JPH06273232A - Light intercepting optical system for colorimeter - Google Patents

Abstract

PURPOSE:To provide a light intercepting optical system which can effectively lead the light, which is to be measured and uniformly contains light beams emitted from respective points in an area to be measured, to respective sensors of a sensor array so that the light to be measured is incident on a filter face vertically in a light intercepting optical system of a colorimeter using a spectral sensor consisting of a combination of a wavelength resolving filter and a sensor array and the like. CONSTITUTION:Light emitted from an area to be measured passes an aperture 2, an objective lens 3, and an aperture 4 and extends radially in the rear side beyond an image forming position. A spectral sensor consisting of a wavelength resolving filter 5 and a sensor array 6 is arranged inside an area, in which light beams emitted from all the points in the area to be measured are contained necessarily, and uniformity of the incident light is maintained. Light beams from the area to be measured 1 are converged in the vertical direction to a row of the sensor array by a cylindrical lens 7, so that light intercepting effect is improved comparing with a conventional optical system. On the other hand, the light beams from the area to be measured 1 are converted into parallel light beams after passing through a cylindrical lens 8, so that the light beams are incident on the filter 5 vertically.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention utilizes a spectral sensor composed of a combination of a wavelength decomposing filter for decomposing incident light into respective wavelength components and a sensor array such as a CCD, and as a color information of measured light, The present invention relates to an optical system for guiding light from a region to be measured to a spectroscopic sensor and irradiating the device in a device that outputs a wavelength component (a spectrophotometer, a spectrophotometer, etc.)

[0002]

2. Description of the Related Art At present, a so-called colorimeter, which is a device for measuring the color of light from a certain light source or the color of an object, is widely used in the field of color management of products and products. A colorimeter generally includes an optical system for efficiently guiding light from a predetermined measurement area to a spectroscopic sensor.
The optical system of this colorimeter should ideally satisfy the following conditions.

(1) The light incident on each element of the sensor array must uniformly include color information of all parts of the measured region. (2) The intensity of light incident on each element of the sensor array is almost uniform. (3) To efficiently guide the light from the measured region to each element of the sensor array. (4) When a continuous interference filter is arranged on the front surface of the sensor array, the light incident on the continuous interference filter must be parallel light that is perpendicular to the filter surface. Among the above conditions, (4) is a condition for optimizing the wavelength resolution characteristic of the continuous interference filter. If this condition is not satisfied and oblique light is incident on the filter surface,
The following characteristic defects occur.

The central transmission wavelength of the incident point of light is shifted to the short wavelength side. The half-width becomes wider. The transmittance in the wavelength range that should be the non-transmissive wavelength range becomes high. In the case of a filter with a structure that obtains synthetic transmission characteristics by combining multiple continuous interference filters deposited on individual glass substrates, the light obliquely incident on the filter surface is reflected multiple times between the filters and is incident. You get lost in the sensor side from the position where the transmission wavelength is different from the point. Therefore, there arises a disadvantage that a wavelength that should originally be an opaque wavelength is transmitted.

FIG. 6 shows an optical system of a general colorimeter which has been widely used conventionally. 10 in the figure
Reference numeral 1 represents a measured region. Reference numerals 102 and 104 denote apertures that determine the boundaries of the measured region and also determine the maximum deflection angle from the optical axis of the light beam that passes through the objective lens 103 from within the measured region. When the boundary of the measured region must be set strictly, the aperture 104 is arranged at the image forming position of the measured region by the objective lens 103, and the aperture diameter is made to match the image of the boundary of the measured region. Good.

Reference numeral 105 denotes a wavelength separation filter for separating incident light into respective wavelength components, and reference numeral 106 denotes the filter 105.
3 shows the sensor array placed after the. A known photoelectric conversion element such as a silicon photodiode array or a one-dimensional CCD sensor is used for the sensor array 106.
The combination of the filter 105 and the sensor array 106 constitutes a spectroscopic sensor.

