JP2012118195A - Microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the decrease of a driving amplitude of a piezoelectric element when driving the piezoelectric element provided in a microscope at a high speed.SOLUTION: When reciprocating and driving a piezoelectric element as a linear motion mechanism at a predetermined cycle, if a drive signal is a cosine wave as shown by a curve C12, the maximum value of the driving amplitude of the piezoelectric element is decreased due to response delay of the piezoelectric element. Then, a cycle of a cosine wave component as the drive signal is shortened while a cycle of the whole drive signal is fixed, and a dormant section having a fixed value is inserted into a section where a rate of change of the cosine wave becomes zero (0) by the amount of shortening, thus obtaining a drive signal shown by a curve C13. When the piezoelectric element is driven by this drive signal, the reduction rate of the maximum value of the driving amplitude of the piezoelectric element decreasing due to high-speed driving can be reduced. This invention can be applied to a scanning type microscope.

Description

  The present invention relates to a microscope capable of reducing a decrease in driving amplitude of a piezo element when the piezo element provided in the microscope is driven at high speed.

  Conventionally, when a drive mechanism using a piezo element is periodically driven, the piezo element is driven by a drive signal such as a sawtooth wave, a sine wave (the phase of the cosine wave is shifted by π / 2), a staircase wave, or a triangular wave. It is generally known to drive.

  For example, in the invention described in Patent Document 1, the piezo element is driven by a triangular wave-like drive signal, and is driven for a predetermined period at the change point of the drive signal in order to suppress vibration at the output operation point of the displacement magnifying mechanism. There is a suspension of signal turning.

  As a drive signal generation method, a method of generating a drive signal having a complex waveform by combining an analog circuit and a digital circuit has been proposed (see, for example, Patent Document 2).

  The type of waveform signal used as the drive signal for the piezo element can be selected depending on the structure of the drive mechanism. However, when the piezo element is driven back and forth at high speed, a sine wave (cosine wave) is used as the drive signal. ) Is often used. This is because a piezo element has an inherent resonance frequency, and a drive signal having a waveform including a plurality of frequency components is likely to induce resonance.

  In the above-described signals such as a sawtooth wave and a triangular wave, only a sine wave (cosine wave) is composed of a single frequency signal. If this sine wave (cosine wave) is used as a drive signal, it is easy to avoid the induction of resonance, but other signal waveforms have a stepped portion or a portion where the drive voltage changes sharply. In addition, since these portions include a plurality of frequency components, resonance may occur.

JP-A-9-99567

JP 2008-221583 A

  In this way, when a drive mechanism using a piezo element is to be driven at high speed, driving with a sine wave (cosine wave) drive signal is required. However, when the piezo element is driven with a sine wave (cosine wave), the maximum drive amplitude of the piezo element (maximum drive amplitude) decreases as the period of the drive signal becomes shorter if the maximum amplitude of the drive signal is the same. To do.

  This is because a response delay to the drive signal occurs in the piezo element, and when the period of the drive signal is shorter than the response time of the piezo element, the amplitude of the piezo element (drive mechanism) becomes the maximum value of the amplitude of the drive signal. This is because the amplitude (drive voltage) of the drive signal starts to decrease before the corresponding magnitude is reached. Then, the drive amplitude of the piezo element increases, and braking is applied while the drive amplitude reaches the maximum value that should be originally taken, so that the drive amplitude of the piezo element starts to decrease.

  As a result, the maximum drive amplitude of the piezo element is reduced, and when the piezo element is driven at a high speed with a sine wave (cosine wave) drive signal, the design of the drive mechanism is set to the maximum of the piezo element. It was necessary to allow a reduction in drive amplitude to some extent.

  As described above, due to the physical characteristics of the piezo element, the maximum drive amplitude of the piezo element decreases as the period of the drive signal is shortened, but the maximum is possible without changing the period of the drive signal (drive period of the piezo element). It is practically useful to reduce the reduction rate of the drive amplitude.

  The present invention has been made in view of such a situation, and when driving the linear motion mechanism at high speed, the reduction in the drive amplitude of the linear motion mechanism is reduced without changing the cycle of the drive signal. Is to be able to.

  The microscope of the present invention includes a linear motion mechanism that changes a distance between a stage on which a sample to be observed is placed and an objective lens in the optical axis direction of the objective lens, the linear motion mechanism with a constant amplitude, and A predetermined time is subtracted from the first period of the cosine wave as the drive signal that is reciprocally driven with a period shorter than the drive delay time of the linear motion mechanism with respect to the drive signal that drives the linear motion mechanism, A calculating means for calculating a cosine wave of a period, and a final drive signal whose period becomes the first period by inserting a pause section having a constant value into a part of the cosine wave of the second period Drive signal generation means for supplying the final drive signal to the linear motion mechanism and drive control means for driving the linear motion mechanism to reciprocate.

  According to the present invention, when the linear motion mechanism is driven at high speed, it is possible to reduce the decrease in the drive amplitude of the linear motion mechanism without changing the cycle of the drive signal.

