JP2007155527A - Apparatus for observing surface of object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To observe and confirm an observation region on an object by displaying it as an image on an observation display part before scanning the region with a scanning optical system. <P>SOLUTION: An optical system 1 in which the surface of the object is scanned with a luminous flux from a laser light source 2 via a rotating mirror 5 with the rotation axis in the perpendicular direction is constituted so that it is once imaged on a primary imaging surface. An image optical system 16 having a vertical structure in which the luminous flux from the primary imaging surface is directed toward the object placed so that the surface is in the horizontal direction is constituted and installed between the primary imaging surface and the object. The surface of the object is illuminated by a separately installed illumination optical system from the upper part of the image optical system 16, and the reflection light from the illumination area is sent from the image optical system to the observation display part 19 so as to be confirmed as the observation image. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to an apparatus that scans the surface of an object with a light beam from a laser light source, scans the shape two-dimensionally, and observes and measures the amount of displacement in the height direction. Display on the display screen for observation. After confirming that this display image substantially matches the desired observation area, scan the object surface using the scanning optical system, and change the height of the surface shape. The amount is monitored and measured.

An apparatus for observing and measuring an object surface shape using an optical system such as a microscope is used in various fields. One of the problems with such devices is that the area on the object to be observed and measured is limited by the field of view of an optical device such as a microscope. Therefore, in order to observe and measure the object surface over a wide area in the peripheral area adjacent to one field of view, it is necessary to take measures such as moving the microscope or the object for each field of view and joining the obtained images. . For example, if you connect a digital camera to a microscope and capture object surface images for each field of view as images, display them as close to each other as possible and display them as a single image on a personal computer, etc., and view the displayed image as a wide-range image. can do. However, although the range that can be captured as one field of view of the microscope is at most about 0.5 × 0.5 mm on the object, although depending on the magnification, for example, when trying to capture the range of about 10 × 10 mm, joining of the image joints for each field of view is possible. Accuracy is required. If the joining accuracy is unsatisfactory or variation occurs, the image is distorted when handled as the entire image, and it is necessary to consider improving the accuracy of the entire apparatus. Furthermore, it is necessary to consider vibrations that occur with movement of the microscope and the object for each field of view.
In addition, when trying to measure the amount of displacement in the height direction (Z direction) of the object surface shape to be observed and measured with a device such as a microscope, for example, by using a means such as an autofocus function, Measurement within the field of view can be performed. However, in order to obtain resolution, a confocal optical system with a shallow depth of focus is adopted. Therefore, it has been difficult to obtain an optical system with a long focal depth. Further, even if the above-mentioned problem of the joint portion is cleared, the measurement in the height direction cannot be performed at the joint portion generated for each visual field, and thus a wide range measurement cannot be performed.
On the other hand, a laser scanner is known as a device that captures a wide area of an object surface as an image and displays it on a display unit. In this method, the object surface is scanned with, for example, a laser beam, and the reflected light is captured as image data. This makes it possible to scan in a high range and obtain image data at high speed. However, in general, a scanner only measures the surface of an object and cannot measure the amount of displacement of the surface shape in the height direction.

  In order to deal with such a problem, the applicant of the present application previously proposed Patent Document 1. The apparatus according to Document 1 will be briefly described with reference to the plan view of FIG. Reference numeral 1 denotes a scanning optical system. A light beam from the laser light source 2 travels through a lens 3 and a beam splitter 4 to a rotating mirror 5. The rotating mirror 5 is rotated by a motor 6, and the surface of the object 8 is scanned by the light beam that has passed through the fθ lens 7 by changing the rotation angle. The light beam that has scanned the surface of the object 8 returns as a reflected light, travels forward through the lens 7 and the rotating mirror 5, and is reflected and branched by the beam splitter 4, and passes through the mirror 9 and the lens 10 to the light receiving unit 11 such as a photomultiplier. Reach. A signal photoelectrically converted by the light receiving unit 11 is processed by a control unit 12 that controls the entire apparatus, stored in an internal image memory, and then transmitted to and displayed on the screen of the display unit 13. If the direction in which the surface of the object 8 is scanned by the rotary mirror 5 is assumed to be the X direction, the X and Y scanning regions can be obtained by moving the entire object 8 in the Y direction. The light beam scanned along the surface shape of the object 8 is stored as image data and displayed on the screen of the display unit 13 as an image of the scanning region. Since this display image captures the luminance that varies depending on the surface shape of the object, the image data from the light receiving unit 11 can be regarded as a measurement value according to the light amount difference. Therefore, the image displayed on the display unit 13 by this light amount difference can be observed as an image representing the object surface shape height direction displacement amount. In addition, the above-mentioned Patent Document 1 also shows a measuring unit that calculates the distance between the focal position of the lens 7 and the surface of the object 8 by an autofocus function or the like and calculates this as a displacement amount in the object surface shape height direction. The description is omitted here.

If such an apparatus is used, a wide area of the surface of the object 8 is scanned at high speed by the scanning optical system 1 and the reflected light is projected onto the light receiving unit 11 to create image data, which is sent to the display screen 13 for display. By doing so, the amount of displacement in the height direction of the object surface shape can be observed.
However, in such an apparatus, when the surface of the object 8 is scanned by the scanning optical system 1, the image of the scanned portion or the image of the scanned portion can be confirmed on the display screen, but the unscanned portion is confirmed. I can't. That is, the scanning area cannot be confirmed as an image in advance. Therefore, it cannot be guaranteed that the portion being scanned now matches the required observation area.
Further, in the scanning optical system 1 of FIG. 1, the rotation axis of the motor 6 is perpendicular to the paper surface, and the surface of the object 8 is scanned by the rotating mirror 5 attached to the rotation axis. Therefore, the surface of the object 8 to be scanned is also installed so as to be perpendicular to the paper surface. However, an object handled by a general optical microscope or the like is usually installed so that the surface thereof is in the horizontal direction, and the operability including movement in the X and Y directions is better. Therefore, if the entire apparatus of FIG. 1 is rotated 90 degrees to the right and the scanning surface of the object 8 is installed in the horizontal direction, the rotation axis of the motor 6 is also rotated 90 degrees to the right. turn into. For this reason, a slight deflection occurs on the rotating shaft, which causes unstable factors such as rotation unevenness and blurring, and the scanning image displayed on the display screen is distorted, thereby hindering accurate observation. Therefore, in the example of FIG. 1, even if there is some inconvenience in operability, the configuration of the scanning optical system 1 in which the rotation axis of the motor 6 is the vertical direction has to be made.
Japanese Patent Application No. 2005-188492

  An object of the present invention is to solve the above-mentioned problem and to obtain an apparatus that can confirm an observation area on an object as an image in advance, and thereby an area to be scanned by a scanning optical system is almost equal to an observation area that is required. It is to ensure that they are consistent. That is also to obtain an apparatus having an overall optical system in which the surface of the object to be observed is in the horizontal direction while the rotation axis of the rotary mirror installed in the scanning optical system is in the vertical direction. Further, it is necessary to obtain a device with improved accuracy and function of the entire device.

In order to solve the above-mentioned problems, the present invention provides a scanning optical system for directing a light beam from a laser light source to an imaging surface of an fθ lens through a rotating mirror having a vertical rotation axis, and a light beam from the fθ lens imaging surface. The image optical system having a vertical structure with an optical path passing through a relay lens and an objective lens so that the surface is directed to the object installed in the horizontal direction, and the object surface is illuminated through the image optical system, and the illumination area An illumination optical system that conveys the image to the observation display unit as an image to be observed, and scans the object surface in the illumination area with the scanning optical system and the image optical system, and receives the reflected light flux through the image optical system and the scanning optical system, A branch measurement optical system in the scanning optical system that detects the amount of displacement in the height direction of the object surface shape as a light amount difference, and after confirming a desired region of the horizontal object surface in advance as an observation image on the observation display unit Scan the object surface In addition, the value detected by the branch measurement optical system is displayed as an image signal on the measurement display unit.
According to a second aspect of the present invention, in the object surface observation apparatus according to the first aspect, a light transmitting portion disposed in the optical detection system, which guides the light beam that has passed through the fθ lens in the scanning optical system to the timing detection optical system. In this case, the grating is alternately scanned at a constant pitch and scanning is performed to obtain the image signal capturing timing by the branch measurement optical system with the passing light flux.
According to a third aspect of the present invention, in the object surface observation apparatus according to the first aspect, a stop is installed at a position corresponding to the entrance pupil of the objective lens at a position between the relay lens of the image optical system and the objective lens. .
According to a fourth aspect of the present invention, in the object surface observation apparatus according to the first aspect, a galvanometer mirror scanner is installed at a position corresponding to the entrance pupil of the objective lens at a position between the relay lens of the image optical system and the objective lens. The scanning is performed in a direction orthogonal to the scanning direction on the object by the system.
According to a fifth aspect of the present invention, in the object surface observation apparatus according to the first, third, and fourth aspects, the objective lens of the image optical system can be exchanged. 6. The observation apparatus for an object surface according to claim 1, wherein the illumination area reflected light on the object illuminated by the illumination optical system and the image optical system is projected onto the observation image light receiving unit via the image optical system. Then, this signal is transmitted to the object installation stage as a Z-direction autofocus signal of the object.

In the present invention, an image optical system is installed between the scanning optical system and the object, the object surface is illuminated using the image optical system, and the reflected image is displayed on the observation display unit. Therefore, the observation area on the object surface is confirmed in advance on the display unit, and if necessary, the object is moved in the X and Y directions to display the desired observation area on the object on the display unit, and then the scanning optical system The range corresponding to the observation area can be scanned. As a result, it can be assured that the area scanned in advance by the scanning optical system and the required observation area substantially coincide.
Also, since the light beam traveling from the scanning optical system to the object is once imaged on the primary imaging surface and then directed to the object through the image optical system, the image optical system is a general microscope. Like the vertical type. Thus, the object surface can be handled as a horizontal direction, and the rotation axis of the rotating mirror in the scanning optical system can be kept in the vertical direction. As a result, the scanning optical system can maintain accuracy, and the handling of the object and the operability of the entire apparatus can be improved.
Furthermore, the installation of the image optical system makes it possible to insert a grating between the primary image forming plane and the fθ lens, and can cover uneven rotation of the motor for the rotating mirror, fθ characteristics of the fθ lens, manufacturing errors, and the like. . This improves the scanning accuracy performed by the scanning optical system. Further, the installation of the image optical system makes it possible to exchange the objective lens for magnification conversion. This means that the magnification conversion, which was not possible with the conventional scanning system, can be performed without changing the configuration in the scanning optical system or the arithmetic processing in the control unit. It is valid. Further, the installation of the image optical system makes it possible to install a diaphragm in the optical system. As a result, the NA (numerical aperture) of the image handled by the scanning optical system can be changed, so that, for example, object surface scanning can be performed in which the laser spot size is classified into high accuracy, normal accuracy, and low accuracy. .
The image optical system can be installed by installing a galvanometer mirror scanner in the optical system. This scanner can scan the object two-dimensionally in both the X direction by the rotating mirror and the Y direction by the scanner. Accordingly, it is possible to increase the scanning speed, remove the vibration caused by the movement of the object in the Y direction, remove the distortion of the optical system, and improve the resolving power. Furthermore, the installation of the image optical system makes it possible to easily introduce an autofocus function and improve the focusing accuracy. In this way, the accuracy can be improved and new functions can be obtained as a whole.

FIG. 2 is a diagram for explaining the outline of the present invention. In the optical system shown as the front view of FIG. A, when the aperture of the fθ lens 7 is D, the laser spot diameter on the object 8 is φ, and the focal length of the lens 7 is f,
φ = α × f / D × λ
(Α = coefficient, λ = wavelength).
In order to increase the resolving power on the object, it is only necessary to decrease φ, so D increases. Conversely, if D is made small, φ becomes large and the resolving power decreases. When f is increased, φ is increased, and when f is small, φ is also decreased. These are contrary to the gist of the present invention in which the resolution is improved and the object is placed on a horizontal plane as an optical system having a vertical structure like a general microscope. That is, if f is lengthened and the mirror 14 is installed in the optical path as indicated by the dotted line in FIG. A, an optical system having a vertical structure can be obtained. However, this increases φ and reduces the resolution. If this φ is reduced to increase the resolving power, the value of D increases and the installation of the mirror 14 becomes difficult.
In order to cope with such a situation, in the present invention, an optical system for images is installed between the scanning optical system 1 and the object 8. This will be described with reference to FIG. This figure is for explaining the optical system. The scanning optical system 1 shown on the left side of the figure is a plan view similar to that of FIG. 1, and the image optical system 16 described on the left side of the figure is shown in FIG. 2A. It is shown as a front view similar to FIG. In FIG. B shown as an explanatory explanatory diagram of such anomalies, the light beam from the scanning optical system 1 once forms an image at the focal position 15 of the lens 7. The light beam projected at this position as the primary imaging plane 15 is directed to the object 8 through the image optical system 16. A beam splitter 17 is installed in the image optical system 16 to change the optical path by 90 degrees, so that the optical system 16 has a vertical structure. This makes it possible to set the surface of the object 8 in the horizontal direction while keeping the rotation axis of the rotary mirror 5 in the vertical direction. An illumination optical system 18 is installed above the image optical system 16 having a vertical structure, and the surface of the object 8 installed in the horizontal direction is illuminated using the image optical system 16. The reflected light from the illuminated object 8 is sent to the observation display unit 19 via the image optical system 16 and the illumination optical system 18 and displayed. Thus, before scanning the object 8 with the scanning optical system 1, the region to be scanned on the object can be confirmed on the observation display unit 19 as an observation image. That is, the area on the object 8 to be observed in advance can be confirmed on the screen of the display unit 19. Moreover, since the D of the lens 7 can be increased and the laser beam spot diameter φ on the object 8 can be kept small, the resolving power can be maintained. Next, examples will be described.

FIG. 3 is a schematic perspective view showing the overall configuration. In the figure, reference numeral 1 denotes an optical system similar to the scanning optical system shown in FIGS. 1 and 2, and each member constituting the optical system is fixed to a housing accommodating the scanning optical system 1 by a holding material not shown. ing. The light beam from the laser light source 2 reflected by the rotating mirror 5 installed so that the rotation axis is in the vertical direction forms an image on the primary imaging surface 15 through the fθ lens 7. The light beam reflection position on the surface of the rotating mirror 5 corresponds to the position corresponding to the entrance pupil of the fθ lens 7, but the position of the primary imaging surface 15 corresponds to the position where the object 8 in FIG. 1 is installed, and the light beam from this position is the image. Proceed to optical system 16. The optical system 16 has its optical path bent in a right angle direction by a beam splitter 17 and becomes a vertical optical system toward an object 8 installed so that the surface thereof is in the horizontal direction. A relay lens 20 and an objective lens 21 are installed in the middle of the optical path of the optical system. Members such as the beam splitter 17, the relay lens 20, and the objective lens 21 are fixed to a housing that houses the image optical system 16 by a holding material (not shown). The objective lens 21 has various magnifications required, and is inserted into the optical system 16 in a replaceable manner. However, a general mechanism may be adopted, and description thereof is omitted here. The object 8 is installed on a first stage 22 that can move in the X and Y directions and a second stage 23 that moves in the Z direction, and moves manually or by a command from the control unit 12. If the direction in which the surface of the object 8 is scanned by the rotating operation of the rotating mirror 5 is set to the X direction as in FIG. 1, the first stage 22 automatically moves in the Y direction at a predetermined pitch according to a command from the control unit 12. Make up.

A beam splitter 25 is installed on the extension above the optical axis 24 in the image optical system 16 to constitute the illumination optical system 18. The optical system 18 includes a light source 26 such as an LED and a lens 27, and the light source 26 emits light when receiving a command from the control unit 12. Then, the light beam is reflected by the beam splitter 25, proceeds to the image optical system 16, passes through the beam splitter 17, and illuminates the surface of the object 8 through the relay lens 21 and the objective lens 22. The reflected light from the region 28 on the illuminated object 8 returns to the image optical system 16, passes through the beam splitter 25 of the illumination optical system 18, and is projected onto the observation image light receiving unit 29 such as a CCD, and is used for the observation image. The image is displayed on the display unit 19 as an image. Therefore, the illumination area 28 on the object 8 becomes an observation area and is displayed on the display unit 19. The displayed image is confirmed, and if necessary, the first stage 22 is moved in the X and Y directions and the second stage 22 is moved. The stage 23 is moved in the Z direction, and the desired observation area on the object 8 is displayed on the display unit 19 in a focused state.
An optical system 30 for detecting the origin is shown at the upper left of the rotating mirror 5, and a light beam from a light source 31 such as an LED that receives light from the controller 12 emits light through a lens 32 and a mirror 33. It is reflected and reaches the light receiving unit 34. A signal received by the light receiving unit 34 in accordance with the rotating operation of the rotating mirror 5 is sent to the control unit 12 and becomes an origin detection signal.

  Next, an operation process of scanning the surface illumination area 28 of the object 8 confirmed by the observation image display unit 19 and detecting the amount of displacement in the object surface height direction as a light amount difference will be described with reference to FIGS. 4 and 5. . FIG. 4 is a diagram for explaining the display screen of the observation display unit 19, and FIG. 5 is a flowchart for explaining the work process. First, in step 35 of FIG. 5, the magnification of the objective lens 21 to be inserted into the image optical system 16 is selected and a desired lens is mounted. Next, in step 36, a command is given from the control unit 12 to the light source 26 of the illumination optical system 18 to turn on (ON). Then, as described above, the light beam is reflected by the beam splitter 25 and illuminates the object 8 through the beam splitter 17 of the image optical system 16, the relay lens 20, and the objective lens 21 of the selected magnification. The light beam reflected by the area 28 on the illuminated object 8 returns in the forward path, passes through the beam splitter 25 of the illumination optical system 18, is projected onto the light receiving unit 29, and is displayed on the display unit 19 as an image of the illumination area 28. . This displayed image has been subjected to magnification conversion by the objective lens 21, and the converted image is displayed as an observation area. This displayed observation area is indicated as 37 in the display section 19 display screen 19a of FIG. Observe and confirm the image displayed in the observation area 37, move the second stage 23 in the Z direction to focus, and move the first stage 22 in the X and Y directions until the image of the desired area is displayed. Then, the observation region 37 on the object is selected (step 38). Next, in step 39, a designated area 40 is set in the observation area 37 in the display screen 19a by using a keyboard and a mouse (not shown) connected to the control unit 12. The designated area 40 will be described later. When the designated area 40 is set in the display screen 19a, the process proceeds to step 41. First, an ON command is given to the laser light source 2 of the scanning optical system 1 from the control unit 12 to turn on, and an ON command is also given to the motor 6 to rotate the rotating mirror 5. The light source 2 is turned on through the lens 3, the beam splitter 4, the rotating mirror 5, and the lens 7 toward the temporary imaging surface 15. Then, a beam spot is formed in the illumination area 28 of the object 8 through the image optical system 16. When the rotating mirror 5 rotates, the spot scans in the observation region 37 on the object, for example, in the X direction. The size of the relationship between the actual scanning range by the spot and the observation region 37 can be freely selected, but in the example of FIG. 4, the scanning start point S and end point E of the spot are the start and end points of the observation region 37. It is consistent with. Lines 42a, 42b, and 42c shown in the figure indicate the scanning trajectory of the spot, and the line 42c represents a state when the vehicle has progressed halfway. In order to manage the relationship between the scanning range and the observation region 37, an origin detection signal from the origin detection optical system 30 is transmitted to the control unit 12.

  When the laser beam spot becomes a line 42 and scans the object surface, the reflected light returns through the image optical system 16, passes through the primary imaging plane 15, passes through the lens 7, the rotating mirror 5, and the beam splitter 4, and is received. Head to part 11. The light beam projected on the light receiving unit 11 becomes an image signal and goes to the control unit 12, and the image signal in the designated area 40 is extracted in step 43. This is executed by the control unit 12 comparing the area defined by the designated area 40 set in the display screen 19a with each scanning line 42. The image signals sequentially obtained by moving the rotating mirror 5 and the object 8 in the Y direction in this way are stored in the image memory accommodated in the control unit 12 in step 44, and the contents are sent to the measurement display unit 13 in step 45. Displayed. This displayed image is in the designated area 40 and is limited compared to the image of the observation area 37 displayed on the other observation display unit 19, but the magnification is converted by the objective lens 21. It is the same to become a thing.

The image signal stored in the image memory (not shown) is also a measurement value signal obtained by measuring the luminance that changes according to the amount of displacement in the height direction of the object surface as a light amount difference. If the measurement value signal of the designated area 40 is sequentially stored in the image memory by moving the rotating mirror 5 and the object 8 in the Y direction, it is sent to the measurement display unit 13 and displayed as a measurement image in step 45. Is done.
Thus, the illumination area 28 specified on the object 8 becomes an observation area 37 and is first displayed on the observation display unit 19, and the scanning image in the designated area 40 set in the observation area 37 measures the displacement in the height direction. The value is displayed on the measurement display unit 13 as a value. The display units 19 and 13 have similar functions, but the observation display unit 19 redisplays the image in the designated area 40 so that the image in the designated area 40 is rewritten for each scanning of the lines 42a, b, c. It will be done.

  The focusing operation in step 38 will be described. In FIG. 3, the reflected light from the illumination area 28 on the object 8 illuminated through the illumination optical system 18 and the image optical system 16 is projected onto the light receiving unit 29 for image observation. As described above, the reflected light is generated as a light amount difference in luminance that changes in accordance with the amount of displacement in the height direction of the object surface, and is transmitted from the control unit 12 to the second stage 23. It can be an autofocus signal. That is, the autofocus command signal is obtained by using the light amount difference as the movement command signal. Specific means for auto-focusing is also described in Patent Document 1 and the like and will not be described. However, by doing so, a signal for moving the second stage 23 in the Z direction can be obtained. Yes, you can automate focusing.

In the second embodiment, a timing detection optical system 46 for detecting the timing at which the branch measurement optical system captures an image signal is newly installed. The optical system 46 will be described with reference to FIG. This figure is an irregular explanatory view showing the scanning optical system 1 as a plan view and the image optical system 16 and the timing detection optical system 46 as a front view as in FIG. 2B. In the figure, the light beam from the fθ lens 7 in the scanning optical system 1 is reflected by the beam splitter 47 on the way to the primary imaging plane 15. The reflected light beam travels through the grating 48 and the lens 49 to the light receiving unit 50. An example of the grating 48 is shown in FIG. 6B. However, slit-like light transmitting portions 48a and light blocking portions 48b are alternately arranged at a constant pitch on a thin plate, and the rotating operation of the rotating mirror 5 of the scanning optical system 1 is performed. The light beam that has passed through the lens 7 scans the grating 48. Then, the light beam that has passed through the light transmitting portion 48 a of the grating 48 is sent out in a pulse shape to the light receiving portion 50, and the light receiving portion 50 sends the detection signal to the A / D converter 51 in the control portion 12.
On the other hand, the light beam that has passed through the beam splitter 47 of the timing detection optical system 46 passes through the image optical system 16 through the primary imaging plane 15 and scans the surface of the object 8 as described above. The reflected light flux returns to the two optical systems 16 and 1 and is branched by the beam splitter 4, and is transmitted from the light receiving unit 11 to the A / D converter 51 in the control unit 12 as an image signal. The image signal transmitted to the A / D converter 51 is taken into the image memory 52 by the timing signal detected by the timing detection optical system 46. The image signals sequentially stored in the image memory 52 are displayed as images on the measurement display unit 13 shown in FIG. 3 or the like or as displacements in the object shape height direction.

FIG. 7 is a diagram for explaining the timing signal of the timing detection optical system 46. In the figure, reference numeral 53 denotes a reference clock signal generated in the control unit 12. This clock signal is a reference and is generated at an accurate timing. If the image signal from the light receiving unit 11 is taken into the image memory 52 based on this timing, an accurate reproduced image is displayed on the display unit 13. However, although the fθ characteristic and manufacturing error of the fθ lens 7 can be measured, the occurrence of jitter or the like in the motor 6 for the rotating mirror 5 cannot be predicted. For this reason, the timing of the image taken into the image memory 52 varies as indicated by 54 in FIG. Then, the image on the measurement display unit 13 is distorted and becomes inaccurate. Therefore, when the dimensions of the display image are measured on the display unit 13 screen, or when a singular part in the display image, for example, a foreign object or a flaw is displayed, the shape changes if the image is distorted. End up. In this embodiment, the grating 48 is installed in the optical system 46, and the light beam passing through the slit-like light transmitting portion 48a is used as a timing signal for image capture. In FIG. 7, this is shown as the timing signal 55, but is equivalent to the reference clock 53.
By installing such a timing detection optical system 46, the overall accuracy of the scanning optical system 1 can be improved, and the measurement accuracy in the measurement display unit 13 can be increased. This is also a result obtained by separately configuring the scanning optical system 1 and the image optical system 16 independently.

FIG. 8 is an explanatory diagram when the diaphragm 56 is installed in the image optical system 16, and FIG. 9 is an explanatory diagram of the optical system. Example 3 will be described with reference to these drawings. In FIG. 8, a diaphragm 56 is installed between the relay lens 20 and the objective lens 21 in the image optical system 16. The aperture of the diaphragm 56 can be varied by a command from the keyboard via the control unit 12 or manually. When the aperture is changed, the diameter of the light beam passing through the stop 56 is changed, and the diameter of the scanning light beam from the scanning optical system 1 reaching the object 8, that is, the diameter of the beam spot is changed. For example, when the aperture of the diaphragm 56 is narrowed, the spot diameter on the object 8 increases. The spot diameter will be described using the optical system of FIG.
FIG. 9 shows the optical path from the rotating mirror 5 to the object 8 as a straight line, and the beam splitter 17 is omitted. When the rotating mirror 5 rotates and changes its reflection angle, the light flux from the laser light source 2 also changes its traveling direction according to the reflection angle. In the figure, this is shown as two light beams 57a and 57b. The light beam 57a is a light beam that passes on the central optical axis 24, and the other light beam 57b is a light beam that passes through the peripheral portion. Both luminous fluxes 57 travel toward the primary image plane 15 after passing through the lens 7. Then, the object is directed from the objective lens 21 to the object 8 by the relay lens 20. At this time, both light beams intersect between the relay lens 20 and the objective lens 21. A diaphragm 56 is installed at this intersection position (incidence pupil position of the objective lens 21). If the aperture of the diaphragm 56 is now narrowed down, the aperture becomes smaller as indicated by the arrow 58 at the left position of the diaphragm 56 in the figure. Therefore, the diameters of the light beams 58a and 58b are also small, and the beam spot φ on the object 8 is large. The object is scanned with the enlarged beam spot, thereby reducing the resolving power.
By setting the diaphragm 56 in this way, the resolution of the image handled by the scanning optical system 1 can be changed. Therefore, for example, it is possible to carry out surface scanning with ranks such as high accuracy, normal accuracy, and low accuracy. This means that when inspecting foreign matter or scratches on the surface of an object, it is possible to perform an operation of detecting only foreign matter or scratches of a certain size or more.

FIG. 10 is an explanatory diagram of an optical system when a galvanometer mirror scanner 59 is installed between the relay lens 20 and the objective lens 21. In the figure, the galvanometer mirror scanner 59 is installed instead of the beam splitter 17 shown in FIG. 8 and the like, and the installation position is a position corresponding to the entrance pupil of the objective lens at a position between the relay lens 20 and the objective lens 21. When such a mirror part of the scanner 59 is rotated in response to a command from the control unit 12, the light beam from the primary imaging surface 15 travels toward the object 8 through the objective lens 21 and scans in the Y direction. Thus, the object is scanned in the X and Y directions together with the X direction scanning on the object by the rotation of the rotating mirror 5. In the figure, the scanning lines are represented by 60a, b, and c, the light beam reflection point on the surface of the rotating mirror 5 is m1 (incidence pupil position of the fθ lens 7), and the light beam reflection point on the mirror surface of the scanner 59 is m2 (objective lens). 21 entrance pupil position). This makes it possible to minimize scanning distortion in the X and Y directions on the object, which is a drawback of the conventional X and Y galvanometer mirror scanner. In addition, since the installation of the scanner 59 removes the movement of the object in the Y direction, it is possible to increase the overall scanning speed and remove the vibration accompanying the movement of the object.
Although the illumination optical system 18 is omitted in FIG. 10, if the light beam from the illumination light source 20 shown in FIG. 3 or the like is directed to the mirror portion of the scanner 59 through the beam splitter 25, the light beam that has passed therethrough Illuminates the object 8. Then, the reflected light flux returns in the forward path, and is projected onto the light receiving unit 29 for the observation image, and the image is displayed on the display unit 19. As described above, in the embodiment of FIG. 10, the image optical system 16 is changed as compared with FIG. 3, but the function is the same. Further, the illumination optical system 16 may also be a method of illuminating from the upper periphery of the objective lens 21 instead of illuminating from the direction of the upper extension line of the optical axis 16 of the image optical system 16 as shown in FIG.

The top view for demonstrating a conventional apparatus. The figure explaining the outline of the present invention. The schematic perspective view which showed the whole structure of this invention apparatus. The figure explaining the display screen of the display part for observation. The flowchart explaining an operation process. The figure explaining a timing detection optical system. The figure explaining the timing signal of a timing detection optical system. Explanatory drawing of the aperture | diaphragm | set_stop installed in an image optical system. FIG. 9 is an explanatory diagram of the optical system in FIG. 8. Explanatory drawing of the galvanometer mirror scanner installed in an image optical system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Scanning optical system 2 ... Laser light source 4 ... Beam splitter 5 ... Rotating mirror 7 ... f (theta) lens 8 ... Object 11 ... Light-receiving part 12 ... Control part 13 * ··· Measurement display unit 15 ··· Primary imaging plane 16 ··· Image optical system 18 ··· Illumination optical system 19 · · · Display unit for observation 20 · · · Relay lens 21 · · · Objective lens 24 · · · .. Optical axis 26... Illumination light source 28... Illumination area 29... Observation image light receiving unit 30... Origin detection optical system 37 .. Observation area 40. Scanning line 46 ... Timing detection optical system 48 ... Grating 50 ... Light receiving part 51 ... A / D converter 52 ... Image memory 56 ... Aperture 59 ... Galvanometer mirror scanner

Claims (6)

A scanning optical system for directing the light beam from the laser light source to the imaging surface of the fθ lens through a rotating mirror having a vertical rotation axis;
An image optical system that receives the light beam from the fθ lens imaging surface, and has a vertical structure on the optical path so that the surface passes through a relay lens and an objective lens and is directed to an object that is installed in a horizontal direction;
Illumination optical system that illuminates the surface of the object via this image optical system, and transmits it to the observation display unit as an image to observe the illumination area;
Scanning that scans the object surface in the illumination area with a scanning optical system and an image optical system, receives the reflected light beam through the image optical system and the scanning optical system, and detects the height direction displacement of the object surface shape as a light amount difference. A branch measurement optical system in the optical system,
The desired area of the horizontal object surface is confirmed in advance as an observation image on the observation display unit, and then the object surface is scanned, and the value detected by the branch measurement optical system is displayed on the measurement display unit as an image signal. An object surface observation device characterized by the above. The light beam that has passed through the fθ lens in the scanning optical system is guided to the timing detection optical system, and scanning of the grating in which the light transmitting portions and the light blocking portions installed in the optical system are alternately arranged at a constant pitch is performed. 2. The object surface observation apparatus according to claim 1, wherein the image signal capturing timing by the branching optical system is obtained from the passing light beam. 2. The object surface observation apparatus according to claim 1, wherein a stop is installed at a position corresponding to the entrance pupil of the objective lens between the relay lens and the objective lens of the image optical system. A galvanometer mirror scanner is installed at a position corresponding to the entrance pupil of the objective lens between the relay lens and objective lens of the image optical system, and scanning is performed in a direction perpendicular to the scanning direction on the object by the scanning optical system. The apparatus for observing an object surface according to claim 1. 5. The object surface observation apparatus according to claim 1, wherein the objective lens of the image optical system is replaceable. The illumination light reflected on the object illuminated by the illumination optical system and the image optical system is projected onto the observation image light receiving unit via the image optical system, and the signal is transmitted to the object installation stage as the Z-direction autofocus signal of the object. The object surface observation apparatus according to claim 1, 3, 4, or 5, wherein the object surface observation apparatus is configured as described above.