The light emitted from the area to be measured 101 is an aperture 102, an objective lens 103, and an aperture 1.
04, and spreads radially behind the imaging position. Then, as the distance from the image formation position increases, "a region that always includes light rays emitted from all points in the measured region"
Spreads. In the optical system shown in FIG. 6, the filter 1
Since the spectroscopic sensor including the sensor 05 and the sensor array 106 is arranged in this region, the light rays emitted from all the measurement points in the measured region are incident on any of the sensor elements in the sensor array 106. To be done. With this configuration, the above condition (1) that "light incident on each element uniformly includes color information of all portions of the measured region", and
It is possible to satisfy the condition (2) that "the intensity of light incident on each element is substantially uniform."

In FIG. 6, the ray indicated by the dotted line indicates the range of the ray bundle emitted from the center of the measured area, and the ray indicated by the solid line indicates the range of the ray bundle emitted from one point on the boundary of the measured area. Indicates. The dotted circle on the right side shows the irradiation range on the light receiving surface of the array sensor due to the ray bundle from the center of the measured area.The solid circle indicates the ray bundle from the point on the boundary of the measured area. Shows the irradiation range.

As can be seen from the figure, of the light within the circle that is the irradiation range, only a small portion is actually incident on the sensor array 106, and most of the light is emitted outside the sensor array. . That is, in the optical system shown in FIG. 6, most of the light rays emitted from the measured region 101 are not used. Moreover, as can be seen from the deviation of the irradiation range of the ray bundle from the center of the measured area and the irradiation range of the ray bundle from the point on the boundary, "it is emitted from all points in the measured area". The "region in which the light beam is necessarily included" is limited to a portion where the irradiation ranges of the light beam bundles from the respective points overlap. Therefore, the light from the measured region cannot be collected any more.

Further, in the optical system of FIG. 6, light is incident in the vicinity of the center of the wavelength resolving filter 105 perpendicularly to the filter surface, but the incident angle of the light beam becomes closer to both ends away from the center. Becomes large, and light is obliquely incident on the filter surface. As a result, the above-mentioned problems (1) to (3) occur near both ends of the spectroscopic sensor.

As described above, in the optical system of FIG.
Of the above conditions required for the optical system of the colorimeter, (3)
It is not possible to satisfy "to efficiently guide the light to be measured to the sensor array" and (4) "the light incident on the filter is parallel light perpendicular to the filter surface".

Next, FIG. 7 shows another conventional example and shows an optical system of a colorimeter disclosed in Japanese Patent Laid-Open No. 62-177422. In FIG. 7, the same components as those in FIG. 6 are designated by the same reference numerals.

In the optical system of FIG. 7, the objective lens 10
The condenser lens 107 is arranged so that the image of the exit pupil of No. 3 is formed on the surface of the sensor array 106.
With this configuration, the irradiation range of the light flux emitted from the center of the measured region indicated by the dotted line and the irradiation range of the light flux emitted from the point on the boundary of the measured region indicated by the solid line match. That is, the irradiation range of the ray bundles from all the points in the measured region 101 coincides with the solid line circle shown on the right side, and this circle indicates that "the rays emitted from all the points in the measured region must be It becomes the “included area”. Therefore, as compared with the optical system of FIG. 6, it is possible to further collect the light from the measured region and guide the light more efficiently.

However, the sensor array 1 still remains.
Only a small part of the light within the circle of the irradiation range is incident on 06, and most of the light from the measured region is not used. Further, there is no improvement in the point that light is obliquely incident on the filter surface as it approaches the both ends of the filter. Thus, even in the optical system of FIG.
The above conditions (3) and (4) are not satisfied.

As another conventional example, Japanese Laid-Open Patent Publication No. 4-2.
No. 23236 is known. This Japanese Patent Laid-Open No. 4-2322
The optical system of the colorimeter disclosed in No. 36 is basically the same as that shown in FIG. 7, but an optical fiber bundle is newly provided for guiding light to the spectroscopic sensor. One end of this optical fiber bundle is arranged at the position of the light receiving surface of the array sensor 106 in FIG. 7, and the other end is arranged immediately before the spectroscopic sensor.

