JPH06137813A - Laser scanning type high speed displacement measuring method and its device - Google Patents

Abstract

PURPOSE:To determine the change of objective time of a measurement object by exciting a viscous elastic measurement object at a fixed frequency, detecting the displacement of the fixed part of the object from the change of the strength of a scanning laser light, and reconstructing the detected displacement on the exciting signal of the measurement object taken as a time reference. CONSTITUTION:A measurement object 1 has viscous elasticity, and is fixed to a holder 3 at one end, and when its another end is excited by an actuator 2 driven by an exciting signal source 11, follows the excitation with phase lag caused by the viscous elasticity. A scanning laser light issued from an Ar laser 4 detects a detection point 7, and a detection signal issued from a photomultiplier tube 10 enters a controller 12. A synchronous signal issued from a signal source 11 also enters the controller 12 at the same time. The primary scanning of a galvanic mirror is continuously carried out, and the primary image of the object 1 and a signal issued from the signal source 11 are simultaneously taken in the controller 12 at each scanning position to compute a time when the displacement is obtained to the synchronous signal serving as a time reference for computing the dispacement of the object 1 from the laser scanning position. This process is repeated at every scanning action to determine the displacement of the object 1 speedily and precisely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser scanning type displacement measuring method and device capable of measuring a displacement at a high speed when an external force varying with time is applied to a viscoelastic measuring object such as a living cell. Is.

[0002]

2. Description of the Related Art Conventionally, when a time-varying external force is applied to a viscoelastic measuring object, such as a living cell, each part of the cell follows the changing external force with a phase delay. Such measurement of displacement of the measurement object is important for clarifying the behavior of living cells, etc., and many photographs have been taken using a conventional optical microscope, and these changes are observed to determine the temporal change of displacement. It was done by asking.

[0003]

However, in the conventional method, since the observation is performed while taking photographs one by one, it takes a very long time to measure and it is difficult to continuously obtain the displacement amount. There was also a problem in terms of measurement accuracy.

The present invention is intended to solve the above problems.
An object of the present invention is to provide a laser scanning type displacement measuring method and a measuring device capable of measuring deformation or displacement of a measuring object having viscoelasticity due to an external force using a scanning laser beam at high speed and continuously with high accuracy. .

[0005]

A laser scanning high-speed displacement measuring method of the present invention irradiates a scanning laser spot in a state where a viscoelasticity measurement target is mechanically excited at a predetermined cycle and irradiates a predetermined portion of the measurement target. The change in the intensity of the transmitted or reflected light of the laser light is detected, the displacement of the predetermined portion is detected by the displacement of the irradiation laser light when the detection signal is obtained, and the detected displacement is the excitation signal of the measurement object over time. It is characterized in that it is reconstructed as a reference to obtain the displacement with time of the measurement target.

The laser scanning high-speed displacement measuring device of the present invention is driven by an excitation signal source to scan an actuator for exciting a viscoelasticity measurement target, and a laser beam for scanning at a period synchronized with the excitation signal to measure the measurement target. An optical system for irradiating a laser beam, a detector for detecting a displacement signal of the measurement target from changes in transmitted light or reflected light from the measurement target, and a detection signal from the detector and a synchronization signal obtained from the excitation signal, And a controller for reconstructing the displacement with respect to time of the measuring object by giving a time reference to the displacement signal.

[0007]

The present invention excites a viscoelasticity measurement object at a predetermined cycle,
The measurement target is irradiated with laser light that is scanned in synchronization with this, and the photomultiplier detects changes in the intensity of the transmitted or reflected light of the scanning laser light at the point of interest of the measurement target, and the laser light scanning position at the detection timing. The displacement of the point of interest of the measurement object is obtained by using the excitation signal as the time reference, and the displacement signal of the measurement object is obtained by purely electrical processing using the excitation signal as the time reference. Since it can be reconstructed, it becomes possible to obtain the displacement of the viscoelasticity measurement target at high speed and with high accuracy.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing the construction of a laser scanning high-speed displacement measuring device of the present invention, and FIGS. 2, 3 and 4 are diagrams for explaining the displacement measuring principle of the present invention. In the figure, 1 is an object to be measured, 2 is a PZT actuator, 3 is a holder, and 4 is Ar.
A laser, 5 is a galvanometer mirror, 6 is an objective lens, 7 is a detection point, 8 is an imaging lens, 9 is a mirror, 10 is a photomultiplier, 11 is an excitation signal source, and 12 is a controller.

The object 1 to be measured has viscoelasticity like cells of a living body, one end of which is fixed by a holder 3 and the other end of which is mechanically excited by a PZT actuator 2 driven by an excitation signal source 11. Sometimes, a specific detection point 7 inside the measurement target 1 follows the displacement of the actuator, but a phase delay occurs due to viscoelasticity. It can be schematically considered as a model in which the mass of this detection point is m, and the holder 3 and the actuator 2 are connected by the spring constants k1 and k2, and the natural frequency f at this time is f = (1 / 2π) {(k1 + k2) / m} ^1/2 . As described above, the laser beam from the Ar laser 4 is reflected by the galvano mirror 5 with respect to the measurement target excited by the actuator 2, and is condensed by the objective lens 6 to be condensed at the detection point 7. The reflected light is imaged on the photomultiplier 10 via the mirror 9 by the imaging lens 8 and detected.