It is a figure explaining the outline | summary of this invention. It is a figure explaining the delay of the response with respect to a step-like drive signal. It is a figure explaining the delay of a response to a single cosine wave drive signal. It is a figure explaining the increase rate of the maximum drive amplitude. It is a figure explaining the increase in the maximum drive amplitude by insertion of a rest period. It is a figure which shows the structural example of one Embodiment of the scanning microscope to which this invention is applied. It is a figure which shows an example of a drive table. It is a flowchart explaining a drive table production | generation process. It is a flowchart explaining an observation process.

  Embodiments to which the present invention is applied will be described below with reference to the drawings.

[Outline of the present invention]
First, a method for driving a linear motion mechanism provided in a microscope to which the present invention is applied will be described. Hereinafter, a piezo element will be described as an example of a linear motion mechanism that periodically reciprocates an object with a constant amplitude.

  For example, when the piezo element is driven at a high speed near the limit of the driving speed, the piezo element is driven by a cosine wave shaped drive signal as shown by a curve C11 in FIG. In FIG. 1, the horizontal axis indicates time, and the vertical axis indicates the drive signal or the amplitude (drive amplitude) of the piezoelectric element.

  When the period of the drive signal is sufficiently long, the position of the piezo element, that is, the drive amplitude of the piezo element changes following the amplitude (drive voltage) of the drive signal as shown by a curve P11. In the example of FIG. 1, the phase of the drive amplitude indicated by the curve P11 is shifted from the drive signal indicated by the curve C11 because the response to the drive signal is delayed in the piezo element. Here, it is assumed that the drive amplitude of the piezo element, that is, the position (distance) of the object moved by the piezo element is proportional to the amplitude (drive voltage) of the drive signal.

  Furthermore, when driving continuously so that the drive amplitude of the piezo element changes periodically, if the drive signal cycle is shortened, the maximum value of the drive amplitude of the piezo element during driving is the maximum value of the amplitude of the drive signal. It becomes smaller than the size corresponding to.

  Hereinafter, the drive amplitude of the piezo element corresponding to the maximum value of the amplitude of the drive signal is also referred to as the maximum movable amplitude, and the maximum value of the drive amplitude of the piezo element during driving is also referred to as the maximum drive amplitude. That is, the maximum movable amplitude is the maximum value of the drive amplitude that the piezo element should originally reach, and the maximum drive amplitude is the maximum value of the actual amplitude of the piezo element during driving.

  For example, if the drive signal is a cosine wave having the waveform shown by the curve C12, the maximum drive amplitude of the piezo element decreases as shown by the curve P12. In the example of FIG. 1, the cycle of the drive signal indicated by the curve C12 is shorter than the cycle of the drive signal indicated by the curve C11, whereby the maximum drive amplitude of the piezo element indicated by the curve P12 is the curve P11. This is smaller than the maximum drive amplitude of the piezo element shown in FIG.

  Therefore, in the present invention, as shown by the curve C13, a drive signal having a waveform obtained by inserting a pause period in which the value is constant is generated in a portion where the rate of change of the cosine wave is 0, and the piezoelectric signal is generated by this drive signal. Driving the element reduces the decrease in the maximum drive amplitude of the piezo element.

  In the example of FIG. 1, the waveform shown by the curve C13 is provided with a pause period of a certain period in a portion where the phase of the cosine waveform is 2nπ (where n = 0, 1, 2,...). . In the rest period, the amplitude of the drive signal, that is, the drive voltage of the drive signal is set to the same value as the drive voltage value (1 in the example of the curve C13) of the portion where the rest period in the cosine wave is inserted. That is, the waveform of the drive signal is basically a cosine wave waveform, but the amplitude (drive voltage) is clamped for a certain period at a position where the amplitude of the cosine wave is maximized.

  At this time, the entire cycle of the drive signal is the same as the cycle of the drive signal before the pause interval is inserted, and the cycle of the cosine wave component is shortened by the pause interval. For example, the cycle of the drive signal shown by the curve C12 is Zt, and the cycle of the drive signal shown by the curve C13 obtained by inserting a pause section into this drive signal is also Zt.

  Note that the attenuation of the maximum drive amplitude of the piezo element indicated by the curve P12 occurs when the period of the waveform of the drive signal indicated by the curve C12 is shorter than the delay time with respect to the drive signal of the piezo element. Naturally, this has no meaning unless the time is shorter than the delay time of the piezoelectric element.

  In this way, by providing one pause interval during one cycle of the drive signal while maintaining the length of the entire cycle, the decrease rate of the maximum drive amplitude of the piezo element can be reduced as shown by the curve P13. Can be reduced. In the example of FIG. 1, the maximum drive amplitude of the piezo element after insertion of the pause period indicated by the curve P13 is larger than the maximum drive amplitude of the piezo element before insertion of the pause period indicated by the curve P12.

  Note that the position where the pause period in the drive signal is inserted is not limited to the position where the phase of the cosine wave is 2nπ, but may be another position. For example, the insertion position of the pause period may be a position where the phase of the cosine wave is (2n−1) π (where n = 1, 2,...), Or both of them. Also good.