In this optical system, since the end surface of the optical fiber bundle and the light receiving surface of the spectroscopic sensor are relatively close to each other, the light receiving efficiency of the measured light on the light receiving surface of the spectroscopic sensor is improved as compared with the optical system of FIGS. Has been done. However, the light incident on the sensor array 106 is still a part of the whole. Further, since the end surface of the optical fiber bundle and the light receiving surface of the spectroscopic sensor are close to each other, light is incident on both ends of the filter at an angle.

As described above, in any of the conventional examples, an optical system that satisfies the above conditions (1) and (2) for the uniformity of incident light and also satisfies the condition (3) or (4). Has not been realized.

[0018]

By the way, conventionally, as a wavelength resolution filter of a spectroscopic sensor, for example, a three-layer structure thin film made of "silver / magnesium fluoride / silver" formed on a glass substrate by vacuum deposition, etc. Filters with a relatively small number of layers have been widely used. Note that the layer sandwiching magnesium fluoride is a layer that functions as a mirror, and may be any metal having a high reflectance, and is not limited to silver. (There are also examples of aluminum, gold, etc.) Since such a filter is relatively easy to miniaturize, it is possible to realize a compact spectroscopic sensor. However, since the filter as described above uses a metal film, it has problems such as storage temperature limitation and protection against oxidation of the metal film, and also has a problem regarding wavelength resolution accuracy. .

On the other hand, in recent years, a dielectric multilayer filter has been proposed in which each layer of a high refractive index layer and a low refractive index layer of a dielectric is alternately deposited in a wedge shape on a multi-layer glass substrate.
This dielectric multilayer filter does not have the above-mentioned problems such as storage temperature and metal oxidation, and is excellent in environmental resistance.
Moreover, the wavelength resolution accuracy is also superior to that of the filter. However, it is difficult to reduce the spectral pitch of the dielectric multilayer filter due to its structure, and it is impossible to downsize it to the same size as a conventional filter. Therefore, when the spectroscopic sensor is constructed using the dielectric multilayer filter, it becomes considerably larger than the conventional one.

When a spectroscopic sensor using this dielectric multilayer film filter is mounted on a colorimeter, the size of the sensor increases,
It is necessary to secure more measured light. However, in order to increase the amount of light to be measured, it is necessary to increase the area of the region to be measured and the lens diameter of the optical system, resulting in an increase in size of the device. Therefore, it is necessary to more efficiently guide the light from the measured region to the spectroscopic sensor than ever before.

Further, as the size of the spectroscopic sensor becomes larger, the incident angle of the light ray incident on both ends of the filter becomes larger, and the problem (above-mentioned) due to the light ray obliquely incident on the filter surface increases.

As described above, in order to mount the dielectric multi-layer film filter on the colorimeter, the problems of "light receiving efficiency of the light to be measured" and "problems of incident angle of light rays on the filter" are solved more than ever before. There is an urgent need to realize an optical system that satisfies the above conditions (3) and (4).

Therefore, the object of the present invention is to solve the above-mentioned problems, to satisfy the conditions of "uniformity of incident light" in the above (1) and (2), and to add to the "measured area" in (3). To provide an optical system of a colorimeter that satisfies the condition that "light from the sensor is efficiently guided to the sensor" or the condition that (4) the light that enters the filter is parallel light that is perpendicular to the filter surface. It is in.

[0024]

