JP5075722B2 - Scanning laser microscope - Google Patents

Description

  The present invention relates to a technique of a microscope, and more particularly to a technique of a scanning laser microscope.

  A scanning laser microscope is known as an apparatus for measuring a three-dimensional shape in a non-contact manner. In this apparatus, the surface of the object to be scanned is two-dimensionally scanned at high speed with a laser beam condensed at one point by the objective lens, and the reflected light is arranged at a position optically conjugate with the focal position of the objective lens. Light is received through the confocal stop. If the confocal stop is placed at this position, the reflected light received is only for the portion of the surface that is in focus with the objective lens. Only the focus area can be observed.

  By using this principle, the value of the relative distance Z between the objective lens and the test object when the luminance value of each pixel constituting the reflected light image (luminance image) is maximized is determined for each pixel. The height shape measurement of the entire surface of the test object can be performed. Further, if an image is formed with the maximum luminance value of each pixel at this time, it is possible to obtain an omnifocal image in which the surface of the test object is in focus throughout.

  By the way, the scanning laser microscope illuminates one point on the test object at a certain moment, and the reflected light from the one point is acquired by the light receiving element. In a normal scanning laser microscope, for example, data of 1024 × 1024 pixels corresponding to one image size is acquired for several to several tens of images per second. Therefore, for example, when acquiring 1024 × 1024 = 1M pixels per second, it is necessary for the light receiving element to perform data sampling of 1M points × 5, that is, 5M points per second. In order to transmit such high-speed data, the light receiving system of the scanning laser microscope corresponds to a frequency bandwidth of about several M to several tens of MHz (hereinafter referred to as “sensor bandwidth”). Response speed is required. If the sensor bandwidth is not sufficiently secured, the contrast of the obtained image is lowered. That is, when the response of the light receiving system cannot catch up with the sampling speed of the light receiving element, the resolving power in the XY direction (the direction on the plane perpendicular to the direction of the relative distance Z) in the image is deteriorated.

  On the other hand, in the above-described height shape measurement, in order to increase the detection accuracy, it is required to increase the S / N ratio (signal-to-noise ratio) of the light receiving system. For this purpose, it is preferable to reduce the sensor bandwidth described above. That is, if the sensor bandwidth is narrowed, the S / N ratio of the light receiving system is improved and the height measurement accuracy is improved.

  Thus, the S / N ratio of the light receiving system is in a trade-off relationship with the resolving power. That is, when the sensor bandwidth is widened, the resolution in the XY directions does not deteriorate, but the high-frequency component of random noise cannot be limited, so the S / N ratio decreases. Conversely, when the sensor bandwidth is narrowed, the S / N ratio is increased and the height measurement accuracy is improved, but the resolving power in the XY directions is deteriorated.

  In order to achieve both the S / N ratio and the resolving power, a sufficient sensor bandwidth is secured so as not to degrade the resolving power, and a plurality of luminance images obtained at different times are integrated under the sensor bandwidth. In general, a technique for improving the S / N ratio is performed.

For example, in Patent Document 1, when the light of a small amount of light such as weak light is detected by changing the diameter of the confocal stop, the light is received by increasing the amount of light received by increasing the diameter of the confocal stop. A technique is disclosed in which the S / N ratio of the system is improved while the confocal aperture diameter is reduced to ensure the resolving power when the amount of light is large.
JP 2007-133419 A

  The purpose of use of the scanning laser microscope varies depending on the situation of use, such as when high resolution is required, or when high-precision height measurement is required and degradation of resolution is acceptable. However, in the present situation where the sensor bandwidth of the scanning laser microscope is unchanged as determined at the time of product design in view of the balance between the resolving power and the S / N ratio, dissatisfaction remains for either of the above-mentioned usage purposes. It can happen.

Here, as described above, the method of improving the S / N ratio by integrating the luminance images takes time to obtain a plurality of luminance images.
In addition, the technology disclosed in Patent Document 1 that makes the diameter of the confocal stop variable is that the diameter of the confocal stop that is usually about several tens to several hundreds of micrometers is maintained with high accuracy. Since it is difficult, the device becomes expensive. Also, when the confocal aperture diameter is increased, the amount of light incident on the light receiving system is increased and the S / N ratio is improved, but the sectioning effect (resolution in the height direction) of the confocal optical system is also reduced. The overall performance of height detection is not necessarily improved.

  The present invention has been made in view of the above-described problems, and a problem to be solved is to provide a scanning laser microscope that can meet both requirements of a high S / N ratio and a high resolution. It is.

