JPS6291802A - Observation measurement device - Google Patents

Abstract

PURPOSE:To measure continuously a state, a shape, etc., of an object to be inspected, by a simple constitution, by a color image reflecting means by a visible ray of an output of a color television camera, and a measuring signal extracting means of the object to be inspected, by a near infrared ray. CONSTITUTION:By an illuminating optical system consisting of an illuminating source 1, a wavelength cut filter 2, and a lens 3, a part to be inspected E is illuminated by a visible ray. Also, a measuring ray containing a near infrared ray from a light source 20 for measurement is projected to the part to be inspected E through an aperture 21, and a lens 22. On an optical axis of a objective lens 23 opposed to the part to be inspected E, a luminous flux distributor 24, a color television camera 26, etc., are placed, an output of the camera 26 is sent to color and monochromatic signal procesing circuits 27, 28 and an output of the circuit 27 is sent to a color 17. On the other hand, an output of the circuit 28 is calculated 29 and a desired measured value is obtained. Also, the distributor 24 deflects a part of a luminous flux from the lens 23 to an eyepiece 30 and also an inspector can observe visually the object to be inspected E through the lens 30.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention uses a television camera and a color monitor as a means of observation and measurement, and uses two-dimensional information using near-infrared light to determine the state, shape, etc. of an object. The present invention relates to an observation and measurement device that performs measurements.

[Prior Art] Various devices are known that capture an image of an object to be examined and make measurements using its two-dimensional information. explain.

FIG. 7 is a block diagram of a conventional operation keratometer, in which E is the eye to be examined and C is its cornea. Light from an illumination light source 1 made of, for example, a halogen bulb is irradiated onto the eye E through a wavelength cut filter 2 and a collimator lens 3. Here, the wavelength cut filter 2 has a characteristic of blocking light with a longer wavelength than near-infrared light and transmitting light with a shorter wavelength. Light reflected by the cornea C of the eye E to be examined is guided to a pair of stereoscopic optical systems via a large-diameter objective lens 5. The stereoscopic optical system is composed of relay lenses 6a, 6b and eyepieces 7a, 7b, and a guichroic lens is provided between the relay lens 6a and the eyepiece 7a and between the relay lens 6b and the eyepiece 7b, respectively. A mirror 8 and a light beam distributor 9 are inserted. The guichroic mirror 8 has a characteristic of reflecting light on the longer wavelength side than near-infrared light and transmitting light on the shorter wavelength side, and a measuring section is provided on the reflection side. In this measuring section, an imaging lens 10, a bandpass filter 11 that transmits near-infrared light, and a photoelectric converter 12 consisting of a two-dimensional solid-state imaging device such as a COD are arranged in this order. On the other hand, a color television camera 15 is provided on the reflection side of the light flux distributor 9 via an imaging lens 131 and a reflection mirror 14.
is arranged, and its output is recorded on a VTR 16 or displayed on a color monitor 17. Also,
A ring-shaped light source 18 made of a xenon flash discharge tube is provided in front of the objective lens 5, and serves as a projection optical system for photometry.

To explain the operation of the operation keratometer configured as described above, in FIG. 7, the ring-shaped light source 18 forms a reflected image R on the cornea C of the eye E to be examined. This reflected image R is formed as a projected image R° shown in FIG. 8 on the photoelectric converter 12 via the objective lens 5, the gicroic mirror 8, etc.

In this case, the ring-shaped light source 18 serving as the projection index may be one in which a plurality of light sources are provided on the circumference, or a ring-shaped slit may be provided in the optical path as the projection index. Here, since the cornea C is generally regarded as a toric surface, even if the ring-shaped light source 18 is a perfect circle, the corneal reflected image R will be an ellipse, and the projected image R' by the measurement optical system will also be an ellipse.

Projection image R' projected onto the photoelectric converter 12 shown in FIG.
and three scanning lines S1, S2 at appropriate intervals that cross this.
, S3, the intersection with the projected image R° S1°, S1″, S
2', S2'', S3', and 93'' are found. The corneal curvature of the eye E to be examined can be calculated by determining the elliptical shape of the projected image R' from the coordinates of five of these intersection points.

Generally, the equation of an ellipse is as follows for any coordinate axes x and y: ax2+by2+2cxy+dx+ey+ 1 = 0
It can be written as Here, since the five constants a-e are unknown, the shape of the ellipse on the plane is determined from the coordinates of the five points, and it is sufficient to use the minimum three tree scanning lines S1, S2, and s3. Become.