The actuator 2 is excited by an excitation signal source 11 that generates a signal such as a sawtooth wave or a sine wave, and a galvanomirror 5 that deflects the light from the Ar laser 4 is synchronized with the signal from the excitation signal source 11. The laser light from the Ar laser 4 is scanned to irradiate the measuring object 1.

From the photomultiplier 10, a detection point 7
A specific detection point is detected as a change in the transmitted light of the laser light or a change in the reflected light, and is captured as one signal of the controller 12. At the same time, the synchronization signal from the excitation signal source 11 is taken in as a time reference signal.

Assuming that the end point of the object 1 to be measured is the detection point 7 and the laser light is focused through the objective lens 6 as shown in FIG. 2, the signal detected by the photomultiplier 10 is For example, as shown in FIG. 3A, the transmitted light intensity decreases on the measurement target 1 side,
On the opposite side, the transmitted light intensity increases. Therefore, the threshold level is set, and the detection point 7 is detected when the detection signal strength crosses the threshold level. When the synchronization signal corresponding to the signal exciting the measurement target 1 has a waveform as shown in FIG. 3B, the laser beam is scanned in synchronization with the synchronization signal. The scan position is known in time.

Now, assuming that the detection signal intensity changes at time t0 and the detection point 7 is detected by the photomultiplier 10, as shown in FIG. 3 (c), the displacement d of the spot of the scanning laser light with respect to time t0. Is known, so
This is obtained as the displacement of the detection point 7. Therefore, FIG.
As shown in (a) and (b), when a specific displacement y0 is given, the time reference obtained from the synchronization signal is t0,
Assuming that the time reference when a specific displacement y1 is given is t1, as shown in FIG. 5, it is possible to plot the displacement of the detection point corresponding to each time, and sequentially plot y2, y3 .... When scanning is performed, the displacement of the detection point is obtained with the synchronization signal as a time reference.

Therefore, in FIG. 1, the synchronization signal obtained from the excitation signal 11 and the detection signal obtained from the photomultiplier 10 can be taken into the controller 12, and the displacement of the measuring object can be reconstructed with the synchronization signal as a time reference. it can. That is, the one-dimensional scanning of the galvanometer mirror is continuously performed, and at this time, the one-dimensional image of the measuring object and the signal of the excitation signal source are simultaneously taken into the controller 12 for each scanning position, and the synchronization signal which is the time reference The time when the displacement is obtained is calculated, and the displacement of the measurement target may be obtained from the laser scanning position. By repeating such calculation for all the scans, a displacement curve with respect to time as shown in FIG. 5 is obtained, and it becomes possible to obtain the displacement of the viscoelasticity measurement object at high speed and continuously with high accuracy.

[0015]

As described above, according to the present invention, since it is possible to obtain the displacement of the viscoelasticity measurement object by purely electrical processing, it is possible to perform the displacement measurement at high speed and continuously with high accuracy. It will be possible.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a configuration of a laser scanning high-speed displacement measuring device of the present invention.

FIG. 2 is a diagram for explaining the displacement measurement principle of the present invention.

FIG. 3 is a diagram for explaining the displacement measurement principle of the present invention.

FIG. 4 is a diagram for explaining the displacement measurement principle of the present invention.

FIG. 5 is a diagram showing a displacement characteristic with respect to time of a measurement target.

[Explanation of symbols]

1 ... Object to be measured, 2 ... PZT actuator, 3 ... Holder, 4 ... Ar laser, 5 ... Galvano mirror, 6 ... Objective lens, 7 ... Detection point, 8 ... Imaging lens, 9 ... Mirror, 10
... Photomultiplier, 11 ... Excitation signal source, 12 ... Controller.

Claims (2)

[Claims] 1. A viscoelasticity measurement target is irradiated with a scanning laser spot while being mechanically excited in a predetermined cycle, and a change in intensity of transmitted light or reflected light of the irradiation laser light by a predetermined portion of the measurement target is detected. The displacement of the predetermined portion is detected by the displacement of the irradiation laser light when the detection signal is obtained, and the displacement is detected with respect to time by reconstructing the detected displacement with the excitation signal of the measurement target as the time reference. Characteristic laser scanning high-speed displacement measurement method. 2. An actuator driven by an excitation signal source to excite a viscoelasticity measurement target, an optical system for scanning a laser beam with a period synchronized with the excitation signal, and irradiating the measurement target with the laser beam, and The detector that detects the displacement signal of the measurement target from the change in the transmitted light or the reflected light and the synchronization signal obtained from the detection signal and the excitation signal from the detector give a time reference to the displacement signal and A laser scanning high-speed displacement measuring device having a controller for reconstructing temporal displacement.