  However, it is desirable that the insertion position of the pause period is the cosine wave, that is, the position where the phase is nπ (where n = 0, 1, 2,...). This is because, at the apex portion of the cosine wave, the rate of change of the waveform of the cosine wave is 0, so that the frequency component of the drive signal does not change even when a pause period that is a direct current component is inserted. In this case, resonance does not occur as long as the frequency of the cosine wave is within a range that does not exceed the resonance limit of the piezoelectric element.

[Length of pause section]
Next, the length of the pause period inserted into the drive signal will be described. Hereinafter, the length of the pause period inserted into the drive signal is also referred to as a standby time.

  In general, not only the piezoelectric element but also the drive unit is driven by a drive signal to move the mass, a response delay occurs in the drive unit. This is because the inertial mass of the drive system, the static friction coefficient and the dynamic friction coefficient of the movable part, etc. act on the torque generated by the drive signal.

  Here, when a stepped rectangular wave is given to the drive unit as the drive signal, the response delay of the drive unit is as shown in FIG. In FIG. 2, a curve C21 shows the waveform of the drive signal, and a curve P21 shows the drive amplitude of the drive unit. In the figure, the horizontal direction indicates time, and the vertical direction indicates the magnitude of the drive signal or drive amplitude.

  In the example of FIG. 2, the drive amplitude changes with a predetermined time delay with respect to the change of the drive signal. This delay is a delay with respect to a change in the drive signal of the entire drive system, which consists of a response delay in the drive unit and a delay caused by the inertial mass of the drive system.

  Therefore, if the cycle of the drive signal is made sufficiently long, the drive amplitude of the drive system follows the change of the drive signal, and the maximum drive amplitude does not decrease.

  On the other hand, if the cycle of the drive signal is shortened so that the amplitude of the drive signal decreases before the drive amplitude reaches the magnitude corresponding to the maximum amplitude of the drive signal, the drive amplitude corresponds to the maximum amplitude of the drive signal. Since it starts to decrease before it reaches the size, the maximum drive amplitude decreases.

  For example, consider a case where a single cosine wave is given as a drive signal to the drive unit as shown in FIG. In FIG. 3, a curve C31 shows the waveform of the drive signal, and a curve P31 shows the drive amplitude of the drive unit. In the figure, the horizontal direction indicates time, and the vertical direction indicates the magnitude of the drive signal or drive amplitude.

  In FIG. 3, the waveform of the drive signal indicated by the curve C31 is such that the drive unit is driven by the maximum movable amplitude from the stationary state and then returned to the state before the drive. On the other hand, the waveform of the drive amplitude indicated by the curve P31 changes following the drive signal. However, before the drive amplitude of the drive unit reaches the maximum movable amplitude, the amplitude of the drive signal is already at the maximum. Since it is smaller than the amplitude, the maximum drive amplitude of the drive unit is smaller than the maximum movable amplitude.

  Further, the delay time D ′ from the time when the drive signal becomes the maximum amplitude to the time when the drive amplitude becomes the maximum is a delay time consisting of a response delay generated in the drive unit, a delay generated by the action of the static friction coefficient, and the like. is there. Since the drive unit is driven from a stationary state, the delay time D ′ does not include a delay due to inertia.

  On the other hand, the delay time D from the time when the amplitude of the drive signal becomes the minimum value to the time when the drive amplitude becomes the minimum consists of a response delay that occurs in the drive unit, a delay that occurs due to the action of the dynamic friction coefficient, inertia, and the like. Delay time. Therefore, when the drive signal is a single cosine wave and the drive unit is continuously driven to reciprocate, the drive signal is delayed by the delay time D.

  For example, suppose that the time variable is t and the drive signal Y is a cosine wave represented by Y = cos (t). Here, assuming that a decrease in the maximum drive amplitude of the drive unit occurs and the drive amplitude follows the change of the drive signal in a stable state, the drive amplitude R can be approximated as R = a · cos (t + δ). . The stable state refers to a state in which the drive amplitude also changes periodically when the drive signal is changed periodically.

  Assuming that the drive unit is driven for one cycle instead of continuous driving, the waveform of the drive amplitude until the end of one cycle of the drive signal is represented by R = a · cos (t + δ). This waveform corresponds to the portion on the left side of the peak of the waveform of the drive amplitude indicated by the curve P31 in FIG.

  On the other hand, after the end of one cycle of the drive signal, the drive amplitude converges to a magnitude corresponding to the drive voltage at the end of the one cycle of the drive signal as time elapses. The drive amplitude waveform is represented by R ′ = a · cos (t + 2π) + b. This waveform corresponds to a portion on the right side of the top of the waveform of the drive amplitude indicated by the curve P31 in FIG.

  By the way, when a single cosine wave is given to the drive system as a drive signal, the maximum drive amplitude of the drive system tends to decrease as the cycle of the drive signal becomes shorter due to the response delay of the drive system as described above. There is. Specifically, it is known that the maximum drive amplitude decreases approximately linearly as the cycle of the drive signal becomes shorter.

