JPH0129401B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a device for detecting the uneven shape of an object using interference fringes.

Configuration of a conventional example and its problems The specific configuration of a conventional shape recognition device is shown in FIG. 1 is a sample with a cylindrical surface; 2 is a light source that illuminates the sample; 3 is a reference light mirror; 4 is a beam splitter; the light emitted from light source 2 is split into two beams by beam splitter 4. The light reflected on the surface of the sample 1 and the light reflected on the reference beam mirror 3 interfere to generate interference fringes. 5 is an objective lens, 6 is a galvanometer mirror that scans the sample 1, 7 is a slit provided on the real image plane of the sample 1, and 8 is a photomultiplier tube that detects light passing through the slit 7. 9 is a filter that passes only light of a specific frequency. The waveform of interference fringes detected by the photomultiplier tube 8 when the sample 1 is scanned by the galvanometer mirror 6 is as shown in FIG. If the first and second waves of the interference fringes shown in Figure 2 are recognized, the surface shape of the sample can be determined from the wavelength of the illumination, but the amount of data becomes enormous and signal processing is required. In addition, it is difficult to recognize the surface unevenness of a sample with a complex surface shape.

OBJECTS OF THE INVENTION In view of the above drawbacks, an object of the present invention is to provide a shape detection device that detects the uneven shape of a sample by simple signal processing.

Structure of the Invention A microscope having an interference fringe generating means, an imaging device or a photoelectric conversion device provided in the vicinity of a real image plane of the microscope, and a determining means for determining the density level of the interference fringe obtained from the imaging device or the photoelectric conversion device. It comprises a detection means for detecting the relative position of the sample and the microscope, and determines interference fringe density level values at a plurality of locations on the surface of the sample, and detects the relationship between the sample and the microscope at each location based on the signal from the determination means. By detecting the relative position of the sample, the uneven shape of the sample can be detected with simple signal processing.

DESCRIPTION OF EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a front view showing the first embodiment of the present invention. In FIG. 3, 21 is a sample, 22 is a microscope, and the microscope 22 is a light source 2.
3. Beam splitter 24, reference beam mirror 2
5, an objective lens 26, a galvanometer mirror 27, a slit 28, and a photomultiplier tube 29.
The beam splitter 22 splits the light emitted from the light source 23 into two beams, and the light reflected by the sample 21 and the light reflected by the reference beam mirror 25 generate interference fringes. The slit 28 is provided on the real image plane of the sample 21, and the photomultiplier tube 29 is provided behind the slit 28 and converts the light passing through the slit 28 into an electrical signal. The galvanometer mirror 27 comes to rest at a plurality of locations depending on the applied voltage value, and determines the interference fringe detection position in the sample 21X direction. 30 is a microscope 22
This is a table on which the sample 21 is placed and moves in the Y direction. 31 is a motor, and the output shaft has a feed screw 32.
are connected to move the microscope 22 in the direction of the sample 21Y. The motor 31 is mounted on a slide table (not shown) and moves in the Y direction together with the feed screw 32. Reference numeral 33 denotes a position detection sensor that detects the position of the microscope. By detecting a change in the relative position of the sample 21 and the microscope 22 based on a position detection signal from the position detection sensor 33, it is possible to know the unevenness of the sample 21. 34 is a control device to which an interference fringe detection signal and a position detection signal are input, and a galvano drive signal is output.

An example of the configuration of the control device 34 will be explained with reference to FIG. Reference numeral 35 denotes a peak value detection circuit for detecting the peak values P ₁ , P ₂ , and P ₃ of the density levels of one cycle of the interference fringes shown in FIG. The peak value detection circuit 35 outputs the peak value of the gray level to the holding circuit 36 and the comparison circuit 37. The holding circuit 36 holds the peak value of the gray level inputted from the peak value detection circuit 35, and outputs the peak value of one cycle before to the comparison circuit 37. The comparison circuit 37 is the peak value detection circuit 35
The gray level peak value input from the holding circuit 3
6 is compared with the gray level peak value input one cycle before. Reference numeral 38 denotes a motor control circuit that controls the rotational direction of the motor 31 in a direction such that the peak value of the gray level input from the peak value detection circuit 35 to the comparison circuit 37 is greater than the peak value of the gray level input from the holding circuit 36. 39 is a motor drive circuit that drives the motor 31. 40 is a galvano drive circuit that makes the galvano mirror 27 stand still at a plurality of locations. Reference numeral 41 denotes a sampling circuit, which receives a sampling signal from the comparator circuit 37 when the peak value of the gray level one cycle before reaches its maximum, reads the galvano drive signal from the galvano drive circuit 40 at that time, and detects the position from the position detection sensor 33. Read the detection signal and select sample 2 from both values.
Detect the uneven shape of 1.