  A scanning laser microscope, which is one aspect of the present invention, receives laser light that passes through an objective lens and a confocal stop when reflected on the surface of a sample while being scanned two-dimensionally. And changing the bandwidth of the light receiving system that determines the response speed from when the light receiving system receives the laser light until it outputs the light amount information of the laser light. Bandwidth changing means.

  The scanning laser microscope described above further includes operation mode selection instruction acquisition means for acquiring an instruction to select one of a plurality of operation modes set in advance for the scanning laser microscope. The changing unit can be configured to change the bandwidth of the light receiving system based on the operation mode related to the instruction acquired by the operation mode selection instruction acquiring unit.

  In the above-described scanning laser microscope, the light receiving system includes a photoelectric conversion element that receives the laser light and outputs an analog electric signal having a magnitude corresponding to the amount of the laser light. The information on the light quantity of the laser beam output from the signal is the analog electric signal, and the bandwidth changing means amplifies the analog electric signal, a plurality of analog signal amplifiers having different bandwidths, and the analog electric signal And an amplifier switching means for switching an analog signal amplifier used for amplification.

  In the above-described scanning laser microscope, the light receiving system includes a photoelectric conversion element that receives the laser light and outputs an analog electric signal having a magnitude corresponding to the amount of the laser light. The information on the amount of light of the laser beam output from is the analog electrical signal, and the bandwidth changing means determines the analog signal amplifier that amplifies the analog electrical signal and the bandwidth of the analog signal amplifier. Circuit constant changing means for changing the circuit constant of the analog signal amplifier.

  A scanning laser microscope, which is another aspect of the present invention, reflects laser light that passes through an objective lens and a confocal stop when reflected on the surface of a sample while being scanned two-dimensionally. It has a plurality of light receiving systems that receive light and output information on the amount of light, and the light receiving system determines a response speed from receiving the laser light to outputting information on the amount of light of the laser light. The bandwidth is different from each other.

  In the scanning laser microscope described above, an operation mode selection instruction acquisition means for acquiring an instruction to select one of a plurality of operation modes set in advance for the scanning laser microscope, and the operation mode selection instruction acquisition And a light amount information selecting unit that selects information on the light amount of the laser beam output from each of the plurality of light receiving systems based on an operation mode related to the instruction acquired by the unit.

  According to the present invention, it is possible to provide a scanning laser microscope capable of meeting both requirements for a high S / N ratio and a high resolving power as described above.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, FIG. 1 will be described. FIG. 1 shows a first example of the configuration of a scanning laser microscope embodying the present invention.

The scanning laser microscope includes a laser microscope main body 100, a computer 200, an instruction unit 300, and a display unit 400.
The laser microscope main body 100 includes a control unit 110, a laser light source 120, a beam splitter 130, an XY scanning mechanism 140, a plurality of objective lenses 150, an objective lens switching mechanism 160, a confocal stop 170, and a light receiving system 180. And a Z scanning mechanism 190.

The control unit 110 controls each component of the laser microscope main body 100 in accordance with an operation instruction sent from the computer 200.
The laser light source 120 excites and outputs laser light. The laser light output from the laser light source 120 passes through the beam splitter (BS) 130, passes through the XY scanning mechanism 140, and then passes through the objective lens 150 on the optical path to irradiate the surface of the measurement sample 10 that is a sample. Is done. Here, when the control unit 110 controls the XY scanning mechanism 140 in accordance with an operation instruction of the computer 200, the XY scanning mechanism 140 transmits the laser light on the surface of the measurement sample 10 in the XY direction (the light of the laser microscope main body 100). Two-dimensional scanning is performed in two directions perpendicular to the optical axis of the objective lens 150 on the road.

  Note that the control unit 110 controls the objective lens switching mechanism 160 in accordance with an operation instruction of the computer 200, so that the objective lens 150 on the optical path of the laser microscope main body 100 can be switched.

  The laser beam irradiated on the surface of the measurement sample 10 is reflected by the surface. The reflected laser light passes through the objective lens 150 and the XY scanning mechanism 140 on the optical path, and is then reflected by the beam splitter (BS) 130 and travels toward the confocal stop 170.

  The opening of the confocal stop 170 is disposed at a position optically conjugate with the focal position of the objective lens. Therefore, only the laser beam reflected from the surface of the measurement sample 10 that is reflected at the focal position of the objective lens 150 on the surface passes through the opening of the confocal stop 170 and reaches the light receiving system 180.