  For example, as described above, when the pause period is inserted into the cosine wave as the drive signal without changing the cycle Zt of the entire drive signal, when the standby time is t, the cycle of the cosine wave component of the drive signal is Zt-t. The period of the cosine wave component of the drive signal becomes shorter as the standby time t is made longer, and the maximum drive amplitude is thereby reduced.

  When the standby time is t, the increase rate of the maximum drive amplitude that increases (decreases) due to a change in the period of the cosine wave component of the drive signal can be expressed by a decrease function f (t). For example, the decrease function f (t) can be set to f (t) = − kt + 1, where k is a coefficient determined by the cycle Zt of the drive signal (where 1> k). The decrease function f (t) is a function that becomes smaller as the standby time t becomes longer, and 0 <f (t) ≦ 1.

  Note that the increase rate of the maximum drive amplitude here refers to a change in the standby time t on the basis of the maximum drive amplitude when the period of the cosine wave component of the drive signal is Zt, that is, when the standby time t = 0. It is the rate of increase in the maximum drive amplitude when

  On the other hand, considering an interval of one cycle of the drive signal, as shown in FIG. 3, when a sufficient time elapses after the amplitude of the cosine wave as the drive signal becomes maximum, the drive amplitude becomes 1 of the cosine wave. It converges to a magnitude corresponding to the amplitude at the end of the cycle. Therefore, since the length from the convergence position to the maximum value of the drive amplitude of the drive unit is the actual amplitude of the drive unit, if a pause interval is inserted into the drive signal, until the standby time becomes a certain length of time, As the standby time t increases, the actual amplitude (maximum drive amplitude) of the drive unit increases.

  The increase rate of the maximum drive amplitude that increases with the waiting time t inserted in this way can be expressed by an increase function g (t), for example, the increase function g (t) is a sine function. The increase function g (t) is a function that increases as the standby time t increases, and 0 ≦ g (t) <1.

  As described above, when a pause period is inserted in the drive signal that is a cosine wave, the maximum drive amplitude of the drive unit driven by the drive signal is decreased by the decrease function f (t) due to the decrease in the period of the cosine wave component. On the other hand, the waiting time t increases by the increase function g (t).

  Therefore, the final increase rate of the maximum drive amplitude when the pause period (standby time t) is inserted into the drive signal that is a cosine wave is, for example, as shown in FIG. 4, a function V (t) = f (t ) + G (t).

  In FIG. 4, the horizontal axis indicates the standby time t, and the vertical axis indicates the increase rate of the maximum drive amplitude. A straight line f11, a curve g11, and a curve v11 indicate a decrease function f (t), an increase function g (t), and a function V (t), respectively.

  The function V (t) indicating the final increase rate of the maximum drive amplitude when the pause period is inserted is represented by the sum of the decrease function f (t) and the increase function g (t). As can be seen, the function V (t) has a value of 1 or more for each waiting time t.

  Therefore, if the rest period is inserted into the drive signal while the entire period Zt of the drive signal which is a cosine wave is fixed, and the period of the cosine wave component is shortened by that amount, the cosine wave having the period Zt is used as the drive signal. Compared to the case, a larger maximum driving amplitude can be obtained.

  Here, the standby time t at which the increase rate of the maximum drive amplitude is maximum is t when the entire cycle Zt of the drive signal is designated, and the function V (t) is maximum in the range of 0 ≦ t ≦ Zt. It is. Therefore, a function V (t) is obtained in advance for the cycle Zt of the drive signal, and at the stage of driving the drive system, a standby time t at which the function V (t) is maximized is calculated to generate a drive signal. For example, a larger maximum driving amplitude can be obtained by a simple calculation without changing the period of the driving signal. In other words, the decrease in the maximum drive amplitude can be minimized without changing the drive cycle of the drive system.

  For example, assuming that the coefficient determined by the cycle Zt of the drive signal is k, the decrease function f (t) for each cycle Zt is −kt + 1, and the increase function g (t) is A (k) · cos (π / 2− (πt / 2Zt). )), The function V (t) for each period Zt can be obtained immediately by simply substituting the coefficient k into these functions. A (k) is a function having the coefficient k as a variable.

  By inserting such a pause period into the drive signal, for example, as shown in FIG. 5, the maximum drive amplitude of the drive system can be increased.

  In FIG. 5, a curve C41 and a curve P41 indicate the waveform of the drive signal before insertion of the pause period and the waveform of the drive amplitude of the drive system, and the curve C42 and the curve P42 indicate the drive signal after insertion of the pause period. The waveform and the waveform of the drive amplitude of the drive system are shown. In the figure, the horizontal direction indicates time, and the vertical direction indicates the magnitude of the drive signal or drive amplitude.

  In FIG. 5, the drive signal indicated by the curve C41 is a cosine wave signal having a period of 62 msec. In this case, the maximum drive amplitude of the drive system is about 188 μm as shown by the curve P41.

