JPH0629712B2 - Projection inspection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a projection inspection apparatus that projects an image-forming light beam from a projection lens onto a screen via a reflecting member.

(Background of the Invention) Conventionally, the most general method for measuring the shape of a complicated two-dimensional object is to measure the coordinates of each point by using a stage with a factory microscope or a projection inspector, and to perform calculation. Find the shape. This method enables digital measurement by using an encoder or the like, and by processing the output with a computer or the like, it becomes possible to immediately obtain information on a complicated shape. In such a measurement, the projector has only the function of pointing to the measurement point of the object, but the wide field of view of the projector is very convenient for grasping the position of the measurement point in the whole. Furthermore, it has the advantage that it is easier to observe than a factory microscope and does not get tired of long-time measurements.

There is a position detecting device retrofitted to the screen to further utilize the advantage of such a projector. This is to improve the accuracy by eliminating the personal error that occurs when the crosshairs of the screen and the measurement points are matched, and further to shorten the detection time of the measurement points and improve the efficiency, as in JP-A-59-162404. Things have been known for a long time.

However, in the above-mentioned conventional example, since the diameter of the position detecting device retrofitted to the surface of the screen is about 10 mm, the area where the position detecting device is attached is covered on the screen, and the measurement point is slightly unclear. It became clear, the measurement was difficult, and the error was likely to occur due to the deviation of the measurement points in the measurement of complicated shapes. In addition, when performing comparative measurement using a chart, which is still an important measurement method, as a measurement of a complicated shape that is insufficient as a measurement of the representative point alone, use the position detection device on the screen surface. There is a problem that it is very troublesome to attach and detach the position detecting device as needed.

As a conventional projection inspection apparatus aimed at improving such problems, there is, for example, the one shown in FIG.

The conventional projection inspection apparatus with a built-in position detection device shown in FIG. 5 is arranged between the projection lens 1 and a reflecting member 3 that reflects the image-forming light flux from the projection lens 1 to the screen 2. By disposing another reflecting member 4 for reflecting the image-forming light beam on the reflecting member 3 and making a part of the reflecting member 4 a semi-transmissive surface, the image-forming light beam from the projection lens 1 is divided into two, The position detecting device 5 is arranged on the transmitted light path of the reflecting member 4.

However, in the conventional example shown in FIG. 5, when the reflecting member 4 is a semi-transmissive surface, the reflecting member 4 is arranged obliquely with respect to the optical axis of the projection lens 1. There is a problem in that the light beam that passes through and is incident on the position detecting device 5 has an aberration, and this aberration adversely affects the position detection accuracy of the position detecting device 5.

Further, as another conventional example of the projection inspection apparatus which solves the conventional problems disclosed in Japanese Patent Laid-Open No. 59-162404, there is one shown in FIG.

The conventional projection inspection apparatus shown in FIG. 6 divides the image-forming light flux from the projection lens 1 into two by the half mirror 6, detects the reflected light of the half mirror 6 on the screen 2, and detects the transmitted light of the half mirror 6 in position. It is configured so as to lead to the devices 5, respectively.

However, in the conventional example shown in FIG. 6, since it is necessary to send a considerable amount of light also to the position detecting device 5 side, the amount of light sent to the screen 2 side is reduced and the brightness on the screen 2 is lowered. As a result, it cannot be used in a relatively bright atmosphere, and since the image-forming light beam between the projection lens 1 and the screen 2 is very thick, a large half mirror 6 is required, It is difficult to make such a large half mirror 6 with high precision, and it is difficult to make the half mirror 6 thick in order to avoid the occurrence of a double image or the like. Therefore, it is difficult to hold the half mirror 6. There was a problem.

(Object of the Invention) The present invention has been made in view of such conventional problems, and can sufficiently secure the brightness on the detection element without substantially reducing the brightness on the screen. It is therefore an object of the present invention to provide a projection inspection apparatus which can be used in a relatively bright atmosphere, can be measured quickly, and has good operability.