  The light receiving system 180 receives laser light that has passed through the confocal stop 170 and outputs information on the amount of light to the computer 200 as luminance information. The light receiving system 180 includes a light receiving element 181 and an amplifying unit 182, and details thereof will be described later.

  The Z scanning mechanism 190 is controlled by the control unit 110 according to the operation instruction of the computer 200, and moves the objective lens switching mechanism 160 up and down in the Z direction (the direction of the optical axis of the objective lens 150 on the optical path of the laser microscope main body 100). Thus, the relative distance Z between the objective lens 150 and the measurement sample 10 on the optical path is changed.

  The computer 200 gives various operation instructions to the control unit 110 of the laser microscope main body 100 and acquires luminance information received from the light receiving system 180. The computer 200 performs various control processes based on the luminance information obtained in this way. For example, the computer 200 uses the luminance information as the luminance value of each pixel acquired based on the scanning control signal in the two-dimensional scanning by the XY scanning mechanism 140, thereby generating a luminance image on the surface of the measurement sample 10. Do. Alternatively, the computer 200 controls the Z scanning mechanism 190 to change the relative distance Z between the objective lens 150 and the measurement sample 10, and the relative distance when the luminance value of each pixel constituting the luminance image becomes maximum. By obtaining the value of Z for each pixel, the measurement processing of the height shape of the entire surface of the measurement sample 10 is performed. Moreover, the process which produces | generates the omnifocal image of the measurement sample 10 is performed using the local maximum luminance value of each pixel at this time.

  The instruction unit 300 acquires various operation instructions from the user of the scanning laser microscope of FIG. 1 and notifies the computer 200, and is, for example, a character keyboard device or a mouse device. This operation instruction includes an instruction to select one of a plurality of operation modes set in advance for the scanning laser microscope of FIG.

  The display unit 400 displays various images of the measurement sample 10 created by the computer 200. Further, a GUI screen for identifying various instructions from the user acquired by the instruction unit 300 such as various setting screens related to the operation of the scanning laser microscope is displayed under the control of the computer 200.

  The computer 200 is a computer having a very standard configuration, that is, an arithmetic processing unit such as an MPU that controls the operation of the entire computer 200 by executing a control program, and the arithmetic processing unit uses it as a work memory as necessary. Various memories performed between the main memory, a storage device such as a hard disk device that stores and stores various programs and control data, and the laser microscope main body 100, the instruction unit 300, and the display unit 400 A computer having an interface unit for managing the exchange of data can be used.

  Note that the above-described processing performed by the computer 200 creates a control program for causing the computer 200 to perform these processing in advance and stores it in a storage device. The computer 200 can perform the above-described processing when the arithmetic processing device reads the control program from the storage device and executes it in accordance with a predetermined instruction acquired by the instruction unit 300.

  Next, FIG. 2 will be described. FIG. 2 shows a detailed configuration of the light receiving system 180 shown in FIG. As described above, the light receiving system 180 includes the light receiving element 181 and the amplifying unit 182.

  The light receiving element 181 is a photoelectric conversion element that receives laser light that has passed through the confocal stop 170 and outputs an analog electric signal having a magnitude corresponding to the amount of the laser light. Pliers). Instead of using the PMT as the light receiving element 181, a PD (photodiode), an APD (avalanche photodiode), or the like may be used.

The amplifying unit 182 includes an IV converting unit 183 and a bandwidth changing unit 184.
When the light receiving element 181 outputs a current signal (photocurrent) having a magnitude corresponding to the amount of received laser light, the IV converter (current-voltage converter) 183 receives the current signal by the load resistor R0. Is converted into a voltage signal. Note that the capacitor C0 connected in parallel with the load resistor R0 in FIG. 2 represents the stray capacitance existing in the light receiving element 181 itself or the electric wiring between the light receiving element 181 and the amplifying unit 182 as an equivalent circuit. . At this time, the pass bandwidth (hereinafter simply referred to as “bandwidth”) f0 of the IV conversion unit 183 is expressed by the following [Equation 1].

When the output impedance of the light receiving element 181 is ignored, as is apparent from the circuit of FIG. 2, when the load resistance R0 is increased, the voltage of the signal output from the IV conversion unit 183 increases. However, as is clear from the formula [1], if the load resistance R0 is increased, the bandwidth f0 of the IV conversion unit 183 becomes narrow. Therefore, the load resistance R0 has a sufficient sensor bandwidth in the light receiving system 180. The width is set to a value that can be secured and set to a fixed value.