  On the other hand, a rest period is inserted in the cosine wave signal in the drive signal shown by the curve C42, and the cycle of this drive signal is 62 msec, which is the same as the drive signal shown by the curve C41. In this case, the maximum drive amplitude of the drive system is about 227 μm as shown by the curve P42. Therefore, in the example of FIG. 5, the maximum drive amplitude is increased by about 40 μm by inserting a pause period in the drive signal without changing the cycle of the entire drive signal, that is, the drive cycle of the drive system. I understand.

[Configuration of scanning microscope]
Next, a specific embodiment of a scanning microscope to which the above-described linear motion mechanism (piezo element) driving method is applied will be described. FIG. 6 is a diagram showing a configuration example of an embodiment of a scanning microscope to which the present invention is applied.

  The scanning microscope 11 irradiates the sample 12 with illumination light as excitation light, thereby receiving fluorescence (hereinafter referred to as observation light) generated from the sample 12 and observing the observation surface of the sample 12. Consists of a confocal microscope for obtaining images.

  That is, the sample 12 is placed on the stage 21, and the illumination light emitted from the light source 22 is irradiated to the sample 12 through the optical system 23. The optical system 23 guides the observation light generated from the sample 12 to the photodetector 24.

  The optical system 23 includes at least an optical path dividing unit 25, a Y scanning mechanism 26, an X scanning mechanism 27, an objective lens 28, and a Z-axis drive mechanism 29. Illumination light from the light source 22 is transmitted from the optical path dividing unit 25 to the objective lens. The sample 12 is irradiated through 28.

  The optical path splitting unit 25 includes a dichroic mirror that transmits illumination light and reflects observation light, a lens, and the like, guides illumination light from the light source 22 to the Y scanning mechanism 26, and transmits observation light from the Y scanning mechanism 26. The light is incident on the photodetector 24.

  The Y scanning mechanism 26 is composed of a galvano scanner having a scanning mirror or the like, and deflects the illumination light from the optical path splitting unit 25 so that the illumination light is perpendicular to the optical axis direction of the objective lens 28 (hereinafter referred to as the Y direction). The observation surface of the sample 12 is scanned. Hereinafter, the optical axis direction of the objective lens 28 is also referred to as a Z direction.

  The X scanning mechanism 27 includes a resonant scanner having a scanning mirror. The X scanning mechanism 27 deflects the illumination light from the Y scanning mechanism 26 so that the illumination light is perpendicular to the Z direction and the Y direction (hereinafter, the X direction). The observation surface of the sample 12 is scanned.

  The objective lens 28 irradiates the observation surface of the sample 12 with illumination light from the X scanning mechanism 27. The Z-axis drive mechanism 29 is composed of a linear motion mechanism such as a piezo element, for example, and reciprocates the objective lens 28 in the Z direction with a constant amplitude and a predetermined cycle. The Z-axis drive mechanism 29 is not limited to a piezo element, and any other linear actuator (linear motion mechanism) that linearly reciprocates the objective lens 28 such as a voice coil motor may be used. Good.

  The observation light from the sample 12 passes through the objective lens 28, is descanned by the X scanning mechanism 27 and the Y scanning mechanism 26, is further reflected by the dichroic mirror of the optical path dividing unit 25, and enters the photodetector 24.

  The photodetector 24 photoelectrically converts the incident observation light to convert the observation light into an electric signal having a value corresponding to the received light intensity, and supplies the electric signal to the sampling circuit 30. The sampling circuit 30 samples the electric signal supplied from the photodetector 24 at a predetermined timing and supplies the sampled electric signal to the imaging circuit 31. The imaging circuit 31 constructs an observation image from the electrical signal supplied from the sampling circuit 30 and outputs the observation image to a monitor (not shown) or a subsequent processing system.

  In addition, the timing control circuit 32 converts the reference clock into a clock having a predetermined frequency, thereby generating a read clock for reading data from the drive table held in the table holding unit 33 at a constant cycle.

  Here, for example, as shown in FIG. 7, the drive table is composed of drive data WD for controlling the operation of each part of the scanning microscope 11 at each time, and one drive data WD includes control data and output adjustment. Data, Y-axis drive data, and Z-axis drive data are included.

  The control data includes a value of a laser control signal for controlling turning on and off of the light source 22, and a value of a sampling valid signal indicating validity and invalidity of sampling of an electric signal for obtaining an observation image. The output adjustment data includes a value of an output adjustment signal for adjusting the amount of illumination light emitted from the light source 22, and the Y-axis drive data rotates the scanning mirror of the Y scanning mechanism 26. The value of the drive voltage of the rotational drive signal for this is included. Further, the Z-axis drive data includes the value of the drive voltage of the drive signal that drives the Z-axis drive mechanism 29.

  Returning to the description of FIG. 6, the timing control circuit 32 generates an address storing drive data to be read from the drive table in synchronization with the generated read clock, and supplies the address to the table holding unit 33. The table holding unit 33 reads the drive data stored at the address supplied from the timing control circuit 32, and the sampling circuit 30, the light source 22, the D / A (Digital / Analog) converter 34, the D / A converter 35, And supplied to the D / A converter 36.

