature change or aging of the scanner 4a. For example, when the hinge of the scanner 4a becomes soft due to a change with time, the resonance frequency is lowered, and accordingly, a phase change occurs in addition to the steady deviation. Therefore, in the scanning microscope 100, an adjustment process is performed to cope with changes in the steady deviation.

  FIG. 8 is a flowchart of the first adjustment process performed by the scanning microscope 100. FIG. 9 is a flowchart of the image acquisition process. FIG. 10 is a flowchart of the second adjustment process performed by the scanning microscope 100. Hereinafter, the adjustment process performed by the scanning microscope 100 will be specifically described with reference to FIGS. 8 to 10. Note that the first adjustment process and the second adjustment process shown in FIGS. 8 and 10 are examples of an image synchronization signal adjustment method.

  The first adjustment process shown in FIG. 8 is performed at the time of product shipment with the scanning microscope 100, for example. When the first adjustment process is started, the scanning microscope 100 first acquires an image (step S10).

  In step S <b> 10, the scanning drive control circuit 14 controls the scanner 4 a and outputs a scanning timing signal to the clock generation circuit 15. As a result, as shown in FIG. 9, the scanner 4a is driven (step S11), and the clock generation circuit 15 generates a sampling clock (step S12). Further, according to the generated sampling clock, the A / D converter 16 samples the analog signal from the photodetector 13 (step S13). Thereafter, the computer 20 generates image data based on the digital signal output from the A / D converter 16 (step S14).

  When the image is acquired, the scanning microscope 100 displays the image on the display device 30 based on the generated image data (step S20). The user of the microscope can recognize whether or not distortion has occurred in the image by visually recognizing the image displayed on the display device 30.

  When the microscope user who visually recognizes the image instructs the phase adjustment of the sampling clock (step S30 YES), the scanning microscope 100 shifts the phase of the sampling clock (step S40). Here, the phase shift circuit 54a that has received the phase shift instruction from the computer 20 shifts the phase of the sampling clock output from the clock generation circuit 15, and stores the shifted setting in the phase shift circuit 54a. Thereafter, the scanning microscope 100 repeats the processing from step S10 to step S40 until the microscope user instructs the completion of the sampling clock phase adjustment (NO in step S30).

  When the adjustment is completed, the scanning microscope 100 records the scanning frequency of the scanner 4a as a reference frequency (step S50), and ends the first adjustment process. Here, the computer 20 stores the scanning frequency of the scanner 4a in the storage 24 as a reference frequency. The scanning frequency of the scanner 4 a is input to the computer 20 by the microscope user using the input device 40. The method for specifying the scanning frequency of the scanner 4a by the microscope user is not particularly limited. For example, the scanning frequency of the scanner 4a may be specified by inputting a scanning timing signal to a frequency measuring device.

  The second adjustment process shown in FIG. 10 is periodically performed by the scanning microscope 100 after product shipment, for example. When the second adjustment process is started, the scanning microscope 100 first acquires an image (step S100). This process is the same as step S10 in FIG.

  When the image is acquired, the scanning microscope 100 acquires a reference frequency (step S110). Here, the computer 20 reads the reference frequency stored in the storage 24 and displays it on the display device 30.

  Thereafter, when the microscope user who has specified the scanning frequency of the scanner 4a instructs the phase adjustment of the sampling clock (YES in step S120), the scanning microscope 100 shifts the phase of the sampling clock (step S130). Here, the microscope user first determines the amount of phase shift based on the scanning frequency of the scanner 4a. More specifically, the amount of phase shift is determined based on the phase characteristic of the clock generation circuit 15 based on the difference between the reference frequency and the scanning frequency of the scanner 4a. Thereafter, the user of the microscope uses the input device 40 to input a phase shift instruction including the phase shift amount to the computer 20. The phase shift circuit 54a that has received the phase shift instruction from the computer 20 shifts the phase of the sampling clock according to the phase shift amount determined based on the scanning frequency of the scanner 4a, and sets the shifted setting to the phase shift circuit 54a. save.

  Finally, the scanning microscope 100 records the scanning frequency of the scanner 4a as a reference frequency (step S140), and ends the second adjustment process. Here, the computer 20 stores the scanning frequency of the scanner 4a in the storage 24 as a reference frequency, and updates the reference frequency. The scanning frequency of the scanner 4a is input to the computer 20 by a microscope user using the input device 40, as in step S50 of FIG.