  The bandwidth changing unit 184 includes an amplifier 185, and amplifies the voltage signal output from the IV conversion unit 183 to generate an output signal. This output signal is sent to the computer 200 as information (luminance information) on the amount of laser light received by the light receiving system 180. In the computer 200, the voltage value of the luminance information is converted into digital data and used by an A / D conversion unit (not shown) provided in the interface unit.

  The bandwidth changing unit 184 includes a low-pass filter whose bandwidth is variable, and changes the bandwidth of the light receiving system 180 by changing the bandwidth. The bandwidth of the light receiving system 180 determines the response speed of the light receiving system 180 from when the laser beam is received until the information of the received light amount is output.

Next, FIG. 3 will be described. FIG. 3 shows a first example of a detailed configuration of the bandwidth changing unit 184.
The bandwidth changing unit 184 shown in FIG. 3 includes a feedback resistor in a basic non-inverting amplifier including an operational amplifier (operational amplifier) 185-1 having a pair of differential inputs, a feedback resistor R1, and a ground resistor Rs. A capacitor C1 is connected in parallel to R1. Therefore, this non-inverting amplifier is band-limited by the capacitor C1.

  Here, the capacitor C1 has a variable capacity, and its value is controlled by the control unit 110 in accordance with an operation instruction of the computer 200. More specifically, for example, a switched capacitor is used as the capacitor C1, and the control unit 110 changes its capacitance by changing the frequency of the control pulse given to the switched capacitor.

  The bandwidth f1 of the bandwidth changing unit 184 shown in FIG. 3 is expressed by the following [Equation 2].

When the bandwidth changing unit 184 shown in FIG. 3 is used, the bandwidth f of the entire amplifying unit 182 is expressed by the following [Equation 3].

That is, the amplifying unit 182 can change the bandwidth f of the entire amplifying unit 182, that is, the bandwidth of the light receiving system 180 by changing the bandwidth f 1 of the bandwidth changing unit 184 provided therein.

  Therefore, when a high resolving power is required for the observation image of the measurement sample 10 acquired using the scanning laser microscope of FIG. 1, the user gives an instruction to the instruction unit 300 to widen the bandwidth of the light receiving system 180. Like that. When the computer 200 obtains this instruction from the instruction unit 300, the computer 200 gives a predetermined operation instruction to the control unit 110, and controls the bandwidth changing unit 184 shown in FIG. 3 to reduce the capacitance of the capacitor C1. The control unit 110 performs the process. Then, since the bandwidth of the light receiving system 180 is widened, the resolution of the observation image of the obtained measurement sample 10 is increased.

  On the other hand, when it is necessary to measure the height of the measurement sample 10 with high accuracy using the scanning laser microscope of FIG. 1, the user instructs the instruction unit 300 to narrow the bandwidth of the light receiving system 180. To give. When the computer 200 obtains this instruction from the instruction unit 300, the computer 200 gives a predetermined operation instruction to the control unit 110 to increase the capacity of the capacitor C1 in the bandwidth changing unit 184 shown in FIG. The control unit 110 performs the process. Then, since the bandwidth of the light receiving system 180 is narrowed and the S / N ratio is improved, the accuracy of the height measurement of the measurement sample 10 is increased.

Instead of directly giving the instruction described above to the instruction unit 300 by the user, the following may be performed.
That is, first, as the operation mode of the scanning laser microscope of FIG. 1 described above, a high-resolution priority mode for acquiring an observation image of the measurement sample 10 with high resolution, and a high-precision measurement of the height of the measurement sample 10 An accuracy measurement mode and the like are set in advance. Then, the user gives an instruction to select one of these operation modes (for example, an instruction by pressing a selection button or the like) to the instruction unit 300. At this time, when the computer 200 obtains this instruction from the instruction unit 300, if the selection content related to the instruction is the high resolution priority mode, the computer 200 gives a predetermined operation instruction to the control unit 110, In the bandwidth changing unit 184 shown in FIG. 3, the control unit 110 performs control to reduce the capacitance of the capacitor C1. In addition, when the computer 200 obtains this instruction from the instruction unit 300, if the selected content related to the instruction is the high-precision measurement mode, the computer 200 gives a predetermined operation instruction to the control unit 110, and FIG. A process for causing the control unit 110 to perform control to increase the capacitance of the capacitor C1 in the illustrated bandwidth changing unit 184 is performed.

  As described above, the bandwidth changing unit 184 may change the bandwidth of the light receiving system 180 based on the operation mode related to the instruction acquired by the instruction unit 300. By doing so, the operability of the scanning laser microscope is improved.