  Specifically, the sampling valid signal and the laser control signal that constitute the control data of the drive data are supplied to the sampling circuit 30 and the light source 22, respectively. The output adjustment data, the Y-axis drive data, and the Z-axis drive data constituting the drive data are supplied to the D / A converter 34 to the D / A converter 36, respectively.

  When the drive cycle of the Z-axis drive mechanism 29 is designated, the arithmetic processing unit 37 calculates the overall cycle Zt of the drive signal, the standby time t, and the like. In addition, when the period Zt and the standby time t are calculated, the table generation unit 37 a provided in the arithmetic processing unit 37 generates a drive table based on the calculation results and records the drive table in the table holding unit 33.

  In addition, the timing control circuit 32 generates a sampling clock indicating the sampling timing of the electric signal output from the photodetector 24 based on the reference clock, and supplies the sampling clock 30 with the sampling clock. This sampling clock has a fixed time relationship with the read clock, and the sampling circuit 30 samples the electrical signal in synchronization with the sampling clock.

  The D / A converter 34 converts the output adjustment data supplied from the table holding unit 33 from a digital signal to an analog signal and supplies it to the output adjustment circuit 38. The output adjustment circuit 38 adjusts the amount of illumination light emitted from the light source 22 according to the output adjustment data from the D / A converter 34.

  The D / A converter 35 converts the Y-axis drive data supplied from the table holding unit 33 from a digital signal to an analog signal and supplies the analog signal to the Y-axis drive circuit 39. The Y-axis drive circuit 39 operates the Y scanning mechanism 26 according to the Y-axis drive data from the D / A converter 35.

  The D / A converter 36 converts the Z-axis drive data supplied from the table holding unit 33 from a digital signal to an analog signal and supplies the analog signal to the Z-axis drive circuit 40. The Z-axis drive circuit 40 operates the Z-axis drive mechanism 29 according to the Z-axis drive data from the D / A converter 36 to move the objective lens 28 in the Z direction.

  The X-axis drive circuit 41 operates the X scanning mechanism 27 in accordance with the supplied X-axis drive data. The Z position detection circuit 42 acquires information indicating the position of the objective lens 28 in the Z direction from the Z axis drive mechanism 29 and supplies the information to the arithmetic processing unit 37. The arithmetic processing unit 37 appropriately controls the operation of the scanning microscope 11 based on the information indicating the position in the Z direction of the objective lens 28 supplied from the Z position detection circuit 42.

[Description of drive table generation processing]
By using the scanning microscope 11, the user can repeatedly observe a plurality of observation surfaces arranged in the Z direction of the sample 12 at a predetermined cycle, with the surface of the sample 12 perpendicular to the Z direction as an observation surface. At this time, the user designates a period for reciprocating the Z-axis drive mechanism 29 in the Z direction according to the observation period of the plurality of observation surfaces to be observed, and instructs generation of a drive table.

  When the generation of the drive table is instructed by the user, the scanning microscope 11 starts the drive table generation process according to the user's instruction, and generates the drive table. Hereinafter, the drive table generation processing by the scanning microscope 11 will be described with reference to the flowchart of FIG.

  In step S <b> 11, the arithmetic processing unit 37 drives the Z-axis drive mechanism 29 based on a cycle for reciprocally driving the Z-axis drive mechanism 29 specified by the user in the Z direction, that is, the drive cycle of the Z-axis drive mechanism 29. The entire period Zt of the drive signal is calculated.

  In step S12, the arithmetic processing unit 37 calculates the standby time t based on the cycle Zt of the drive signal and the function V (t) recorded in advance.

  For example, the function V (t) = f (t) + g (t) and the decrease function f (t) = − kt + 1, the increase function g (t) = A (k) · cos (π / 2− (πt / 2Zt)), the arithmetic processing unit 37 substitutes the coefficient k determined by the cycle Zt into the function V (t). Then, the arithmetic processing unit 37 calculates t (where 0 ≦ t ≦ Zt) where the function V (t) obtained as a result becomes the maximum as the standby time t.

  The standby time t obtained in this way is a time represented by the product of the delay time D and the coefficient k in FIG. Here, the delay time D is a delay time composed of a response delay that occurs in the Z-axis drive mechanism 29 when the period of the cosine wave component of the drive signal is Zt, and a delay that occurs due to an action such as a dynamic friction coefficient and inertia. is there.

  Note that the delay time D may be obtained in advance for each cycle Zt and recorded in a table. In such a case, the arithmetic processing unit 37 obtains the delay time D associated with the designated cycle Zt from the table, and obtains the product of the coefficient k and the delay time D, whereby the standby time t = k XD is calculated.

  In step S <b> 13, the arithmetic processing unit 37 subtracts the standby time t from the cycle Zt of the entire drive signal to calculate the cycle Zc = Zt−t of the cosine wave component of the drive signal.

