JPS6355513A - Optical device - Google Patents

Abstract

PURPOSE:To improve the operability and the safety by illuminating a specific shape and keeping a peripheral work surface at a high lightness. CONSTITUTION:The luminous flux emitted from a bright field illuminating light source 1 is refracted at 90 deg. by a 45 deg. half mirror 2 in a barrel and is led to a surface 4 to be illuminated by a lens 3 and returns through the same optical path and passes the lens 3 again and is transmitted through the 45 deg. half mirror 2, and the image is formed on an image pickup device 5. When a light shielding plate 6 having a specific shape is arranged on the focal surface on the optical path, the image of this specific shape is formed (projected) on the surface 4 to be illuminated, and as the result, only a specific shaped part is illuminated. Besides this illuminating device, the luminous flux from an external illuminating light source 7 is allowed to pass a horizontal polarizing plate 8 and illuminates the surface 4 to be illuminated as a horizontally polarized light, and a vertical polarizing plate (horizontal polarized light and vertically polarized light have 90 deg. phase difference) is arranged on the optical path of image pickup to intercept the light so that the reflected light from the surface 4 does not reach the image pickup device 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to optical devices, such as visual inspection devices for printed circuit boards, microscopes, and the like.

[Conventional technology]

Conventionally, automatic visual inspection equipment has used a method of projecting a specific pattern onto the object to be detected and detecting a specific shape, but in this case, it is necessary to darken the surrounding area to detect the specific pattern image, making the work The disadvantage was that the performance was significantly reduced. Furthermore, there has been a bright field illumination method for microscopes and the like, and a technology for illuminating only the detection surface has been established. Note that an apparatus for inspecting external foreign substances such as semi-grooved wafers is disclosed in Japanese Patent Publication No. 59-4854, for example.
It is known from Publication No. 0.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION An object of the present invention is to provide an illumination optical device that is optimal for brightly illuminating a surrounding work surface while detecting a specific portion and improving the work environment.

[Means for solving problems]

An illumination device according to an embodiment of the present invention includes disposing a light-shielding plate with a specific shape (pattern) on the focal plane of the projection lens in the illumination optical system, and projecting this shape onto a surface to be illuminated to perform specific partial illumination. A horizontal polarizing plate is arranged in the external ambient general illumination to illuminate with horizontally polarized light, and a vertical polarizing plate is arranged in the image detection optical system to remove the external horizontally polarized illumination light (in this case,
(Horizontally polarized light refers to polarized light that is 90 degrees out of phase with each other), and by combining the two, it is possible to brightly illuminate the external surrounding work surface, and at the same time illuminate and detect only a specific shape. .

[Effect]

According to the above configuration, a specific portion of an object such as an inspection object or an am object is illuminated by a light shielding plate (illumination mask) having a specific shape. Therefore, an image in a specific range of the object can be observed with an eyepiece against a dark field background, or it can be displayed on a monitor television or the like using a video camera. On the other hand, when scanning an object horizontally, vertically, and horizontally, the illumination light that illuminates a wide area of the work surface or object is an optical system that does not reach the eyepiece or imaging device, so the projection surface is a dark field, It is now possible to illuminate a wide range of object surfaces.

In this way, the present invention was able to satisfy the contradictory demands of dark field and wide range illumination.

〔Example〕

The details of the present invention will be explained below with reference to the drawings.

FIG. 1 shows an overall configuration diagram of a specific shape detection illumination device to which the present invention is applied.

Here, a bright field illumination device is used for specific shape projection illumination, but this illumination system may be provided separately. The light beam emitted from the light source 1 for bright field illumination is refracted by 90 degrees by the 45'' half mirror 2 inside the lens barrel, sent to the illuminated surface 4 by the lens 3, returns along the same optical path, passes through the lens 3 again, This time, the image passes through the 45° half mirror 2 and is formed on the imaging device 5. In this case, the imaging device 5 may be an eyepiece for visual projection, etc. In this illumination system, the focal plane of the lens 3 is the same as that of the imaging device 5. In addition to being on the plane of
When a light shielding plate 6 of a specific shape is placed on the focal plane on this optical path,
This specific shape is imaged (projected) onto the illuminated surface 4, and as a result, only the specific shape portion is illuminated.

In addition to the above-mentioned illumination device, the light flux from the external illumination light source 7 is passed through a horizontal polarizing plate 8 to illuminate the illuminated surface 4 as horizontally polarized light. A vertically polarized light plate (having a phase difference of 90° from the horizontally polarized light) is arranged to block light.