  As described above, according to the scanning laser microscope of FIG. 1, the sensor band and S / N characteristics of the light receiving system 180 can be easily changed. Therefore, it is possible to provide characteristics that meet the user's requirements, such as when high resolving power is required, or when height measurement with high accuracy is required and degradation of resolving power is acceptable. Further, since no mechanical operation is performed to change this characteristic, the apparatus can be configured in a small size, and the cost of the apparatus can be reduced.

  In the bandwidth changing unit 184 shown in FIG. 3, the value of the capacitor C <b> 1 is changed under the control of the control unit 110 as a circuit constant that determines the bandwidth of the non-inverting amplifier. Instead, the light receiving system 180 is configured such that the value of the feedback resistor R1 is changed by the control of the control unit 110 as a circuit constant that determines the bandwidth of the non-inverting amplifier while the capacitor C1 is a fixed value. The bandwidth may be changed. However, when the value of the feedback resistor R1 is changed, the amplification factor of the non-inverting amplifier also changes. In this case, the value of the grounding resistor Rs is also changed in parallel, so that the non-inverting amplifier is changed. The change in the degree of amplification is suppressed.

Next, FIG. 4 will be described. FIG. 4 shows a second example of the detailed configuration of the bandwidth changing unit 184.
4 includes a capacitor Ca in parallel with a feedback resistor Ra in a basic non-inverting amplifier including an operational amplifier 185a having a pair of differential inputs, a feedback resistor Ra, and a ground resistor Rs. A capacitor Cb is in parallel with a feedback resistor Rb in a basic non-inverting amplifier composed of a first amplifier connected and an operational amplifier 185b having a pair of differential inputs, a feedback resistor Rb, and a ground resistor Rs. A capacitor Cc is connected to a feedback resistor Rc in a basic non-inverting amplifier composed of a second amplifier configured to be connected, an operational amplifier 185c having a pair of differential inputs, a feedback resistor Rc, and a ground resistor Rs. Amplifier connected in parallel, and signal selection It is configured to include a road 186.

  Here, the bandwidths fa, fb, and fc of the first amplifier, the second amplifier, and the third amplifier, which are analog signal amplifiers, are the values of the capacitor C1 in the above-described [Equation 2], respectively, Ca, Cb, And Cc, and the value of the feedback resistor R1 in this equation can be obtained by replacing with Ra, Rb, and Rc, respectively. In the present embodiment, this value is set to the resistance Ra = Rb = Rc, and the capacitors Ca, Cb, and Cc are set to different values that satisfy Ca <Cb <Cc. The bandwidths fa, fb, and fc of a certain first amplifier, second amplifier, and third amplifier are different from each other (fa> fb> fc).

  The signal selection circuit 186 receives output signals a, b, and c of the first amplifier, the second amplifier, and the third amplifier, respectively. The signal selection circuit 186 is, for example, a relay circuit, and any one of the output signals a, b, and c is selected by the control of the control unit 110 according to the operation instruction of the computer 200 and is selected. And output as the output of the bandwidth changing unit 184 (that is, the output of the light receiving system 180).

  As described above, in the configuration of FIG. 4, the signal selection circuit 186 amplifies the voltage signal output from the IV conversion unit 183 (that is, an analog electrical signal indicating the amount of laser light received by the light receiving element 181). When the amplifier used in the above is switched among three amplifiers of the first amplifier, the second amplifier, and the third amplifier having different bandwidths, the bandwidth of the light receiving system 180 is changed.

  Therefore, when a high resolving power is required for the observation image of the measurement sample 10 acquired using the scanning laser microscope of FIG. 1, the user gives an instruction to the instruction unit 300 to widen the bandwidth of the light receiving system 180. Like that. When the computer 200 acquires this instruction from the instruction unit 300, the computer 200 gives a predetermined operation instruction to the control unit 110, and uses the output signal a in the bandwidth changing unit 184 shown in FIG. A process for causing the control unit 110 to perform control to be selected is performed. Then, since the bandwidth of the light receiving system 180 is widened, the resolution of the observation image of the obtained measurement sample 10 is increased.

  On the other hand, when it is necessary to measure the height of the measurement sample 10 with high accuracy using the scanning laser microscope of FIG. 1, the user instructs the instruction unit 300 to narrow the bandwidth of the light receiving system 180. To give. Then, when the computer 200 acquires this instruction from the instruction unit 300, the computer 200 gives a predetermined operation instruction to the control unit 110, and the output signal c in the bandwidth changing unit 184 shown in FIG. A process for causing the control unit 110 to perform control to be selected is performed. Then, since the bandwidth of the light receiving system 180 is narrowed and the S / N ratio is improved, the accuracy of the height measurement of the measurement sample 10 is increased.