In order to achieve the above object, a light receiving optical system of a colorimeter of the present invention has a curvature in a direction perpendicular to a column of a sensor array and passes through an exit pupil of an objective lens. It is characterized in that it is provided with a cylindrical lens 7 for forming an image of only the direction component of the ray of light which is perpendicular to the column of the sensor array in the vicinity of the sensor array surface. (Claim 1) In a light receiving optical system of a colorimeter of another invention, in addition to a cylindrical lens having a curvature in a direction perpendicular to a row of the sensor array, a light receiving optical system is provided near an image forming surface of an area to be measured by an objective lens. It is characterized in that it is provided with a cylindrical lens 19 which is arranged and has a curvature in a direction parallel to a row of the sensor array. (Claim 3) In a light receiving optical system of a colorimeter of another invention, in addition to the cylindrical lens having a curvature in a direction perpendicular to the row of the sensor array, a rear side of an image forming position of an area to be measured by an objective lens is provided. It is characterized in that it is provided with a short focus lens 32 arranged in the vicinity thereof and a diffusion plate 33 arranged at a position where a ray bundle behind the short focus lens converges. According to a fifth aspect of the present invention, in a light receiving optical system of a colorimeter of the present invention, in addition to a cylindrical lens having a curvature in a direction perpendicular to a row of the sensor array, an objective lens is provided behind an imaging position of an area to be measured. It is characterized in that it is provided with a short-focus lens 52 arranged in the vicinity and an optical fiber 53 having an incident end face arranged at a position where a ray bundle behind the short-focus lens converges. (Claim 7) In a light receiving optical system of a colorimeter of another invention, a short focus lens 52 arranged near the rear of an image forming position of an area to be measured by an objective lens and an emitting end face have a ribbon shape. The optical fiber bundle 71 and a light shielding wall 72 that is arranged perpendicular to the rows of the sensor array and that restricts obliquely incident light to the wavelength resolution filter are characterized by being provided. (Claim 9) Furthermore, in the light receiving optical system of each of the above-mentioned inventions,
Further, a cylindrical lens having a curvature in a direction parallel to the row of the sensor array is provided near the front of the wavelength resolution filter.

[0025]

The light receiving optical system of the colorimeter of the present invention is provided with the cylindrical lens having a curvature in the direction perpendicular to the row of the sensor array, so that the light flux emitted from the measured region is perpendicular to the row of the sensor array. It is possible to collect light in different directions and make the irradiation range into an ellipse. Therefore, the light receiving efficiency is greatly improved as compared with the conventional optical system.

Further, by providing a cylindrical lens having a curvature in the direction parallel to the row of the sensor array in the vicinity of the front of the wavelength decomposing filter, it is possible to alleviate the problem that light rays are obliquely incident on the filter surface. it can.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment] FIG. 1 shows a first embodiment of the optical system of the present invention. The upper optical path diagram and the lower optical path diagram show the same optical system, and show optical paths in cross sections that include the optical axis and are perpendicular to each other. In FIG. 1, reference numeral 1 indicates a measured region. 2 and 4
Denotes an aperture, which determines the boundary of the measured region and also determines the maximum deflection angle from the optical axis of the light beam passing through the objective lens 3 from within the measured region. When it is necessary to strictly set the boundary of the measured region, the aperture 4 is arranged at the image forming position of the measured region 1 by the objective lens 3, and the aperture diameter is made to coincide with the image of the boundary of the measured region. Just go.

In this embodiment, the aperture 2 is arranged in front of and in contact with the objective lens 3 and the aperture 4 is arranged in the image forming position of the measured region by the objective lens 3, but this is merely an example. Nothing more. That is, in order to achieve the purpose of determining the boundary of the measured region and determining the maximum deflection angle of the light beam passing through the objective lens, an arrangement other than the above or the addition of an aperture is also possible.

Reference numeral 5 denotes a wavelength resolution filter for separating incident light into respective wavelength components, and 6 denotes a sensor array arranged after the filter 5. A combination of the filter 5 and the sensor array 6 constitutes a spectroscopic sensor.

The light emitted from the measured region 1 passes through the aperture 2, the objective lens 3, and the aperture 4, and spreads radially behind the image formation position. Then, as the distance from the image formation position increases, the region in which the rays emitted from all the points in the measured region are necessarily included spreads. In this embodiment, the spectroscopic sensor is arranged in this area,
The conditions (1) and (2) of “uniformity of incident light” described above are satisfied.

The lens 7 has a curvature in a direction perpendicular to the column direction of the sensor array, but has no curvature in a parallel direction.
It is a cylindrical lens. Cylindrical lens 7
Is arranged at a position where the image of the exit pupil of the objective lens 3 forms an image on the light receiving surface of the sensor array 6 in the direction perpendicular to the column direction of the sensor array having a curvature. In order to reduce the size of the device and design the distance from the objective lens 3 to the array sensor 6 to be short, a cylindrical lens having a short focal length may be used. However, the shorter the focal length, the shorter the distance between the cylindrical lens 7 and the sensor array 6, so that the incident angle of the light beam incident on the wavelength resolving filter 5 becomes large. (Because the light rays are obliquely incident.) As described above, if the focal length of the cylindrical lens 7 is too short, it causes various problems such as a shift of the transmission wavelength. Therefore, consider the relationship with the size of the device. You have to set an appropriate focal length.