Next, the principle of detecting the position of the surface of the sample 21 in the Y direction in the uneven shape detection apparatus configured as shown in FIGS. 3 and 4 will be explained with reference to FIG.

When the light source 23 shown in FIG. 3 is an incoherent light such as a halogen light bulb, the coherent range is narrower than that of a coherent light such as a laser beam, and the density level of the interference fringes varies depending on the distance from the light source 23 to the sample 21. , becomes maximum when the distances from the light source 23 to the reference beam mirror 25 are equal, that is, when the lights emitted from the light sources at the same time interfere. Therefore, when the relative distance between the sample 21 and the microscope 22 is changed, the interference fringes become gradually clearer as shown in FIG. The interference fringes are the clearest at position B, where the distances are equal, and after passing through position B, the interference fringes gradually become unclear. When a change in the dark edge level of this interference fringe is detected by a photomultiplier tube 29 based on a change in the amount of light passing through the slit 28, the detection signal has a waveform as shown in FIG. 6b. Therefore, sample 2 when the density level of this interference fringe is maximum
1 and the microscope 22 at a plurality of locations in the X direction of the sample 21, the uneven shape of the sample 21 in the X direction can be known.

Next, the operation of this embodiment will be explained.

A galvanometer drive signal is applied to the galvanometer mirror 27, which swings by a predetermined angle and remains stationary, and a motor control circuit 38 drives the motor 31 in one direction via a motor drive circuit 39. At this time, sample 21
A photomultiplier tube 29 photoelectrically converts the density level of interference fringes caused by the light reflected from the reference beam mirror 25 and the light reflected by the reference beam mirror 25, and the peak value of the density level of one period of the interference fringe is detected by a peak value detection circuit 35. do.
The peak value detection circuit 35 outputs the gray level peak value to the holding circuit 36 and the comparison circuit 37. The holding circuit 36 outputs the peak value of the gray level one cycle before to the comparison circuit 37, and the comparison circuit 37 compares the two values. The gray level peak value of the holding circuit 36 is updated when the comparison circuit 37 completes the comparison. When the gray level peak value input from the peak value detection circuit 35 to the comparison circuit 37 is larger than the gray level peak value input from the holding circuit 36 one period before the interference fringe, the motor control circuit 38 rotates the motor 31 in the same direction. keep letting it happen. Next, holding circuit 3
When the peak value of the interference fringe one cycle ago inputted from 6 becomes larger than the gray level peak value inputted from the peak value detection circuit 35, that is, when the peak value of the interference fringe gray level peak value inputted from the holding circuit 36 becomes the maximum value of the interference fringe gray level peak value. is held, the comparator circuit 36 outputs a sampling signal to the sampling circuit 41. When the sampling signal is input to the sampling circuit 41, the galvano drive signal is read from the galvano drive circuit 40, the position of the sample 21 in the X direction is detected, and the position detection signal of the position detection sensor 33 is read, and the Y The relative position of the direction with respect to the microscope 22 is detected. The above operation is repeated at a plurality of locations in the direction of the sample 21X by changing the galvano drive signal applied to the galvanometer mirror 27, that is, the galvano drive voltage, to detect the uneven shape on the surface of the sample 21.

As described above, there is provided a microscope having an interference fringe generating means, a photoelectric converter, an interference fringe gray level peak value detection circuit, a holding circuit that holds the gray level peak value and outputs the peak value of one cycle before, and the peak value of the interference fringe. A comparison circuit that compares the output of the value detection circuit and the output of the holding circuit and a position detection means that detects the mutual position of the sample and the microscope are provided, and the sample and the sample near the maximum value of the peak value for each interference fringe density level cycle are provided. By detecting the position relative to the microscope at multiple locations on the sample surface, the uneven shape of the sample can be determined with high accuracy through simple signal processing.

A second embodiment of the present invention will be described below.

FIG. 7 is a block diagram showing an example of a control device in the second embodiment. The configuration other than the control device is the same as that of the first embodiment shown in FIG. 3. In FIG. 7, 42 is a detection circuit that detects the interference fringe density level, and 43 is a comparison circuit that compares the output value of the detection circuit 42 with a predetermined value of the interference fringe density level. 44 is a motor control circuit, and 45 is a motor drive circuit. 47 is a sampling circuit, and when the output value of the detection circuit 42 exceeds a predetermined value of the interference fringe density level, a sampling signal is inputted from the comparison circuit 43, and the galvano drive signal is read from the galvano drive circuit 46.
A position detection signal is read from the position detection sensor 33 and a shape signal of the sample 21 is output.

The operation of the shape detection device configured as described above will be explained below.