  Of course, as described above, the bandwidth changing unit 184 changes the bandwidth of the light receiving system 180 based on the operation mode (high resolution priority mode or high accuracy measurement mode) related to the instruction acquired by the instruction unit 300. Thus, the operability of the scanning laser microscope may be improved.

  As described above, when the configuration of FIG. 4 is adopted as the bandwidth changing unit 184, the circuit Ca is improved with respect to the configuration of FIG. 3 because capacitors Ca, Cb, and Cc having fixed capacitance values are used. In addition, noise generated by the circuit itself is also reduced.

  In the configuration of FIG. 4, the signal selection circuit 186 selects and uses one of three amplifiers having different bandwidths. Instead, two amplifiers having different bandwidths are used. One or four or more amplifiers having different bandwidths may be selected and used by the signal selection circuit 186.

Next, FIG. 5 will be described. FIG. 5 shows a second example of the configuration of a scanning laser microscope for carrying out the present invention.
In FIG. 5, the same components as those in the first example shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

  In the configuration shown in FIG. 5, the confocal stop 170 and the light receiving system 180 are deleted from the configuration shown in FIG. 1. Instead, the beam splitter 501, the first confocal stop 510 and the first light receiving system 511 are removed. And a second confocal stop 520 and a second light receiving system 521.

  The laser light output from the laser light source 120 passes through the beam splitter (BS) 130, passes through the XY scanning mechanism 140, and then passes through the objective lens 150 on the optical path to irradiate the surface of the measurement sample 10 that is a sample. Is done. Here, when the control unit 110 controls the XY scanning mechanism 140 in accordance with an operation instruction of the computer 200, the XY scanning mechanism 140 transmits the laser light on the surface of the measurement sample 10 in the XY direction (the light of the laser microscope main body 100). Two-dimensional scanning is performed in two directions perpendicular to the optical axis of the objective lens 150 on the road.

  The laser beam irradiated on the surface of the measurement sample 10 is reflected by the surface. The reflected laser light passes through the objective lens 150 and the XY scanning mechanism 140 on the optical path, and is then reflected by the beam splitter (BS) 130 toward the beam splitter 501.

  A beam splitter (BS) 501 bisects the laser light coming from the beam splitter 130. Then, 50% of the light is transmitted and directed to the first confocal stop 510, and the remaining 50% is reflected and directed to the second confocal stop 510.

  The opening of the first confocal stop 510 is disposed at a position optically conjugate with the focal position of the objective lens 150 on the optical path. Accordingly, only the laser light reflected from the surface of the measurement sample 10 that is reflected at the focal position of the objective lens 150 on the surface passes through the opening of the first confocal stop 510 and passes through the first light receiving system. 511.

  The first light receiving system 511 receives laser light that has passed through the first confocal stop 510 and outputs information on the amount of light to the computer 200 as first luminance information. The first light receiving system 511 includes a first light receiving element 512 and an amplifying unit 513.

  The opening of the second confocal stop 520 is an optically conjugate position with respect to the focal position of the objective lens 150 on the optical path, and is arranged at a position different from the first confocal stop 510. ing. Accordingly, only the laser beam reflected from the surface of the measurement sample 10 that has been reflected at the focal position of the objective lens 150 on the surface passes through the opening of the second confocal stop 520 and passes through the second light receiving system. 521.

  The second light receiving system 521 receives the laser light that has passed through the second confocal stop 520 and outputs information on the amount of light to the computer 200 as second luminance information. The second light receiving system 521 includes a second light receiving element 522 and an amplifying unit 523.

  Next, FIG. 6 will be described. FIG. 6 shows a detailed configuration of the first light receiving system 511 and the second light receiving system 521 shown in FIG. In the present embodiment, the first light receiving system 511 and the second light receiving system 521 have the same configuration, and the first light receiving element 512, the second light receiving element 522, and the first amplifying unit 513, respectively. And a second amplifying unit 523.

  The first light receiving element 512 and the second light receiving element 522 have the same configuration as the light receiving element 181 in the configuration shown in FIG. That is, the first light receiving element 512 and the second light receiving element 522 are photoelectric conversion elements that receive incoming laser light and output an analog electric signal having a magnitude corresponding to the amount of the laser light. PMT (photomultiplier). Here, instead of using the PMT, a PD (photodiode), an APD (avalanche photodiode), or the like may be used.