In FIG. 7, when the illumination light source 1 is turned on, among the light emitted from the light source 1, light in the visible wavelength range passes through the filter 2 and passes through the lens 3 to the corner 11! JC is uniformly illuminated. Corneal C
The scattered reflected light is subjected to a convergence effect by the objective lens 5, and is further imaged by each relay lens 6a, 6b. These images have balarax, and each image is different from each eyepiece 7.
Stereoscopic observation is performed through a and 7b.

At an appropriate time, when the ring-shaped light source 18 for measurement is turned on momentarily to illuminate the cornea C, the light reflected by the cornea C is converged by the objective lens 5 and the relay lens 6a. After that, when the dichroic mirror 8 reflects the light to the measurement section on the side, the light with a longer wavelength than the near-infrared light is reflected, and the imaging lens 10 forms a ring-shaped imaginary light source image on the photoelectric converter 12. Image R'. Of the light reflected by the cornea C,
Visible light with a shorter wavelength than near-infrared light passes through the dichroic mirror 8, so it does not reach the photoelectric converter 12, and even if some visible light is reflected by the dichroic mirror 8, it will not reach the bandpass filter 11. In addition, the long sleeve, curvature in the short axis direction, axis angle, etc. related to the corneal curvature, which are calculated based on the information detected by the photoelectric converter 12, will not become noise during photoelectric conversion. The value of can be displayed externally or internally to the device.

In addition, usually in order to record or transmit the details of the surgery,
An observed image equivalent to the image visually viewed by the examiner via the light flux distributor 9 and the color television camera 15 is recorded on the VTR 16 or presented on the color monitor 17F. In this case, when the ring-shaped light source 18 is turned on, a reflected image R is also formed on the imaging surface of the color television camera 15 as a projected image.

In this case, if it is possible to detect the projected image on the imaging surface of the color television camera 15 in the same manner as the projected image R' on the photoelectric converter 12, the dichroic mirror 8 of the measurement section described above, the imaging lens 10, bandpass filter 11, and photoelectric converter 12 are no longer necessary. However, since the conventional color television camera 15 is not sensitive to the near-infrared light region, the reflected image R of the ring-shaped light source 18 cannot be detected separately from the illumination light, and the light from the illumination light source 1 cannot be detected separately. However, in order to prevent this, it is possible to divide the time between measurement and observation, but this would interrupt the continuity of observation. Become.

For this reason, conventionally, this type of device requires two types of image receiving sections, namely a photoelectric converter for measurement 12 and a color television camera 15, which has the drawback of making the system very expensive, large, and complicated. be.

In addition, in this example of an operation keratometer, there are two visual optical systems for stereoscopic & observation, but the problem to be solved by the present invention is directly dependent on the presence or absence of the visual optical system or the stereoscopic observation system. This is unrelated and is a common shortcoming of devices that perform two-dimensional color observation and two-dimensional measurement of a test object.

[Object of the Invention] An object of the present invention is to perform an inspection of the object to be inspected using a color monitor, and to measure the condition, shape, etc. of the object by using two-dimensional information of the index projected onto the object. It is an object of the present invention to provide an observation and measurement device that is cheaper and has a simpler configuration than conventional ones.

[Summary of the Invention] The gist of the present invention for achieving the above-mentioned object is to provide an illumination means for illuminating a test object, and for projecting measurement light including light in the near-infrared region toward the test object. A projection means, an imaging means for forming an image of the object on an imaging section, and an imaging section that is sensitive to visible light and near-infrared light.・Separates visible light into three color wavelength ranges and generates near-infrared light. a color television camera equipped with a filter having a property of transmitting the color; a means for selectively inputting only light in the visible light region from among the luminous flux emitted from the illumination means and incident on the color television camera after passing through the object; It is characterized by comprising means for projecting a color image using visible light from the output of a television camera, and means for extracting a measurement signal of a test object using near-infrared light from the output of the color television camera and performing measurement processing. This is an observation and measurement device.

[Embodiments of the Invention] The present invention will be described in detail based on embodiments illustrated in FIGS. 1 to 6.

FIG. 1 is a configuration diagram of this embodiment, and the same reference numerals as in FIG. 7 indicate members having the same functions. As in FIG. 7, an illumination optical system consisting of an illumination light source 1, a wavelength filter 2, and an imaging lens 3 illuminates the test area E with visible light. Measurement light including near-infrared light is projected onto the test area E via the aperture 21 and lens 22. On the optical axis of the objective lens 23 facing the object E, there are arranged a light beam distributor 24, a filter 25 that can be inserted into and removed from the optical path, and a color television camera 26, and in front of the television camera 26. A solid-state image sensor 26a is attached to the portion, and three-color stripe filters 26b are arranged in a mosaic pattern in front of the solid-state image sensor 26a.

