CN100401009C - Long working distance interference microscope system - Google Patents

Abstract

The invention discloses a long working distance interference microscope system, comprising: a polarizer, a beam splitter, a long working distance microscope and a Wollaston prism formed by bonding two birefringent right-angle prisms whose optical axes are perpendicular to each other , the light source passes through the polarizer to form linearly polarized light, and after being reflected by the beam splitter, it passes through the Wollaston prism to split the incident linearly polarized light into two beams with a small angle and the vibration directions are perpendicular to each other Linearly polarized light, the two beams of light are projected onto the sample to be measured, and the two beams of orthogonal linearly polarized light reflected from the surface of the sample to be measured return through the original path, are recombined and collinear by the Wollaston prism, and pass through A quarter-wave plate forms elliptically polarized light, and then passes through an analyzer to form linearly polarized light with the same polarization direction. The invention is insensitive to external environments such as mechanical vibration, air disturbance, and temperature change, and its vertical measurement resolution reaches 50 nanometers, and has a working distance of more than 50 mm.

Description

Long working distance interference microscope system

technical field

The invention relates to an interference microscope system.

Background technique

Scientific problems in many disciplines have put forward higher and higher demands on micro-scale measurement technology. Micro-scale measurement technology can no longer meet the needs of scientific development. The research on nano-scale measurement technology has become the goal that the field of metrology strives to achieve. . Existing high-precision micro-scale measurement technologies such as atomic force microscopes and scanning tunneling microscopes can provide high measurement accuracy, but they are very sensitive to external environments such as mechanical vibration, air disturbance, and temperature changes, and are contact measurements. , the scope of application is limited.

Contents of the invention

In view of the above existing problems, the object of the present invention is to provide a long working distance interference microscope system, which can realize quantitative measurement at the nanometer scale.

In order to achieve the above purpose, a long working distance interference microscope system is invented, including: a polarizer, a beam splitter, a long working distance microscope and a Wollas bonded by two birefringent rectangular prisms whose optical axes are perpendicular to each other. Wollaston (Wollaston) prism, the light source forms linearly polarized light through the polarizer, and then passes through the Wollaston prism after being reflected by the beam splitter, and the incident linearly polarized light is divided into two beams with a small angle and Linearly polarized light with vibration directions perpendicular to each other. The two beams of light are projected onto the sample to be measured, and the two beams of orthogonal linearly polarized light reflected from the surface of the sample to be measured return through the original path and are recombined by the Wollaston prism. Collinear, and pass through a quarter-wave plate to form elliptically polarized light, and then pass through an analyzer to form linearly polarized light with the same polarization direction, interference occurs, and the image signal is received by a long working distance microscope and a CCD camera, and then transmitted Perform image acquisition and processing on a computer equipped with image processing software.

The invention adopts the non-contact surface topography optical measurement technology, which combines interference technology, long working distance microscope technology, image acquisition and processing technology, phase shift technology, etc., to realize the quantitative measurement of nanoscale. The invention is not sensitive to external environments such as mechanical vibration, air disturbance, and temperature changes, and its vertical measurement resolution reaches 50 nanometers, with a working distance of more than 50mm, and can observe details that are difficult to distinguish by ordinary optical microscopes. Applicable to various disciplines.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the present invention.

Fig. 2 is a real photo of a flat crystal and a dielectric film detected by the present invention.

Figure 3 shows the four-step phase shift interference fringes on the flat crystal surface.

FIG. 4 is a surface topography diagram of FIG. 3 .

Figure 5 shows the interference fringes on the surface of the dielectric film.

Figure 6 shows the sum of the surface deformation of the dielectric film and the basic deformation of the Wollaston prism.

FIG. 7 is a surface topography diagram of the dielectric film in FIG. 6 .

Figure 8 and Figure 9 are the results of measuring the surface of the dielectric film by the atomic force microscope.

Detailed ways

As shown in Fig. 1, the present invention includes: polarizer 2, magnifying glass 3, beam splitter 10, long working distance microscope 7 and Wollaston formed by bonding two birefringent right-angle prisms whose optical axes are perpendicular to each other. (Wollaston) prism 5, the light source 1 forms linearly polarized light through the polarizer 2, is amplified by the magnifying glass 3 and reflected by the beam splitter 10, and then passes through the Wollaston prism 5, and the incident linearly polarized light is divided into two beams with tiny The two beams of linearly polarized light with angles and vibration directions perpendicular to each other are projected onto the sample 11 to be measured, and the two beams of orthogonal linearly polarized light reflected from the surface of the sample to be measured return through the original path and are passed by the Wollaston prism 5 recombines collinearly, and is reflected by the reflector 4 again, passes through a quarter-wave plate 6 to form elliptically polarized light, and then passes through an analyzer 9 to form linearly polarized light with the same polarization direction, interference occurs, and passes through a long working The microscope 7 and the CCD camera 8 receive the image signal, and then transmit it to the computer 12 provided with image processing software for image processing, and a ground glass 13 is arranged between the long working distance microscope 7 and the CCD camera 8, so that the CCD camera 8 collects images. The computer 12 calculates and restores the image through traditional image processing methods, namely Fourier transform method and four-step phase shift method, and restores the interference image to a surface topography map.

As shown in Figure 2, it is a photo of flat crystal and dielectric film detected by the present invention, as shown in Figure 3, it is a four-step phase shift interference fringe on the flat crystal surface of Figure 2, and Figure 4 is a surface profile diagram of Figure 3 , Fig. 3 and Fig. 4 show the interference fringes and surface topography diagrams of the flat crystal surface respectively, which represent the basic fringes produced by the Wollaston prism. The sum of the basic deformation of the prism, Figure 7 is the surface topography of the dielectric film in Figure 6, Figure 8 and Figure 9 show the results of the surface of the dielectric film measured by the atomic force microscope, the maximum deformation is 52nm, indicating that the interference microscope can achieve the measurement of 50 nm deformation .

Claims (1)

1. long working distance interference microscope system, it is characterized in that, comprise: the polarizer, beam splitter, long working distance microscope and the wollaston prism that is bonded by two mutually perpendicular birefringence right-angle prisms of optical axis, light source forms linearly polarized light through the described polarizer, amplify by magnifier, and behind described beam splitter reflection again by described wollaston prism, incident ray polarized light is divided into two bundles has small angle and the mutually perpendicular linearly polarized light of direction of vibration, this two-beam projects on the measured sample, return through former road from two bundle orhtogonal linear polarizaiton light of measured sample return reflection surface, by the compound again conllinear of described wollaston prism, and through quarter-wave plate formation elliptically polarized light, again through forming the identical linearly polarized light in polarization direction behind the analyzer, interfere, receive picture signal by long working distance microscope and CCD camera, be transferred to the computing machine that is provided with image processing software again and carry out Flame Image Process, be provided with a frosted glass between long working distance microscope and the CCD camera, the long working distance microscope at first outputs to picture signal on the frosted glass, and then carries out image signal's collection by the CCD camera.

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