  In step S14, the table generation unit 37a generates drive data for the cosine wave component portion of the drive signal.

  For example, if the drive table read cycle is Tb, drive data is read M = Zc / Tb times during the period of the cosine wave component cycle Zc in one cycle of the drive signal. Therefore, the table generation unit 37a calculates the drive voltage T (n) = cos (2nπ / M) of the drive signal at each time n (where 0 ≦ n ≦ M−1) based on the cycle Zc and the cycle Tb. To do.

  Then, the table generating unit 37a uses the calculated drive voltage T (n) at each time n as the Z-axis drive data constituting the drive data at the time n. As a result, the drive signal from time n = 0 to time n = M−1 becomes a cosine wave having a cycle Zc.

  The table generation unit 37a generates control data, output adjustment data, and Y-axis drive data at each time n (where 0 ≦ n ≦ M−1) by referring to various types of information designated by the user. Then, drive data at each time is generated from these data and the Z-axis drive data.

  The table generation unit 37a supplies the drive data at each time n (where 0 ≦ n ≦ M−1) obtained in this way to the table holding unit 33 and records the drive data in the drive table.

  In step S15, the table generation unit 37a generates drive data for a pause period portion of the drive signal.

  For example, when the read cycle of the drive table is Tb, drive data is read Q = Zt / Tb times during the period of one cycle Zt of the drive signal. Since the drive data is read M times during the period Zc of the cosine wave component in the period Zt, the drive data is read L = Q−M times during the remaining waiting time t. .

  Therefore, the table generation unit 37a sets the drive voltage T (n) of the drive signal at each time n (where M ≦ n ≦ M + L−1) in the pause period as T (n) = cos (2π). Then, the table generation unit 37a sets the drive voltage T (n) = cos (2π) as the Z-axis drive data constituting the drive data at time n (where M ≦ n ≦ M + L−1). As a result, the drive signal from time n = M to time n = M + L−1 becomes a signal of a constant drive voltage.

  The table generation unit 37a generates control data, output adjustment data, and Y-axis drive data at each time n (where M ≦ n ≦ M + L−1) with reference to various types of information designated by the user. Then, drive data at each time is generated from these data and the Z-axis drive data.

  The table generation unit 37a supplies the drive data at each time n (where M ≦ n ≦ M + L−1) obtained in this way to the table holding unit 33 and records it in the drive table. As described above, when the drive table including the drive data for one cycle of the drive signal is generated, the drive table generation process ends. When observing the sample 12, each drive data constituting a drive table for one cycle is repeatedly read and used in order.

  After the drive table generation process described above is performed and the drive table is recorded in the table holding unit 33, when the user operates the scanning microscope 11 to instruct fluorescence observation of the sample 12, the scanning microscope 11 Starts the observation process in response to a user instruction. Hereinafter, the observation process by the scanning microscope 11 will be described with reference to the flowchart of FIG.

  In step S41, the table holding unit 33 reads the drive table. That is, the table holding unit 33 reads the drive data from the address supplied from the timing control circuit 32 and supplies each data constituting the drive data to each unit of the scanning microscope 11.

  Specifically, the sampling valid signal and the laser control signal constituting the control data are supplied to the sampling circuit 30 and the light source 22, respectively, and the output adjustment data is supplied to the D / A converter 34. Further, the Y-axis drive data is supplied to the D / A converter 35, and the Z-axis drive data is supplied to the D / A converter 36.

  The D / A converter 34 to D / A converter 36 convert the output adjustment data, Y-axis drive data, and Z-axis drive data supplied from the table holding unit 33 from digital signals to analog signals, and output adjustment circuits 38 to This is supplied to the Z-axis drive circuit 40.

  In step S42, the output adjustment circuit 38 adjusts the output of the illumination light output from the light source 22 based on the output adjustment data supplied from the D / A converter 34.

  The light source 22 emits illumination light according to the laser control signal supplied from the table holding unit 33. That is, if the laser control signal is turned on, the illumination light is emitted. If the laser control signal is turned off, the illumination light is not emitted. At this time, the light source 22 adjusts the amount of illumination light emitted according to the control of the output adjustment circuit 38. When illumination light is emitted from the light source 22, the illumination light is irradiated to the sample 12 through the optical system 23.

  In step S43, the Y scanning mechanism 26 rotates the scanning mirror. That is, the Y-axis drive circuit 39 operates the Y-scanning mechanism 26 based on the Y-axis drive data supplied from the D / A converter 35, and the Y-scanning mechanism 26 follows the control of the Y-axis drive circuit 39. Rotate the scanning mirror.

  The X scanning mechanism 27 also rotates the scanning mirror according to the control of the X axis drive circuit 41. Thereby, the illumination light is deflected by the scanning mirrors of the Y scanning mechanism 26 and the X scanning mechanism 27, and the observation surface of the sample 12 is scanned with the illumination light.