The first amplifying unit 513 and the second amplifying unit 523 are configured to include an IV conversion unit 183 and a bandwidth limiting amplifier 530 having the same configuration as that shown in FIG. .
In the bandwidth limiting amplifier 530, a capacitor C2 is connected in parallel to a feedback resistor R2 in a basic non-inverting amplifier composed of an operational amplifier 185-2 having a pair of differential inputs, a feedback resistor R2, and a ground resistor Rs. Configured. However, the value of the capacitor C2 is different between the first amplifying unit 513 and the second amplifying unit 523.

  The bandwidth f of each of the first amplifying unit 513 and the second amplifying unit 523 replaces the value of the capacitor C1 in the above equation [2] with C2, and also replaces the value of the feedback resistor R1 in this equation with R2. Can be obtained. Here, since the values of the capacitors C2 are different from each other, the bandwidths of the first amplification unit 513 and the second amplification unit 523 are different from each other. Accordingly, the first light receiving system 511 and the second light receiving system 521 have different bandwidths for determining the response speed from when the laser light is received until the information on the light amount of the laser light is output. .

  Therefore, when a high resolution is required for the observation image of the measurement sample 10 acquired using the scanning laser microscope of FIG. 5, the user gives an instruction to the instruction unit 300 to widen the bandwidth of the light receiving system 180. Like that. When the computer 200 obtains this instruction from the instruction unit 300, the computer 200 has a wider bandwidth (that is, in the band limiting amplification unit 530) between the first light receiving system 511 and the second light receiving system 521. Based on the luminance information output from the capacitor C2 having the smaller value, processing for generating an observation image of the measurement sample 10 is performed. Then, the resolution of the observation image of the obtained measurement sample 10 is increased.

  On the other hand, when it is necessary to measure the height of the measurement sample 10 with high accuracy using the scanning laser microscope of FIG. 5, the user instructs the instruction unit 300 to narrow the bandwidth of the light receiving system 180. To give. When the computer 200 obtains this instruction from the instruction unit 300, the computer 200 has a narrower bandwidth (that is, in the band limiting amplification unit 530) between the first light receiving system 511 and the second light receiving system 521. Based on the luminance information output from the capacitor C2 having the larger value, a process for measuring the height of the measurement sample 10 is performed. Then, since the S / N ratio of the light receiving system 180 is improved, the accuracy of the height measurement of the measurement sample 10 is increased.

  Of course, as described above, the selection of the luminance information processed by the computer 200 is changed based on the operation mode (high resolution priority mode or high accuracy measurement mode) related to the instruction acquired by the instruction unit 300. You may make it improve the operativity of a scanning laser microscope.

  As described above, a plurality of light receiving systems are provided that receive laser light that is reflected by the surface of the measurement sample 10 and passes through the objective lens 130 and the confocal stop 510 or 520 and outputs information on the amount of light. By making the respective bandwidths different from each other, it is possible to provide characteristics in accordance with the user's request. In addition, since the luminance information can be acquired in parallel by providing a plurality of light receiving systems in this way, acquisition of an observation image of the measurement sample 10 with high resolving power and high-precision height measurement of the measurement sample 10 are possible. Can be performed simultaneously.

  The luminance information acquired in parallel in this way is used to create a three-dimensional image (a bird's-eye view of the shape) of the measurement sample 10 using high-precision height measurement data, and the three-dimensional The computer 200 is caused to execute image processing for pasting a high-resolution omnifocal image of the measurement sample 10 on the surface of the image and displaying it on the display unit 400 by executing a control program for performing the image processing. It is also possible.

  Further, by acquiring the luminance information in parallel in this way, the luminance values indicated by the luminance information output from the light receiving system with a narrow bandwidth are less than the predetermined threshold value. It can replace with the luminance value shown by the luminance information output from a wide light receiving system, and the generation of the observation image of the measurement sample 10 and the height measurement can also be performed.

  In this way, in the generated observation image, a portion where a sufficient amount of reflected light can be obtained from the measurement sample 10 is output from a light receiving system with a narrow bandwidth (since a sufficient S / N ratio is originally obtained). The brightness value indicated by the brightness information is used, and the part with less reflected light of the laser light, such as the slope or rough surface, is output from the light receiving system with a wide bandwidth and excellent S / N ratio. Therefore, the luminance value indicated by the luminance information is used, so that the observation image can be generated in a wide dynamic range from the high reflectance region to the weak light region and without losing the resolution. And height measurement can be performed.