  According to the scanning microscope 100, by performing the first adjustment process and the second adjustment process, even when the scanning frequency of the scanner 4a changes due to a change over time or the like, sampling is caused by the change in the scanning frequency. Timing deviation can be corrected. For this reason, there is almost no sampling position error as shown in the graph G1 in FIG. 11A, and sampling can be performed at spatially spaced sampling positions as shown in the image diagram P1. Therefore, the linearity of the image is maintained well.

  FIGS. 11B and 11C show how sampling positions are not spatially spaced as a result of sampling timing shifts. In the state shown in FIGS. 11B and 11C, the linearity of the image is deteriorated and the image is greatly distorted as shown in the graph G2 and the graph G3 and the image diagram P2 and the image diagram P3.

  In addition, since the scanning microscope 100 has little deterioration in image quality due to environmental changes or the like, an image suitable for high-precision measurement can be acquired. Further, since the phase shift amount is determined based on the scanning frequency, it is possible to correct the sampling timing shift with higher accuracy than in the case where the phase shift amount is determined based on the image information depending on the image resolution. Therefore, correction can be performed before the image is affected, and stable and highly accurate measurement can be performed when used as a measuring apparatus.

[Second Embodiment]
FIG. 12 is a block diagram showing an example of the configuration of the clock generation circuit 50 included in the scanning microscope according to the second embodiment. FIG. 13 is a flowchart of a second adjustment process performed by the scanning microscope according to the second embodiment.

  The scanning microscope according to the second embodiment is different from the scanning microscope 100 in that a clock generation circuit 50 is provided instead of the clock generation circuit 15. Other configurations are the same as those of the scanning microscope 100. In the scanning microscope according to the second embodiment, the second adjustment process shown in FIG. 13 is performed instead of the second adjustment process shown in FIG. Note that, also in the scanning microscope according to the second embodiment, the first adjustment process shown in FIG.

  The clock generation circuit 50 shown in FIG. 15 is different from the clock generation circuit 15 shown in FIG. 5 in that it includes a phase shift control unit 70 that controls the amount of phase shift according to the scanning frequency. The phase shift control unit 70 includes a frequency detection unit 71 that detects the scanning frequency of the scanner 4a, a phase shift amount determination unit 72 that determines the phase shift amount, and a storage unit 73 that stores the phase characteristics of the clock generation circuit 50. ing.

  The frequency detector 71 is a frequency detector that detects the scanning frequency of the scanner 4a. The frequency detector 71 may include a crystal oscillator that outputs a clock with a stable frequency. For example, the frequency detection unit 71 may detect the scanning frequency of the scanner 4 a by counting the clock output from the crystal oscillator during the period of the scanning timing signal output from the scanning drive control circuit 14. Further, the frequency detection unit 71 uses a timing signal on the output side of the clock generation circuit 50 such as a second timing signal output from the counter 58 instead of the scanning timing signal output from the scanning drive control circuit 14. The scanning frequency of the scanner 4a may be detected. In the detection of the scanning frequency, an abnormal value filtering process, a process of calculating a statistical value such as a mode value, an average value, and a center value within a fixed time may be performed.

  The phase shift amount determination unit 72 is a phase shift amount determination unit that determines the phase shift amount based on the scanning frequency of the scanner 4 a detected by the frequency detection unit 71. The phase shift amount determination unit 72 may determine the phase shift amount based on the difference between the reference frequency and the scanning frequency of the scanner 4 a detected by the frequency detection unit 71. For example, the phase shift amount may be determined from the difference between the reference frequency and the scanning frequency of the scanner 4a with reference to the phase characteristics stored in the storage unit 73. The storage unit 73 is an example of a storage unit that stores the phase characteristics of the image synchronization signal generation unit.

  The phase characteristic of the clock generation circuit 50 can be acquired by measuring the phase change of the sampling clock due to the sweep of the input frequency to the clock generation circuit 50, for example. The phase characteristic stored in the clock generation circuit 50 may be obtained in advance by this method. The phase characteristic may be held as a specific value in a table format or as a relational expression.

  The second adjustment process shown in FIG. 13 is automatically performed by a scanning microscope. For example, in order to cope with a change with time, it may be performed at predetermined time intervals by a timer. Further, it may be additionally performed at the timing when the change of the device environment is detected.

  When the second adjustment process is started, the scanning microscope first acquires a reference frequency (step S200). Here, the computer 20 reads the reference frequency stored in the storage 24.

  Next, the scanning microscope detects a scanning frequency (step S210). Here, the frequency detector 71 detects the scanning frequency of the scanner 4a based on the scanning timing signal output from the scanning drive control circuit 14, for example.