The output of the television camera 26 is sent to a color signal processing circuit 27 and a monochrome signal processing circuit 28, the output of the color signal processing circuit 27 is connected to the color monitor 17, and the output of the monochrome signal processing circuit 28 is connected to an arithmetic circuit 29. . Also,
A reciprocating lens 30 is arranged on the reflection side of the light flux distributor 24.

The reflected image of the aperture 21 by the illumination light source 1 and measurement light source 20 in the test area E is formed onto the image pickup element 26a of the television camera 26 by the objective lens 23. Objective lens 2
The light beam distributor 24 provided at the rear of the object lens 3 deflects a part of the light beam from the objective lens 23 to the eyepiece lens 30, so that the examiner can visually observe the object E through the eyepiece lens 30. It is.

The television camera 26 of this embodiment uses a single-tube type, and as described above, a three-color stripe filter 26b is installed in front of a solid-state image sensor 26a made of COD that is sensitive to visible light and near-infrared light. This color television camera is equipped with a color signal processing circuit 27 that forms a color image to obtain three channels of R, G, and H video signals. This signal is processed, for example, by NTSC conversion, as necessary, and the color monitor 17
The image of the object to be inspected is projected. Figure 2 (a), (b), (
c) illustrates the spectral characteristics of each of the three color filters constituting the stripe filter 26b, all of which have the characteristic of selectively transmitting visible light and transmitting all near-infrared light of 700 nm or more. The examples shown here are red, green,
These are the characteristics of the three colors of blue, but it is also possible to have complementary color characteristics.

Further, the output of the television camera 26 is sent to a monochrome signal processing circuit 28 that performs equivalent processing on each pixel of the image sensor, that is, outputs a monochrome signal for measurement without color signal processing corresponding to a three-color filter. and processing circuit 2
By calculating the output of 8 by the calculation circuit 29,
It is possible to obtain desired measured values.

If the present invention is applied to the operation keratometer described in the conventional example, the monochrome signal processing circuit 28 corresponds to the means for extracting the three scanning lines S1, S2, and S3 in FIG. In this embodiment, a solid-state image sensor 26a is used as an image sensor.
The reason for using this is that it is relatively easy to extract the above-mentioned signal. The filter 2 arranged in the illumination optical system is a near-infrared light cut-visible light transmission filter, and its characteristics are shown by B in FIG.

Next, to explain the operation of this embodiment, in the a detection state, the illumination light emitted from the illumination light source 1 has a visible light component only due to the action of the filter 2. The image is separated into colors, and the color signal processing circuit 27 outputs R, G, and B video signals, and a color image of the subject E is displayed on the color monitor 17.

Furthermore, due to the characteristics of the stripe filter 26b disposed in front of each pixel, the monochrome signal processing circuit 28 that outputs the measurement monochrome signal outputs a weak signal due to selectively transmitted light.

Here, a measurement light source 2 having sufficient light intensity in the near-infrared light region is used.
0, a reflected image of near-infrared light from the ring-shaped aperture 21, for example, is formed on the image sensor 26a. This state is also displayed on the color TV monitor 17, but since each pixel is processed equally in the monochrome signal processing circuit 28, the resolution is higher than that of the scanning line on the color TV monitor 17. It will be detected in the same state.

In this case, the problem of the S/N ratio between the reflected image of near-infrared light and illumination light of only visible light is generally solved by (1) image sensor 2
The spectral sensitivity of each pixel constituting 6a has a peak in the near-infrared region as shown in Figure 4, and (2) the light-emitting element can easily have a large output in the near-infrared region. It is easy to obtain a sufficient S/N ratio by considering the following three points: (3) visible light illumination light is attenuated by the three-color stripe filter 26b.

From the above, it is possible to carry out measurements while maintaining the continuity of both television and visual observation in the unimplemented examples. Now, if continuity of TV viewing is not required, this S/ The problem of the N ratio is completely solved, it is possible to keep the output of the measurement light source 20 low, and furthermore, the output of the image sensor 26
For a, a type with a narrow tolerance range for the amount of incident light can be used.

Further, the illumination light source 1 and the measurement light source 20 do not have to be provided separately, but may be used in common.