  In step S44, the Z-axis drive mechanism 29 moves the objective lens 28 in the Z direction. Specifically, the Z-axis drive circuit 40 drives the Z-axis drive mechanism 29 based on the Z-axis drive data supplied from the D / A converter 36, that is, the drive voltage of the drive signal, and sets the objective at a position determined by the drive voltage. The lens 28 is moved. Thereby, the illumination light is condensed on the desired observation surface of the sample 12.

  When the sample 12 is irradiated with illumination light, observation light is emitted from the sample 12, and the observation light passes through the optical system 23 and is received by the photodetector 24. The photodetector 24 photoelectrically converts the incident observation light and supplies the electric signal obtained as a result to the sampling circuit 30.

  In step S45, the sampling circuit 30 determines whether or not to sample the electrical signal. For example, the sampling circuit 30 indicates that the sampling clock supplied from the timing control circuit 32 is a timing at which sampling is to be performed, and a sampling valid signal indicating that it is valid is supplied from the table holding unit 33. If it is determined that sampling is to be performed.

  If it is determined in step S45 that sampling is not performed, the process of step S46 is skipped, and the process proceeds to step S47.

  On the other hand, if it is determined in step S45 that sampling is to be performed, in step S46, the sampling circuit 30 samples the electrical signal from the photodetector 24, converts the electrical signal from an analog signal to a digital signal, and forms an image. Supply to the circuit 31.

  The imaging circuit 31 accumulates the electrical signals supplied from the sampling circuit 30 for the required number of pixels, generates an observation image, and outputs the observation image to a monitor or the like. Thereby, for example, an observation image is displayed on the monitor, and the user can observe the sample 12.

  If it is determined in step S46 that sampling has been performed, or if it is determined in step S45 that sampling is not performed, in step S47, the scanning microscope 11 determines whether or not to end the process. For example, when the end of observation is instructed by the user, it is determined to end the process.

  If it is determined in step S47 that the process is not terminated, the process returns to step S41, and the above-described process is repeated. That is, the next drive data is read from the drive table, and the sample 12 is observed.

  On the other hand, when it is determined in step S47 that the process is to be terminated, each part of the scanning microscope 11 stops the process being performed, and the observation process is terminated.

  As described above, the scanning microscope 11 performs fluorescence observation of the sample 12 according to the drive table. When the Z-axis drive mechanism 29 is driven at a high speed by driving the Z-axis drive mechanism 29 using the signal with the optimum standby time inserted in the cosine wave as a drive signal when observing the sample 12, the cycle of the drive signal The decrease in the drive amplitude can be reduced without changing.

  In the above description, the relative distance in the Z direction between the objective lens 28 and the stage 21 (sample 12) is changed by moving the objective lens 28. However, the stage 21 is moved by the Z-axis drive mechanism 29. May be moved.

  The embodiments of the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

  11 scanning microscope, 21 stage, 26 Y scanning mechanism, 28 objective lens, 29 Z-axis drive mechanism, 33 table holding unit, 37 arithmetic processing unit, 37a table generating unit

The microscope of the present invention generates a linear motion mechanism that changes a distance between a stage on which a sample to be observed is placed and an objective lens in the optical axis direction of the objective lens, and a drive signal that drives the linear motion mechanism. Drive signal generating means for supplying the drive signal to the linear motion mechanism and driving control means for driving the linear motion mechanism, wherein the drive signal is for driving the linear motion mechanism relative to the drive signal. A waveform having a first period shorter than the delay time, wherein each period waveform is composed of one period of a cosine wave having a second period shorter than the first period and a section in which the value is constant. Features.

Claims (4)

A linear motion mechanism that changes the distance between the stage on which the sample to be observed is placed and the objective lens in the direction of the optical axis of the objective lens;
A first period of a cosine wave as the drive signal for reciprocally driving the linear motion mechanism with a constant amplitude and with a period shorter than a drive delay time of the linear motion mechanism with respect to a drive signal for driving the linear motion mechanism Calculating means for subtracting a predetermined time from the cosine wave of the second period;
Drive signal generating means for generating a final drive signal having a cycle of the first cycle by inserting a pause interval having a constant value into a part of the cosine wave of the second cycle;
A microscope comprising: drive control means for supplying the final drive signal to the linear motion mechanism and driving the linear motion mechanism to reciprocate. The drive signal generation means has a length of the predetermined time, with one portion of the waveform of the cosine wave of the second cycle having a change rate of the cosine wave being zero as an insertion portion. The microscope according to claim 1, wherein the final drive signal is generated by inserting the pause section having the same value as the value of the insertion portion of the cosine wave into the insertion portion. The microscope according to claim 1, wherein the predetermined time is shorter than a delay time for driving the linear motion mechanism. The calculation means indicates an increase rate of the maximum value of the amplitude of the reciprocating drive when the period of the drive signal is changed from the first period to a predetermined period when the drive signal is a cosine wave. The sum of the first function and the second function indicating the increase rate of the maximum value of the amplitude of the reciprocating drive that is increased by the pause period when the length of the pause period to be inserted into the drive signal is changed. The microscope according to any one of claims 1 to 3, wherein the predetermined time is calculated by calculating a maximum value of a function obtained by the calculation.

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