(Summary of the Invention) The gist of the present invention for achieving such an object is to provide a projection inspection apparatus for projecting an image-forming light beam from a projection lens onto a screen via a reflecting member, between the projection lens and the screen. , A light beam splitting prism having a semi-transmissive surface formed on the cemented surface, the reflecting member and the screen are placed on the transmitted light path of the light beam splitting prism, and a detection element is provided on the reflected light path of the light beam splitting prism. And a converging lens that forms an image on the detection element at a magnification smaller than the projection magnification on the screen of the light flux reflected by the light flux splitting prism.

Further, in the projection inspection apparatus, the converging lens arranged on the reflection optical path forms an image of the light beam reflected by the light beam splitting prism on the detection element at a magnification smaller than the projection magnification on the screen. Therefore, the illuminance of the reduced image is increased, and even if the division of the light amount into the detection element is reduced, the illuminance sufficient to operate the detection element can be obtained. Therefore, a sufficient amount of light to the screen can be secured.

(Embodiment) Each embodiment of the present invention will be described below with reference to the drawings.

1 and 2 show a first embodiment of the present invention.

A projection inspection apparatus 10 shown in FIG. 1 includes a roof prism 30, a light beam splitting prism 4 and an imaged light beam from a projection lens system 20.
0 and the mirror 50 to project on the screen 60.

A transmission illumination system 14 for transmitting and illuminating an object S to be measured placed on a stage 13 is incorporated in a base portion 12 of a main body 11 of the projection inspection apparatus 10.

An epi-illumination system 15 for epi-illuminating the object S to be measured via the projection lens system 20 is attached to the outside of the central portion of the main body 11.

The projection lens system 20 is attached to the main body 11 via a lens mount 16.

The light beam splitting prism 40 is arranged between the roof prism 30 and the mirror 50 in close proximity to the roof prism 30.

A mirror 50 is provided on the transmitted light path A of the light beam splitting prism 40.
A screen 60 is arranged, and an edge detection element 70 and an edge detection of the light beam reflected by the light beam splitting prism 40 on the reflected light path B of the light beam splitting prism 40 with a magnification smaller than the projection magnification on the screen 60. A converging lens 80 that forms an image on the element 70 is arranged. The edge detection element 70 is provided on the upper part of the projection inspection apparatus main body 11,
The reflected light path B intersects between the mirror 50 and the screen 60 on the transmitted light path A.

As shown in FIGS. 1 and 2, the light beam splitting prism 4
0 is formed by joining two wedge-shaped prisms 41 and 42.

The joint surface 43 of the two wedge prisms 41 and 42 is
The wedge prism 41 is formed so as to be a semi-transmissive surface, and the imaging light flux reflected by the cemented surface 43 is totally reflected by the incident surface 41a of the wedge prism 41.
Further, the wedge prism 41 has an exit surface 41b formed perpendicularly to the optical axis of the reflected light totally reflected by the entrance surface 41a.

The converging lens 80 for forming an image of the light flux emitted from the emission surface 41b on the edge detection element 70 is arranged at a position close to the emission surface 41b.

As described above, the converging lens 80 forms an image of the light beam reflected by the light beam splitting prism 40 and emitted from the exit surface 41b on the edge detection element 70 at a magnification smaller than the projection magnification on the screen 60. What did the edge detection element 7
The brightness on 0 is inversely proportional to the square of the magnification of the converging lens 80. Therefore, even if the light amount to the edge detecting element 70 side divided by the light beam splitting prism 40 is reduced, the edge detecting element 70 is This is to ensure that the brightness is sufficient for operation and to minimize the loss of the amount of light sent to the screen 60 side.

When the projection inspection apparatus 10 of the present embodiment is a projection inspection apparatus having a screen 60 having a diameter of 300 mm and a total projection system length of about 1200 mm, the magnification β of the convergent lens 80 is about +0.4. desirable. When the magnification β of the converging lens 80 is set to about +0.4, the brightness on the screen 60 can be reduced even if the transmittance of the joint surface 43 of the light beam splitting prism 40 is about 80% to 90%. The edge detecting element 70 can be sufficiently operated with almost no decrease.

The operation will be described below.