The lens 8 has a curvature in a direction parallel to the column direction of the sensor array, but has no curvature in a vertical direction.
It is a cylindrical lens. Cylindrical lens 8
Is arranged such that the focal point thereof coincides with the position of the aperture 4 in the direction parallel to the column direction of the sensor array having a curvature. With this arrangement, the light beam that has passed through the aperture 4 becomes a light beam that is substantially parallel to the plane perpendicular to the column direction of the sensor array 6 after passing through the cylindrical lens 8.
Therefore, the problem of the conventional optical system that "the light rays are obliquely incident on both ends of the filter" is solved.

In FIG. 1, the ray indicated by the dotted line indicates the range of the ray bundle emitted from the center of the measured region, and the ray indicated by the solid line indicates the range of the ray bundle emitted from the point on the boundary of the measured region. . The dotted ellipse shown on the right side shows the irradiation range on the light receiving surface of the array sensor due to the ray bundle from the center of the measured area.The solid ellipse shows the ray bundle from the point on the boundary of the measured area. Shows the irradiation range.

As is apparent from FIG. 1, the light flux emitted from each point in the measured region 1 is condensed by the cylindrical lens 7 in the direction perpendicular to the column direction of the sensor array, and its irradiation range is It becomes an ellipse. Therefore, the ratio of the light rays that actually enter the sensor to the light rays that illuminate the sensor array becomes very high. Therefore, the light receiving efficiency is greatly improved as compared with the conventional optical system.

As described above, in the optical system of the first embodiment shown in FIG. 1, the above condition (3) "to efficiently guide the light to be measured to the sensor array" and (4) to the filter "The incident light is parallel light that is perpendicular to the filter surface."

[Second Embodiment] FIG. 2 shows a second embodiment of the optical system according to the present invention. In FIG. 2, the measured region 11, the apertures 12, 14, the objective lens 13, the wavelength resolving filter 15, and the sensor array 16 are the same as those in FIG.

The lens 17 is similar to the lens 7 of FIG.
Although there is a curvature in the direction perpendicular to the column direction of the array sensor,
The cylindrical lens has no curvature in the parallel direction, and is arranged at a position where the image of the exit pupil of the objective lens 3 is formed on the light receiving surface of the sensor array 16 in the direction having the curvature.

Each of the lenses 18 and 19 is a cylindrical lens having a curvature in a direction parallel to the column direction of the sensor array but no curvature in a vertical direction. The cylindrical lens 19 is arranged at a position where the image of the exit pupil of the objective lens 13 is formed slightly behind the light receiving surface of the sensor array 16. On the other hand, the cylindrical lens 18
Has a focal position that coincides with the position of the exit pupil of the cylindrical lens 19 and is arranged in front of the image position of the exit pupil of the objective lens 13 formed by the cylindrical lens 19. Furthermore, these two cylindrical lenses 18, 1
As the compound lens of 9, the image of the exit pupil of the objective lens 13 is formed on the light receiving surface of the sensor array 16. Therefore, the cylindrical lens 18 transmits the light rays that have passed through the cylindrical lens 19 and spread out.
It has a function of making light rays almost parallel to a plane perpendicular to the column direction of 6. Therefore, the problem of the conventional optical system that "the light rays are obliquely incident on both ends of the filter" is solved.

In FIG. 2, the ray indicated by the dotted line indicates the range of the ray bundle from the center of the measured area, and the ray indicated by the solid line indicates the range of the ray bundle from the point on the boundary of the measured area.
As can be seen from the figure, in the optical system of the second example, the irradiation range of the light flux from each point in the measured region 11 coincides with the solid ellipse shown on the right side. Therefore, compared with the first embodiment, it is possible to further collect the light from the measured region and guide the light more efficiently.