A galvanometer drive signal is applied to the galvanometer mirror 27, which swings by a predetermined angle and then comes to rest.The motor control circuit 44 rotates the motor 31 in one direction, and moves the microscope 22 in one direction. At this time, the interference fringe density level is photoelectrically converted by the photomultiplier tube 29 and detected by the detection circuit 42. The value of the interference fringe density level is input from the detection circuit 42 to the comparison circuit 43, and if it exceeds a predetermined value, the comparison circuit 43 outputs a sampling signal to the sampling circuit 47. When the sampling signal is input to the sampling circuit 47, the galvano drive signal is read from the galvano drive circuit 46 and the position of the sample 21 in the X direction is detected.The position detection signal is read from the position detection sensor 33 and the microscope detects the position of the sample 21 in the Y direction. Detects the relative position with.

The above operation is repeated at a plurality of locations in the direction of the sample 21X by changing the galvanometer drive signal applied to the galvanometer mirror 27, and the uneven shape of the surface of the sample 21 is detected.

As described above, a detection circuit that detects the density level of interference fringes and a comparison circuit that compares the density level of interference fringes detected by the detection circuit with a predetermined value are provided, and when the density level of interference fringes exceeds a predetermined value, the sample By detecting the relative position of the sample and the microscope at multiple locations on the sample surface, the uneven shape of the sample can be determined quickly and with simple signal processing.

Note that in the first embodiment and the second embodiment, a photomultiplier tube is used as a means for detecting interference fringes.
The present invention also includes the use of an ITV camera or the use of a diode array photoelectric conversion element.

Further, in the first and second embodiments, the sample is scanned by a galvanometer mirror, but the effect is the same even if the sample is moved or the slit is moved.

Effects of the Invention A microscope having an interference fringe generating means, an imaging device or a photoelectric conversion device provided near the real image plane of the microscope, and a determination device for determining an interference fringe density level value obtained from the imaging device or the photoelectric conversion device. , comprising position detection means for detecting the relative position of the sample and the microscope, which determines interference fringe density level values at a plurality of locations on the sample surface, and determines the relative position of the sample surface and the microscope based on the signal from the determination means. By detecting the position and detecting the uneven shape of the sample, the uneven shape of the sample can be known with high accuracy through simple signal processing.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the configuration of a conventional example, Fig. 2 is an explanatory diagram showing the waveform of interference fringes, Fig. 3 is an explanatory diagram showing an embodiment of the shape detection device of the present invention, and Fig. 4 is an explanatory diagram showing the embodiment of the shape detection device of the present invention. FIG. 5 is an explanatory diagram showing the shading level of interference fringes, FIGS. 6 a and b are explanatory diagrams showing changes in the shading level of interference fringes, and FIG. FIG. 2 is a block diagram showing a control device according to a second embodiment of the present invention. 21... Sample, 22... Microscope, 23... Light source, 24... Beam splitter, 25... Reference light mirror, 26... Objective lens, 27... Galvano mirror, 28... Slit, 29... Photoelectron Multiplier tube.

Claims (1)

[Scope of Claims] 1. A microscope having an interference fringe generating means, an imaging device or a photoelectric conversion device provided near the real image plane of the microscope, and determining an interference fringe density level value obtained from the imaging device or the photoelectric conversion device. and a position detection means for detecting the relative positions of the sample and the microscope, and the apparatus includes a determination means for determining the relative position of the sample and the microscope, and determines interference fringe density level values at a plurality of locations on the surface of the sample, and determines the relative position of the sample and the microscope based on the signal from the determination means. A shape detection device that detects the relative position to the microscope. 2. The determination means detects the peak value of the interference fringe density level value for each cycle, and determines the relative position of the sample and the microscope in the vicinity of the cycle in which the peak value of the density level value for each cycle becomes the maximum value. A shape detection device according to claim 1, which detects a shape. 3. The determination means retains a peak value detection circuit that detects the peak value of the interference fringe density level value for each cycle and the peak value detected by the peak value detection circuit, and determines the peak value of one cycle before. It consists of a holding circuit that outputs, and a comparison circuit that compares the gray level peak value that is output from the peak value detection circuit and the peak one cycle before that is output from the holding circuit, and the peak value is output from the peak value detection circuit. 2. The shape detection device according to claim 1, which detects the relative position between the sample and the microscope when the peak value becomes smaller than the peak value output from the holding circuit one cycle before. 4. The shape detection device according to claim 1, wherein the determining means detects the relative position of the sample and the microscope when the interference fringe density level value exceeds a predetermined level value. 5. The determining means includes a detection circuit that detects the interference fringe density level value and a comparison circuit that compares the output value of the detection circuit with a predetermined value, and the determination means comprises a detection circuit that detects the interference fringe density level value and a comparison circuit that compares the output value of the detection circuit with a predetermined value, and the determination means is configured such that the interference fringe density level value exceeds the predetermined value. 2. The shape detecting device according to claim 1, wherein the relative position between the sample and the microscope is detected by a signal from the comparison circuit indicating that the sample and the microscope are different from each other.