When such an illumination device is used, the imaged (projected) result can detect only a specific shaped part as shown in Figure 2-(a), and the illuminated surface can be detected as shown in Figure 2-(b). It is possible to obtain uniform illumination as shown in the figure. For this reason, it is possible to detect a specific shape without darkening the surrounding area when using specific shape illumination such as local window or slit light illumination, improving work efficiency and detecting surrounding images using other optical devices. It has the advantage of being able to be processed as information.

Hereinafter, two examples of application of the device of the present invention will be explained using FIGS. 3 and 4.

FIG. 3 shows an application example in which a transmissive liquid crystal device is used and the pattern of a light-shielding plate of a specific shape is variable.

In FIG. 3, the light source 11 and the half mirror 14 correspond to the bright field illumination light source 1 and the 45° half mirror 12 in FIG. will be placed as an alternative. Here, the light beam sent out from the light source 11 passes through the transparent layer liquid crystal 12 and is irradiated onto the illuminated surface by the half mirror 14.

Now, if the lighting pattern of the transparent layer liquid crystal 12 is controlled by the liquid crystal lighting device 13, the light shielding shape changes, and the specific shape illumination pattern can be varied.

In this case, since the light beam passing through the transmissive liquid crystal is itself polarized, the polarizing plate used for external illumination is 90° out of phase with the light beam transmitted through the liquid crystal.

Figure 4 shows an example in which a light beam having a complementary color relationship is used instead of the 90° polarized light of the present invention. In this example, the surface to be illuminated is illuminated with complementary color light, although the workability in ambient illumination is reduced. , the projection itself can be obtained with high contrast.

FIG. 4 shows an illumination method that takes into consideration selective reflection of the background color.

In FIG. 4, a reflective surface 21, a low wavelength cut filter 2
3 and the long wavelength cut filter 25 are arranged at the positions of the illuminated surface 4, the horizontal polarizing plate 8, and the vertical polarizing plate 9, respectively, in FIG. The reflective surface 21 is colored in a certain manner, and its surface has characteristics such as reflective surface selective reflection characteristics 22 (wavelength-reflectance characteristics). Now, if we illuminate and project with wavelength components that are complementary colors to this selectively reflected light,
The brightness decreases on the reflective surface 21, and when there is a foreign object with other selective reflection characteristics on this surface, a high contrast projection can be detected.6 In this example, the low wavelength cut filter 23 has low wavelength cut filter characteristics. 24 (wavelength-transmittance characteristic) to illuminate the surrounding area, and a long wavelength cut filter 25 is installed in the projection optical system.
An image is projected using a long wavelength cut filter transmission characteristic 26 (wavelength-transmittance characteristic). Here, the bright field illumination system is arranged as in FIG. 1, and the relationship of complementary colors is not limited to this.

FIG. 5 shows the principle of the background color for realizing FIG. 4, in which a light beam condensed using a lens 31 is passed through a selective transmission filter 32 (this filter may also be placed in front of the lens 31).

Here, the selective reflection characteristics of the background 34 are shown in FIG. 5(d) (wavelength -
Figure 5 (C) shows the selective reflection characteristics of the foreign object 33.
(wavelength-reflectance characteristic), selective transmission filter 32
By setting the selective transmission characteristic as shown in FIG. 5(b) (wavelength-reflectance characteristic), the foreign matter 33 can be detected with high contrast.

〔Effect of the invention〕

According to the present invention, since the surrounding work surface can be kept at high brightness while illuminating a specific shape, work efficiency, safety, etc. can be improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the overall configuration of a lighting device using the present invention,
2 is a diagram showing the illumination effect of the device shown in FIG.
The figure shows another embodiment of the present invention in which light beams having complementary colors are used instead of 90° polarized light, and FIG. 5 is a diagram showing the principle of background color according to the present invention. 1... Light source for bright field illumination, 2... 45° half mirror 13... Lens, 4... Object to be illuminated (object to be inspected),
5... Imaging device, 6... Illumination mask, 7... Illumination device, 8... Horizontal polarizing plate, 7... Light source for external illumination 8... Horizontal polarizing plate 9... Keinao Polarizing plate Fig. 3 11... Light source 12... Transmissive liquid crystal 13... Liquid crystal lighting device 14... Half mirror c d

Claims (1)

[Claims] 1. A first illumination system that illuminates the object in a specific shape range, a second illumination system that illuminates the object through a first polarizing plate, and the first polarizing plate has a polarization axis. An optical device comprising: a projection system for projecting the object through a second polarizing plate that is arranged in a shifted manner.