As described above, in the optical system of the second embodiment shown in FIG. 2, it is possible to greatly improve the above-mentioned conditions (3) and (4) as compared with the conventional example. The light receiving efficiency of 3) is further improved as compared with the first embodiment.

[Third Embodiment] FIG. 3 shows a third embodiment of the optical system according to the present invention. It should be noted that the upper optical path diagram and the lower optical path diagram show the same optical system, and show optical paths in cross sections that include the optical axis and are perpendicular to each other. Therefore, it is omitted. In the lower left part, an enlarged view of the periphery of a hemispherical lens 32 described later is shown. In FIG. 3, the region to be measured 21, the objective lens 23, the wavelength resolving filter 25, and the sensor array 26 are the same as those in FIGS.

The apertures 22, 24 and 31 have the same functions as those in FIGS. 1 and 2, and determine the boundary of the measured region and the maximum deflection angle of the light beam passing through the objective lens.

The lens 32 is arranged slightly behind the image forming position of the measured region 21 by the objective lens 23,
It is a hemispherical lens having a diameter larger than the image of the measured region 21. The hemispherical lens 32 has a short focal length, and a light beam that obliquely enters the hemispherical lens across the optical axis immediately before the hemispherical lens can be made substantially parallel to the optical axis after the lens exits. Moreover, as shown in the enlarged view at the lower left, the light flux emitted from the hemispherical lens 32 is condensed so as to pass through a cylindrical space having a small diameter. Further, since the hemispherical lens 32 is arranged slightly behind the image forming position of the measured region 21 by the objective lens 23, the light rays emitted from the vicinity of the boundary of the measured region 21 are incident on the incident surface of the hemispherical lens 32. However, after passing through the lens, it passes around the optical axis on the incident surface of the diffusion plate 33 after exiting the lens. As a result, the light rays from the respective points in the measured region 21 are mixed appropriately, and the angles are made substantially parallel to the optical axis.

The diffusing plate 33 is arranged at a position where the light beam emitted from the hemispherical lens 32 is in a cylindrical shape, and mixes the intensities of the light beams incident on the diffusing plate 33 and the unevenness of the incident angle, and diffuses and emits them backward. However, since the diffusing plate 33 is arranged at a position other than the image forming position, the light rays from the respective points in the measured region 21 are already mixed, and the hemispherical lens 32 causes the light rays to enter. The angles are also aligned close to the optical axis. Therefore, the diffusing plate 33 has a function of compensating the mixing of light rays by the front lens system.

The lens 27 is a cylindrical lens which has a curvature in a direction perpendicular to the column direction of the sensor array but has no curvature in a parallel direction. The cylindrical lens 27 has a function of condensing a light ray spreading from the emission point of the diffusion plate 33 to the rear of the optical system in the direction having the curvature. Therefore, the cylindrical lens 27 must be arranged so that its focal position is a position (rearward) away from the position of the diffusion plate 33. The cylindrical lens 27
Is arranged so that an image at the position of the diffusion plate 33 in the measured region 21 is formed near the light receiving surface of the sensor array 26, the light receiving efficiency at the light receiving surface of the sensor array is improved.

The lens 28 is a cylindrical lens having a curvature in the direction parallel to the column direction of the sensor array 26 but no curvature in the vertical direction. The cylindrical lens 28 is arranged so that the focal point thereof coincides with the position of the diffusion plate 33 in the direction of curvature. With this arrangement,
The light beam that has passed through the cylindrical lens 28 becomes a light beam that is substantially parallel to the plane perpendicular to the column direction of the sensor array. Therefore, the light rays are obliquely incident on both ends of the filter,
The problem of the conventional optical system is solved.

In FIG. 3, the dotted line and the solid line respectively indicate the range of the light flux emitted from the center and the point on the boundary of the measured region 21, as in the first and second embodiments. In the optical system of the third example, the irradiation range of the light flux from each point in the measured region 21 coincides with the solid ellipse shown on the right side. Therefore, the light from the measured region can be condensed to the same extent as in the second embodiment, and the light can be efficiently guided.