Furthermore, if the continuity of visual observation is not a problem, the illumination light and measurement light may be time-divided. It is clear that filters 2.25 may also be interchanged in position.

In any of the above cases, if the monochrome signal processing circuit 28 that outputs the monochrome signal for measurement is provided, higher resolution, that is, more accurate measurement is possible. On the other hand, there may be cases where only the continuity of observation is important and the accuracy of measurement is not so necessary. In this case, it is also possible to focus only on the advantage of being able to easily obtain a high S/N ratio as described above, and to use a normal color image signal as the measurement signal. In this case, the monochrome signal processing circuit 28 that outputs the measurement monochrome signal shown in FIG. Often, the device becomes simpler.

Note that the color television camera may be a three-tube type instead of a single-tube type. In this case, a color separation prism 31 is provided in front of each of the imaging tubes 26R, 26G, and 26B as shown in FIG. . The spectral transmittance of this prism 31 is shown in FIG.
), (b), and (c), the near-B infrared light IR enters the channel of the image pickup tube 26B. Therefore, the image pickup tube 26B may be used as the image pickup tube for monochrome measurement.

[Effects of the Invention] As explained above, the observation and measurement device according to the present invention enables observation and 411 measurement of a test object using a color television camera system, and is extremely simple and compact compared to conventional devices. It is possible to have the same or better performance. Furthermore, if the required performance is limited by various conditions, it is possible to reduce the cost and size by removing some of the components.

[Brief explanation of drawings]

The drawings show an embodiment of the observation and measurement device according to the present invention.
The figure shows its configuration, Figure 2 shows the characteristics of the three-color stripe filter, Figure 3 shows the characteristics of the filter for illumination observation, Figure 4 shows the characteristics of the spectral sensitivity of the image sensor, and Figure 5 shows the characteristics of the color TV camera. FIG. 6 is a characteristic diagram of a color separation prism, FIG. 7 is a diagram of a conventional operation keratometer, and FIG. 8 is an explanatory diagram of measurement processing. 2.25 is a filter, 17 is a color television monitor, 20 is a measurement light source, 21 is an aperture, 23 is an objective lens, 24 is a light flux distributor, 26 is a color television camera, 26a is an image pickup device, 26b is 3 Color stripe filters, 26R126G, 26B are image pickup tubes, 27 is a color signal processing circuit, 28 is a monochrome signal processing circuit, 29 is an arithmetic circuit, 30 is an eyepiece, and 31 is a color separation prism. Patent applicant Canon Co., Ltd. Figure 2 (G) (b'l (C) 3rd prisoner Rod 4 Figure 115 Figure 6m (G) (b> (C) 400 70 Onm

Claims (1)

[Claims] 1. An illumination means for illuminating the test object, a projection means for projecting measurement light including light in the near-infrared region toward the test object, and an imaging unit for directing the test object to the imaging section. An image forming unit that forms an image, an imaging unit that is sensitive to visible light and near-infrared light, and a color filter that separates visible light into three color wavelength ranges and has a filter that transmits near-infrared light. a television camera, a means for selectively inputting only light in the visible light range from among the luminous flux emitted from the illumination means and incident on the color television camera via the object; and a color image using visible light from the output of the color television camera. 1. An observation and measurement device comprising: means for displaying an image; and means for extracting a measurement signal of an object using near-infrared light from the output of the color television camera and performing measurement processing. 2. The observation and measurement device according to claim 1, wherein the means for selecting light in the visible light region is illumination means having a light source having a light emitting region only in the visible light region. 3. The observation and measurement device according to claim 1, wherein the means for selecting light in the visible light region is a visible light transmission/near-infrared light cut filter provided within the illumination means. 4. The observation and measurement device according to claim 1, wherein the means for selecting light in the visible light region is a visible light transmitting/near-infrared light cutting filter that is insertably provided in the imaging means. . 5. The observation and measurement device according to claim 1, wherein the illumination means and the projection means can be used in common. 6. The observation and measurement device according to claim 1, wherein the color television camera is a single-tube type, and the filter provided in the television camera is a three-color stripe filter arranged in a mosaic pattern. 7. A processing circuit that forms a color image from the output of the image sensor, and a processing circuit that performs equivalent processing on pixels behind the three-color stripe filter of the image sensor and outputs a monochrome signal for measurement. An observation and measurement device according to claim 1. 8. The observation and measurement device according to claim 1, wherein a light flux distribution means is provided in the imaging means so that the object to be inspected can be visually observed.