The object S to be measured illuminated by the transmissive illumination system 14 or the epi-illumination system 15 is imaged on the screen 60 by the projection lens system 20. The image-forming light beam from the projection lens system 20 is horizontally reversed by the roof prism 30 and is emitted toward the mirror 50 via the light beam splitting prism 40. A part of the image-forming light flux that has entered the light beam splitting prism 40 from the incident surface 41a is reflected by the cemented surface 43, and most of the light flux passes through the cemented surface 43.

The imaging light flux that has passed through the cemented surface 43 is emitted from the wedge prism 42 toward the mirror 50, and the imaging light flux reflected by the mirror 50 is projected as an erected image on the screen 60 and then on the screen 60. An enlarged projection image of the measured object S is formed. Here, as described above, since the transmittance of the bonding surface 43 is set to about 80% to 90%, the loss of the amount of light sent to the screen 60 side is suppressed to the minimum, and the loss on the screen 60 is reduced. The brightness of the is almost unchanged.

On the other hand, the imaging light flux reflected by the cemented surface 43 is totally reflected by the entrance surface 41a of the wedge prism 41, and the exit surface 41b.
Is ejected from the lens toward the convergent lens 80. The convergent lens 80 reduces the image-forming light flux from the exit surface 41b by a small magnification of about +0.4, and forms an image on the edge detection element 70. Here, the transmittance of the bonding surface 43 is 80% to 90%.
Since it is set to a certain level, the amount of light split by the light beam splitting prism 40 toward the edge detection element 70 side is small,
Since the brightness on the edge detecting element 70 is inversely proportional to the square of the magnification of the convergent lens 80, the edge detecting element 70 has
An image of sufficient brightness is formed for the edge detection element 70 to operate, that is, 1 / β ² due to the reduction ratio β = 0.4.
= 1 / (0.4) ² = 6.25 times as bright.

In the above-described embodiment, the edge detecting element 70 is arranged above the main body 11 by removing it from the light flux to the screen 60, and the effective use of the space is achieved by the edge detecting element 7.
0 may be arranged on the left side or the right side of the main body 11 when the screen 60 is viewed from the front, and the light flux from the converging lens 80 may be bent by the reflecting member and guided to the edge detecting element 70. Good.

Regarding the mounting position of the light beam splitting prism 40, when the lens mount 16 is of the turret type, there is no spatial margin, so the light beam splitting prism 40 is placed between the roof prism 30 and the mirror 50. It is most desirable to dispose, but when the lens mount 16 is not of the turret type, it is possible to dispose the light beam splitting prism 40 in a place other than the above because there is a spatial margin.

Next, a second embodiment of the present invention will be described.

3 and 4 show a second embodiment of the present invention. FIG. 3 is a configuration diagram in a plane including the incident surface of the light beam splitting prism 40, and FIG. 4 is a configuration diagram viewed from a direction of an arrow IV in FIG.

In the second embodiment, the image forming light beam reflected by the light beam splitting prism 40 is guided to the edge detecting element 70 and also to the focus position detecting system, and the other structures are the same as described above. It is similar to that of the first embodiment.

As shown in FIGS. 3 and 4, a beam splitter 90 is fixed to the exit surface 41b of the wedge-shaped prism 41 so as to divide the imaging light flux emerging from the exit surface 41b into two. The converging lens 80 is fixed to the exit surface of the beam splitter 90 on the transmission optical path side, and the imaging light flux reflected by the beam splitter 90 is attached to the exit surface of the beam splitter 90 on the reflection optical path side. Is fixed, and a converging lens 110 for focusing the focus position detecting system 100 on the focus position detecting element 101 is fixed.

Magnification β ′ of the convergent lens 110 is smaller than the magnification (β = + 0.4) of the convergent lens 80, and β ′ =
It is about +0.2 times. Therefore, even if the split ratio between the transmitted light and the reflected light of the beam splitter 90 is set to about 8: 2, the brightness on the in-focus position detection element 101 is almost the same as the brightness on the edge detection element 70.

Therefore, with such a configuration, also in the second embodiment, the transmittance of the joint surface 43 of the light beam splitting prism 40 can be set to about 80% to 90% as in the case of the first embodiment. Even if the detection element and the focus detection element are arranged, the brightness on the screen is hardly reduced.