As described above, in the optical system of the third embodiment shown in FIG. 3, the above-mentioned conditions (3) and (4) can be greatly improved as compared with the conventional example. Further, in the optical system of the third embodiment, the diffusion plate 3
It is possible to design the optical system separately before and after 3. More specifically, the optical system behind the diffusion plate 33 is not directly related to the measured region 21 determined by the front optical system. Therefore, it suffices to design in consideration of only the diffusion of the diffused light by the diffuser plate 33 and the conversion into parallel rays. With this configuration, even if some mounting error occurs, the influence on the performance of the entire optical system is small.
With respect to the installation of the above, the tolerance range of the installation error can be made large. Further, the converged light that has passed through the objective lens 23 is not converged at one point by passing through the hemispherical lens 32, but is converged into a cylindrical space having a small diameter. A large tolerance for installation error can be taken.

Although a hemispherical lens is used as the lens 32 in this embodiment, this lens is not limited to a hemispherical lens as long as it has a short focal length (for example, a spherical lens).

[Fourth Embodiment] FIG. 4 shows a fourth embodiment of the optical system of the present invention. In the fourth embodiment, the optical system of the third embodiment shown in FIG. 3 is separated into front and rear at the position of the diffusion plate 33, and the space between them is optically connected by an optical fiber bundle 53 instead of the diffusion plate. is there. Optical fiber bundle 5
The optical system in front of 3 has the same configuration as that of the third embodiment, and therefore the description thereof is omitted here.

The light rays incident on the fiber are transmitted to the emission end while undergoing multiple reflections in various directions inside the fiber, so that the light rays are emitted from the emission end in various directions. Therefore, when the fibers are used as a bundle, the light rays emitted from the individual fibers spread out and overlap each other.
From this, the optical fiber bundle 53 functions not only as a light transmitting means but also as a light mixing means. In this embodiment, the optical fiber bundle is used because the effect of mixing light is high, but the same effect can be obtained even with a single-core optical fiber or a so-called optical path rod.

The optical system behind the optical fiber bundle 53 has exactly the same construction as that of the third embodiment, like the front optical system, and therefore its explanation is omitted.

Since the optical fiber bundle can be freely bent and the length can be freely designed, unlike the optical systems of the first to third embodiments, the fourth optical fiber bundle can be used.
In the optical system of the embodiment, the rear optical system can be arranged independently of the optical axis of the front optical system. Therefore, it is possible to expand the degree of freedom in designing the colorimeter device.

As an application example of this embodiment, it is possible to apply the optical system after the optical fiber 53 to the conventional example shown in FIGS. Specifically, the incident end of the optical fiber may be arranged at the position of the light receiving surface of the sensor array 106 shown in FIG. 6 or 7. With this application, as in the fourth embodiment, the degree of freedom in designing the colorimeter device can be increased.

[Fifth Embodiment] FIG. 5 shows a fifth embodiment of the optical system according to the present invention. In the drawing, the upper optical path diagram and the lower optical path diagram show the same optical system, and show optical paths in cross sections including the optical axis and perpendicular to each other. The fifth embodiment is an embodiment in which the optical fiber 53 of the fourth embodiment shown in FIG. Therefore, illustration and description of the optical system in front of the optical fiber are omitted.

In FIG. 5, 71 indicates an optical fiber. As shown in the figure, the emission end of the optical fiber 71 has a flat ribbon shape in the column direction of the sensor array 66, the width of the emission end formed into the ribbon shape is wider than the length of the row of the sensor array, and the thickness is the sensor. Array column width or less. The lens 67 is a cylindrical lens which has a curvature in a direction perpendicular to the column direction of the sensor array but has no curvature in a parallel direction. Cylindrical lens 6
7 forms an image of the emission end surface of the optical fiber bundle 71 on the light receiving surface of the sensor array 66 in the direction of curvature. As a result, the light rays that exit the optical fiber end and that spread in the direction perpendicular to the column direction of the sensor array are collected.