  Thereafter, the scanning microscope determines whether the sampling clock needs to be shifted (step S220). Here, the phase shift amount determination unit 72 determines whether or not the sampling clock needs to be shifted based on the reference frequency acquired in step S200 and the scanning frequency detected in step S210. The phase shift amount determination unit 72 may determine to shift the sampling clock when, for example, a difference of a predetermined frequency or more occurs between the reference frequency and the scanning frequency. In addition, the phase shift amount determination unit 72 refers to the phase characteristics stored in the storage unit 73, for example, when the phase variation amount between the reference frequency and the scanning frequency is a predetermined amount or more, the sampling clock It may be decided to perform the shift.

  When it is determined to shift the sampling clock, the scanning microscope determines the amount of phase shift (step S230). Here, the phase shift amount determination unit 72 refers to the phase characteristics stored in the storage unit 73 and determines the phase shift amount from the difference between the reference frequency and the scanning frequency of the scanner 4a. When the frequency fluctuation range of the scanner 4a (for example, from the frequency F1 to the frequency F2 shown in FIG. 7) is narrow, the phase shift amount determination unit 72 determines the phase shift amount based on the phase characteristics approximated by a straight line. May be. Thereafter, a phase shift instruction including the determined phase shift amount is output from the phase shift control unit 70 to the phase shift circuit 54a.

  When the phase shift amount is determined, the scanning microscope shifts the phase of the sampling clock (step S240). Here, the phase shift circuit 54a shifts the phase of the sampling clock, which is an example of the image synchronization signal, according to the phase shift amount determined by the phase shift amount determination unit 72 in step S230, and shifts the setting after the shift. Saved in the circuit 54a.

  Finally, the scanning microscope records the scanning frequency of the scanner 4a as a reference frequency (step S250), and ends the second adjustment process. Here, the computer 20 stores the scanning frequency of the scanner 4a detected in step S210 in the storage 24 as a reference frequency, and updates the reference frequency.

  Even in the scanning microscope according to the present embodiment, similarly to the scanning microscope 100, even when the scanning frequency of the scanner 4a changes due to a change over time or the like, the sampling timing shift caused by the change in the scanning frequency is corrected. be able to. The same is true in that stable and highly accurate measurement can be performed when used as a measuring apparatus. Furthermore, according to the scanning microscope according to the present embodiment, a change in the scanning frequency of the scanner 4a due to a change over time or the like is automatically detected, and a sampling timing shift caused by the change in the scanning frequency is automatically corrected. Can do.

  The embodiments described above show specific examples for facilitating understanding of the invention, and the embodiments of the present invention are not limited to these. The optical scanning device and the image synchronization signal adjustment method can be variously modified and changed without departing from the scope of the claims.

  In the embodiment described above, the optical scanning device that is a confocal microscope is illustrated, but the optical scanning device may be another scanning microscope device such as a two-photon excitation microscope. Moreover, although the example in which the scanner 4a is a resonance scanner has been shown, the scanner 4a may be a galvano scanner. The steady deviation due to the frequency characteristics of the clock generation circuit can occur even when generating sampling clocks that occur at regular intervals in time. For this reason, even when the scanner 4a is a galvano scanner, it is effective to correct the sampling timing shift by the phase shift of the sampling clock.

  In the second embodiment, the clock generation circuit 50 includes the phase shift amount determination unit 72. However, the computer 20 may function as the phase shift amount determination unit 72. For example, the clock generation circuit may output the detected scanning frequency to the computer 20, and the computer 20 may determine whether or not the phase shift is necessary and the amount of phase shift. In this case, the phase shift instruction is output from the computer 20 to the clock generation circuit.

  In the second embodiment, the phase characteristic of the clock generation circuit 50 acquired in advance is stored in the storage unit 73. However, the phase characteristic of the clock generation circuit 50 is dominantly affected by a specific circuit. If it is known that the clock generation circuit 50 is received, the phase characteristic of the clock generation circuit 50 may be estimated from the phase characteristic of the specific circuit.

  In the above-described embodiment, an example in which the scanning frequency of the scanner is directly detected has been shown. However, the relationship between the scanning frequency and other information of the scanner (for example, the temperature and amplitude of the scanner) is acquired in advance by measurement. The scanning frequency may be estimated by measuring these pieces of information.