  As described above, according to any of the embodiments of the present invention, when a high resolving power is required, or when a high-precision height measurement is required and degradation of the resolving power is acceptable, the user's request It is possible to provide characteristics along the line. Further, since no mechanical operation is performed to change this characteristic, the apparatus can be configured in a small size, and the cost of the apparatus can be reduced. Furthermore, the measurement time is short compared to a method that integrates luminance images. In addition, since the diameter of the confocal stop can be fixed, a high-accuracy positioning mechanism is not necessary, and the sectioning effect of the confocal optical system is not reduced, so high accuracy and high resolution are possible. It is.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to each embodiment mentioned above, A various improvement and change are possible within the range which does not deviate from the summary of this invention.

It is a figure which shows the 1st example of a structure of the scanning laser microscope which implements this invention. It is a figure which shows the detailed structure of the light-receiving system shown in FIG. It is a figure which shows the 1st example of a detailed structure of a bandwidth change part. It is a figure which shows the 2nd example of a detailed structure of a bandwidth change part. It is a figure which shows the 2nd example of a structure of the scanning laser microscope which implements this invention. It is a figure which shows the detailed structure of the 1st light reception system shown in FIG. 5, and a 2nd light reception system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Measurement sample 100 Laser microscope main body 110 Control part 120 Laser light source 130,501 Beam splitter 140 XY scanning mechanism 150 Objective lens 160 Objective lens switching mechanism 170 Confocal stop 180 Light receiving system 181 Light receiving element 182 Amplifying part 183 IV conversion part 184 Bandwidth change unit 185 amplifier 185-1, 185-2, 185a, 185b, 185c operational amplifier 186 signal selection circuit 190 Z scanning mechanism 200 computer 300 instruction unit 400 display unit 510 first confocal stop 511 first light receiving system 512 1st light receiving element 513 1st amplification part 520 2nd confocal stop 521 2nd light reception system 522 2nd light reception element 523 2nd amplification part 530 Bandwidth limited amplification part R0 Load resistance R1, R2, Ra, Rb, Rc Feeder Click resistor Rs ground resistance C0 capacitor C1, C2, Ca, Cb, Cc capacitor

Claims (6)

A light-receiving system that receives the laser light that is reflected by the surface of the sample while irradiating the surface of the sample while being two-dimensionally scanned, passes through the objective lens and the confocal stop, and outputs information on the amount of light;
Bandwidth changing means for changing a bandwidth of the light receiving system for determining a response speed from when the light receiving system receives the laser light to outputting information on a light amount of the laser light;
A scanning laser microscope characterized by comprising: An operation mode selection instruction acquisition means for acquiring an instruction to select one of the operation modes set in advance for the scanning laser microscope;
The bandwidth changing unit changes the bandwidth of the light receiving system based on the operation mode according to the instruction acquired by the operation mode selection instruction acquiring unit.
The scanning laser microscope according to claim 1. The light receiving system includes a photoelectric conversion element that receives the laser light and outputs an analog electric signal having a magnitude corresponding to the amount of the laser light,
The amount of information of the laser beam output from the light receiving system is the analog electrical signal,
The bandwidth changing means includes
A plurality of analog signal amplifiers having different bandwidths for amplifying the analog electrical signal;
Amplifier switching means for switching an analog signal amplifier used for amplification of the analog electric signal;
Comprising
The scanning laser microscope according to claim 1 or 2. The light receiving system includes a photoelectric conversion element that receives the laser light and outputs an analog electric signal having a magnitude corresponding to the amount of the laser light,
The amount of information of the laser beam output from the light receiving system is the analog electrical signal,
The bandwidth changing means includes
An analog signal amplifier for amplifying the analog electrical signal;
Circuit constant changing means for changing the circuit constant of the analog signal amplifier determining the bandwidth of the analog signal amplifier;
Comprising
The scanning laser microscope according to claim 1 or 2. There are multiple light receiving systems that receive laser light that is reflected on the surface of the sample while irradiating the surface of the sample while being scanned two-dimensionally, passes through the objective lens and the confocal stop, and outputs information on the amount of light. And
The light receiving system has mutually different bandwidths for determining a response speed from receiving the laser light to outputting information on the light amount of the laser light.
A scanning laser microscope. An operation mode selection instruction obtaining means for obtaining an instruction to select one of the operation modes set in advance for the scanning laser microscope;
A light amount information selecting unit that selects information on the light amount of the laser light output by each of the plurality of light receiving systems, based on the operation mode according to the instruction acquired by the operation mode selection instruction acquiring unit;
The scanning laser microscope according to claim 5, comprising: