JP2950004B2 - Confocal laser microscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a confocal laser microscope, and more particularly to an improvement in measurement of an object to be measured in a Z-axis direction.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing an example of a conventional confocal laser microscope. In FIG. 6, light emitted from a laser light source 1 is condensed by a lens 2 and is incident on a half mirror 5 via an acousto-optic element 3 that changes the optical path in a two-dimensional direction orthogonal to the optical axis. The incident light is reflected by the half mirror 5 and is radiated on the DUT 7 by the lens 6. The reflected light (measured light) from the object 7 is
And is transmitted through the half mirror 5 to be incident on the photodetector 8. Thus, the image of the DUT 7 is captured by the photodetector 8.

In such a configuration, the acousto-optic device 3
By changing the optical path of the incident light of the half mirror 5 in a two-dimensional direction orthogonal to the optical axis, the scanning of the object 7 is performed. Here, as the photodetector 8, for example, a plurality of (for example, about 500.times.500) photodetectors having a size of about 20 .mu.m.times.20 .mu.m in one dot and having a pitch of about 5 .mu.m are used. On the other hand, the beam diameter of the light to be measured can be reduced to 1 μm or less because of the confocal structure.

[0004]

However, in the confocal laser microscope shown in the above prior art, when measuring the object 7 in the depth direction (Z-axis direction), the incident light beam is located at a desired depth position. The object to be measured must be moved in the vertical direction (Z-axis direction) together with the sample table (not shown) so that an image is formed, and there is a problem that positioning takes time.

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide a confocal laser microscope capable of positioning an incident light beam in a depth direction of an object to be measured at a high speed. Things.

[0006]

According to the present invention, there is provided a laser light source and an optical path control for changing an optical path of output light from the laser light source in a two-dimensional direction orthogonal to an optical axis. Element, a measuring optical system for guiding the output light of the optical path control element to the object to be measured, and a confocal laser microscope including a photodetector for detecting the light to be measured from the object to be measured, wherein the measuring optical system Providing a beam splitting element, a reflecting optical element, and an actuator for displacing the reflecting optical element along the optical axis direction, and changing an optical path length between the laser light source and the DUT according to the position of the reflecting optical element. It is characterized by the following.

[0007]

According to the present invention, the optical path length between the laser light source and the object to be measured can be changed by displacing the position of the reflection optical element along the optical axis direction by the actuator,
Positioning of the incident light beam in the depth direction of the measured object can be performed at high speed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of a confocal laser microscope of the present invention. In FIG. 1, the same elements as those in FIG. 6 are denoted by the same reference numerals, and duplicate description will be omitted. In FIG.
Reference numeral 9 denotes a polarizing beam splitter, and 10 denotes a quarter-wave plate, which are used as beam splitting elements. 11 is a mirror used as a reflection optical element, and 12 is an actuator for displacing the mirror 11 along the optical axis direction.

The operation of such a configuration will be described. The output light of the laser light source 1 is focused on the acousto-optic device 3 by the lens 2. By changing the frequency to be injected into the two acousto-optic elements 3 provided corresponding to the two-dimensional directions X and Y orthogonal to the optical axis by the drive circuit 4, the optical paths of the beams are respectively X and Y. Are scanned in the direction perpendicular to. This scanning beam is reflected by the half mirror 5 and collected by the lens 6. The beam condensed by the lens 6 is transmitted through a polarizing beam splitter 9 and a quarter-wave plate 10 and is reflected by a mirror 11. The beam reflected by the mirror 11 travels backward in the optical path, passes through the quarter-wave plate 10 again, and has a polarization direction of 90 °.
Rotated. As a result, the light is reflected by the polarization beam splitter 9 and is radiated on the DUT 7. The reflected light from the device under test 7 travels backward in the optical path, passes through the polarization beam splitter 9, the quarter-wave plate 10, the mirror 11, and the half mirror 5, and irradiates the photodetector 8.

Here, while the mirror 11 is fixed, the position where the beam is imaged in the depth direction (Z-axis direction) of the DUT 7 is constant. Is changed along the optical axis direction indicated by the arrow, the position where the beam is imaged in the depth direction of the DUT 7 can be changed. The mirror 11 can have a sufficiently small mass as compared with the conventional sample table, and can change its position at a high speed. Therefore, the positioning of the incident light beam in the depth direction of the DUT 7 can be performed at a high speed. I can do it.

Thus, a wide range of the DUT 7 can be measured at high speed in combination with the scanning of the optical path in the two-dimensional directions X and Y orthogonal to the optical axis by the acousto-optic element 3.

In the above embodiment, the use efficiency of light is increased by using a polarizing beam splitter and a quarter-wave plate as beam splitting elements. However, the intensity of light output from the laser light source 1 may be high. When the photoelectric conversion sensitivity of the photodetector 8 is high, a half mirror may be used.

In the above embodiment, an acousto-optic device is used as an optical path control device. However, a galvano mirror or a combination of a lens and an optical fiber may be used.

Although the light is shown as non-parallel light in the above embodiment, it may be a parallel light as shown in FIG. Here, the portion between the lenses 21 to 22 is a portion where the light is parallel. By using parallel light, alignment of optical elements such as lenses becomes easy, and the degree of freedom in designing an optical system increases, so that a stable structure can be designed.

A retro-reflector 13 may be used as the reflection optical element as shown in FIG. In the case of the mirror 11, it is difficult to adjust the position to reverse the optical path,
Since the retro-reflector 13 has the property of inverting the optical path in principle, the adjustment of the optical axis becomes easy.

Although the embodiment of FIG. 2 is described as a spatial beam, the parallel light portion may be guided by using an optical fiber 23 as shown in FIG. 4, for example. With such a configuration, the photodetector 8 and the DUT 7 can be separated from each other, so that the DUT 7 maintained at a high or low temperature can be measured.

The actuator 12 only needs to be able to change the reflection optical element in one direction, and may use PZT or a voice coil.

In the above embodiment, one point to be measured corresponds to one laser light source, so that scanning must be performed in order to measure the entire object to be measured. Have difficulty. In order to solve this problem, as shown in FIG. And a spatial filter array 15 having a plurality of pinholes facing the photodetector is arranged on the incident surface of the photodetector 8. What is necessary is just to make measurement light enter. With such a configuration, multi-point measurement can be performed simultaneously, so that high-speed measurement can be realized. And each acousto-optic element 3
Is easy to drive because the optical axis may be changed in a minute range. Further, by using the spatial filter array 15, the photodetector 8 can extract only the reflected light from the DUT 7 from which the harmonic components have been removed.
/ N ratio can be improved.

[0019]

As described above, according to the present invention, a confocal laser microscope capable of positioning an incident light beam in the depth direction of an object at a high speed can be realized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a confocal laser microscope of the present invention.

FIG. 2 is a configuration diagram showing another embodiment of the confocal laser microscope of the present invention.

FIG. 3 is a configuration diagram showing another embodiment of the confocal laser microscope of the present invention.

FIG. 4 is a configuration diagram showing another embodiment of the confocal laser microscope of the present invention.

FIG. 5 is a configuration diagram showing another embodiment of the confocal laser microscope of the present invention.

FIG. 6 is a conventional example of a confocal laser microscope.

[Explanation of symbols]

 Reference Signs List 1 laser light source 2, 6, 21, 22 lens 3 acousto-optic element (optical path control element) 4 drive circuit 5 half mirror 7 device under test 8 photodetector 9 polarization beam splitter 10 wavelength plate 11 mirror 12 actuator 13 retroreflector 14 pin Hole array 15 Spatial filter array 23 Optical fiber

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G02B 19/00-21/00 G02B 21/06-21/36

Claims (1)

(57) [Claims] 1. A laser light source, an optical path control element for changing an optical path of output light of the laser light source in a two-dimensional direction orthogonal to an optical axis, and a measurement for guiding the output light of the optical path control element to an object to be measured. In a confocal laser microscope provided with an optical system and a photodetector for detecting light to be measured from the object to be measured, the measuring optical system includes a beam splitting element, a reflecting optical element, and a light reflecting element. A confocal laser microscope comprising an actuator for displacing along an axial direction, and changing an optical path length between a laser light source and an object to be measured according to a position of a reflection optical element.