  Further, the sampling timing shift is caused not only by the clock generation circuit but also by a steady deviation caused by the frequency characteristics of the image synchronization signal generation circuit. For example, when a steady deviation occurs in the circuit that generates the horizontal synchronization signal, a phase shift occurs between the actual drive waveform of the scanner 4b and the horizontal synchronization signal, resulting in a shift in the sampling position in the Y direction. FIG. 14 shows images (image M1, image M2, and image M3) that are acquired when the scanner 4b operates at different scanning frequencies side by side, and a positional shift caused by frequency characteristics occurs between the images. Is shown. For this reason, the circuit that generates the horizontal movement signal may be provided with a phase shift unit that shifts the phase of the horizontal synchronization signal in accordance with the phase shift amount determined based on the scanning frequency of the scanner 4b. Further, the same phase shift means may be provided in the circuit for generating the vertical same signal and the image effective signal.

  DESCRIPTION OF SYMBOLS 1 ... Laser, 2, 5 ... Mirror, 3 ... Half mirror, 4 ... Two-dimensional scanning mechanism, 4a, 4b ... Scanner, 6, 11 ... Lens, 7 ... Revolver, 8 ... objective lens, 9 ... stage, 10 ... microscope body, 12 ... confocal stop, 13 ... photodetector, 14 ... scanning drive control circuit, 15 ... Clock generation circuit 16 ... A / D converter 17 ... displacement meter 18 ... focus movement mechanism 19 ... image synchronization signal generation circuit 20 ... computer 21 ... Processor, 22 ... Memory, 23 ... Input / output interface, 24 ... Storage, 25 ... Portable recording medium drive device, 26 ... Portable recording medium, 27 ... Bus, 30 ... ..Display device, 40 ... input device, 50 ... clock generation circuit, 5 , 59 ... Phase comparator, 52, 60 ... Loop filter, 53, 57 ... VCO, 54, 58 ... Counter, 54a ... Phase shift circuit, 55 ... Memory, 56 ..D / A converter, 70 ... phase shift control unit, 71 ... frequency detection unit, 72 ... phase shift amount determination unit, 73 ... storage unit, 100 ... scanning microscope, S ···sample

Claims (9)

A scanner that moves the condensing position of the illumination light that irradiates the sample;
A photodetector for detecting light from the sample irradiated with the illumination light;
An image synchronization signal generating means for generating an image synchronization signal for limiting a timing for sampling a signal output from the photodetector based on a scanning synchronization signal indicating a scanning timing of the scanner;
The optical scanning apparatus according to claim 1, wherein the image synchronization signal generating unit includes a phase shift unit that shifts a phase of the image synchronization signal in accordance with a phase shift amount that is a phase amount determined based on a scanning frequency of the scanner. The optical scanning device according to claim 1, further comprising:
Sampling means for sampling the signal output from the photodetector according to a sampling clock which is the image synchronization signal,
The image synchronization signal generation means is configured to generate the sampling clock based on the scanning synchronization signal,
The optical scanning device characterized in that the phase shift means is configured to shift the phase of the sampling clock in accordance with the phase shift amount. The optical scanning device according to claim 2, further comprising:
An optical scanning device comprising image data generation means for generating image data of the sample based on a signal output from the sampling means. The optical scanning device according to claim 1, further comprising:
A phase shift amount determining means for determining the phase shift amount;
The optical scanning device, wherein the phase shift means shifts the phase of the image synchronization signal in accordance with the phase shift amount determined by the phase shift amount determination means. The optical scanning device according to claim 1, further comprising:
A frequency detection means for detecting a scanning frequency of the scanner;
A phase shift amount determining means for determining the phase shift amount based on a scanning frequency of the scanner detected by the frequency detecting means,
The optical scanning device, wherein the phase shift means shifts the phase of the image synchronization signal in accordance with the phase shift amount determined by the phase shift amount determination means. The optical scanning device according to claim 4 or 5,
The optical scanning device characterized in that the phase shift amount determination means determines the phase shift amount based on a difference between a reference scanning frequency and a scanning frequency of the scanner. The optical scanning device according to any one of claims 4 to 6, further comprising:
A storage unit storing the phase characteristics of the image synchronization signal generating means;
The optical scanning device, wherein the phase shift amount determining means determines the phase shift amount with reference to the phase characteristics stored in the storage unit. The optical scanning device according to any one of claims 1 to 7,
The scanner is a resonant scanner;
The scanning frequency of the scanner is the resonant frequency of the resonant scanner. Based on the scanning synchronization signal indicating the scanning timing of the scanner included in the optical scanning device, generates an image synchronization signal that limits the timing for sampling the signal output from the photodetector included in the optical scanning device,
An image synchronization signal adjustment method, wherein the phase of the image synchronization signal is shifted according to a phase shift amount that is a phase amount determined based on a scanning frequency of the scanner.