The in-focus position detection system 100 converts the image forming light beam split by the beam splitter 90 into a prism 10 by a known method.
It is configured to detect the focus position by further dividing into two at 2 and causing an optical path difference, and extracting a high frequency component on the focus position detection element 101 at the pin position and the rear focus position.

In the projection inspection apparatus of the second embodiment having the above configuration, the image forming light flux reflected by the joint surface 43 of the light flux splitting prism 40 is totally reflected by the incident surface 41a of the wedge prism 41 and emitted from the exit surface 41b. Then, the beam splitter 90 divides the light into a transmitted light and a reflected light.

The imaging light flux that has passed through the beam splitter 90 is reduced by the converging lens 80 and imaged on the edge detection element 70. On the other hand, the imaging light flux reflected by the beam splitter 90 is reduced by the converging lens 110, and is imaged on the focus position detection element 101 via the prism 102.

Also in this second embodiment, since the transmittance of the joint surface 43 is set to about 80% to 90%, the loss of the amount of light sent to the screen 60 side is suppressed to the minimum. The brightness on the 60 is almost unchanged.

On the other hand, the converging lens 80 and the converging lens 110 reduce the image-forming light beams split by the beam splitter 90 with a magnification smaller than that of the image formed on the screen 60, respectively, and detect the edge detecting element 70 and the focus position detecting element. Since the image is formed on 101, the edge detecting element 70, the focus position detecting element 101
A sufficient amount of light for operating the edge detecting element 70 and the focus position detecting element 101 is contained above.

The semi-transmissive surface formed on the joint surface 43 of the light beam splitting prism 40 may be formed uniformly over the entire joint surface, or may be a partial semi-transparent surface for reflecting light only in a part of the optical path. It may be a transparent surface. Even in the case of a partial semi-transmissive surface, the transmittance on this surface is maintained at 80 to 90%, so that there is almost no peeling on the screen. Further, in the second embodiment, it is not necessary to bond the converging lens 80 and the converging lens 110 to the beam splitter 90 if there is a spatial margin.

Furthermore, the present invention is not limited to the above-described embodiments, and the focus position detection system 10 can be provided without the edge detection element 70.
It goes without saying that only 0 may be arranged on the reflected light path of the light beam splitting prism 40.

(Effect of the Invention) According to the projection inspection apparatus of the present invention, the imaging light beam reflected by the light beam splitting prism is imaged on the detection element by a converging lens at a magnification smaller than the projection magnification on the screen. , The brightness on the detection element can be sufficiently secured with almost no decrease in the brightness on the screen,
As a result, the device can be used in a relatively bright atmosphere, the measurement is easy, the measurement can be performed quickly, and the operability is good.

[Brief description of drawings]

1 and 2 show a first embodiment of the present invention. FIG. 1 is a schematic optical system layout showing a projection inspection apparatus, and FIG. 2 is an enlarged side view showing a main part. 3 and 4 show a second embodiment of the present invention, FIG. 3 is a side view showing a main portion, FIG. 4 is a view taken along the arrow IV in FIG. 3, and FIG. FIG. 6 is a schematic optical system layout diagram, and FIG. 6 is a schematic optical system layout diagram showing another conventional example. DESCRIPTION OF SYMBOLS 10 ... Projection inspection device 20 ... Projection lens system (projection lens) 40 ... Beam splitting prism 43 ... Bonding surface, 50 ... Mirror (reflection member) 60 ... Screen 70 ... Edge detection element (detection element) 101 ... Focus position detection Element (detection element) 80, 110 ... Converging lens A ... Transmitted light path of light beam splitting prism B ... Reflected light path of light beam splitting prism

Claims (1)

[Claims] 1. A projection inspection apparatus for projecting an imaged light flux from a projection lens onto a screen via a reflecting member, and a light flux having a semi-transmissive surface formed on a cemented surface between the projection lens and the screen. A splitting prism is disposed, the reflecting member and the screen are disposed on the transmitted light path of the light beam splitting prism, and the detection element and the light flux reflected by the light flux splitting prism are provided on the screen of the reflected light path of the light flux splitting prism. A projection inspecting apparatus, comprising: a converging lens that forms an image on the detection element at a magnification smaller than the projection magnification on the detection element.