Reference numeral 72 denotes a wall surface of a plurality of flat plates which is arranged between the cylindrical lens 67 and the wavelength resolving filter 65 and which is perpendicular to the ribbon-shaped plane of the optical fiber bundle 71 and also to the light receiving surface of the sensor array. A light-shielding wall is shown.
Due to the arrangement of the light shielding wall 72, the light rays incident on the spectroscopic sensor are limited to the light rays that can pass between the adjacent wall surfaces, and the maximum incident angle of the incident light can be suppressed. That is, it is possible to reduce the problem that the light rays are obliquely incident on the filter surface. The incident angle of the light beam is determined by the distance and length of the light shielding wall and the arrangement distance from the sensor array surface.

According to the optical system of the present embodiment, since the light rays which are obliquely incident on the filter surface are limited by the light shielding wall 72, the angle range shielded by the light shielding wall differs depending on the position in the column direction of the sensor array. . Therefore, the above first to fourth
The effect is slightly inferior as compared with the optical system that uses the cylindrical lens of the embodiment to make parallel light. However, since the cylindrical lens is not used, the components are inexpensive and high assembly precision is not required.
Therefore, when it is applied to a measurement system that does not require a high degree of accuracy, for example, a measurement system for monitoring the illumination light source of a colorimeter, it is advantageous in terms of component cost and assembly man-hours.

Note that this embodiment can also be applied to the conventional example shown in FIGS. 6 and 7 as in the case of the fourth embodiment.

[0060]

As described above, in the light receiving system of the colorimeter of the present invention, since the cylindrical lens 7 is provided, the light flux emitted from each point in the measured region is arranged in the array of the sensor array. The light is collected in the direction perpendicular to the direction. Therefore, it is possible to greatly improve the light receiving efficiency as compared with the conventional optical system. Further, since the cylindrical lens 8 is provided, the light to be measured becomes a light beam that is substantially parallel to the plane perpendicular to the column direction of the sensor array after passing through the cylindrical lens 8. Therefore, it is possible to reduce the problem that the light rays are obliquely incident on the wavelength resolution filter.

Further, by providing the cylindrical lens 19, it is possible to match the irradiation range of the light flux from each point in the measured region, and it is possible to further collect the measured light. Therefore, the light receiving efficiency can be further increased.

Further, by providing the short focus lens 32 and the diffusing plate 33, it is possible to evenly mix the light rays emitted from the respective points in the measured region. Moreover, by passing through the diffuser plate, the optical system behind the diffuser plate has no direct relationship with the measured region determined by the optical system in front.
Therefore, the optical system can be designed separately before and after the diffuser plate, and the assembling accuracy of the optical system can be relaxed.

Further, by providing the optical fiber 53, it is possible to increase the degree of freedom in designing the colorimeter device. Specifically, the optical fiber can be bent freely and its length can be freely adjusted. Therefore, it is possible to arrange the optical system after the optical fiber at a position irrelevant to the optical axis of the front optical system, and it is possible to freely design the device in which this optical system is mounted.

Further, the provision of the optical fiber bundle 71 having a flat ribbon-shaped emission end face and the light-shielding wall 72 composed of the wall surfaces of a plurality of flat plates causes a problem that light rays are obliquely incident on the wavelength decomposing filter. Can be reduced. By limiting the obliquely incident light rays by the light shielding wall 72, it is possible to realize an optical system that is less expensive and does not require fine assembly precision as compared with an optical element such as a cylindrical lens described above.

[Brief description of drawings]

FIG. 1 is an optical path diagram of an optical system in a first embodiment of the present invention.

FIG. 2 is an optical path diagram of an optical system according to a second embodiment of the present invention.

FIG. 3 is an optical path diagram of an optical system in a third embodiment of the present invention.

FIG. 4 is an optical path diagram of an optical system according to a fourth embodiment of the present invention.

FIG. 5 is an optical path diagram of an optical system in a fifth embodiment of the present invention.

FIG. 6 is an optical path diagram of an optical system in a conventional example of the present invention.

FIG. 7 is an optical path diagram of an optical system in another conventional example of the present invention.

[Explanation of symbols]

 2: Aperture 3: Objective lens 4: Aperture 5: Wavelength decomposition filter 6: Sensor array 7: Cylindrical lens 8: Cylindrical lens 16: Cylindrical lens 31: Aperture 32: Short focus lens 33: Diffuser 51: Aperture 52: Short focus Lens 53: Optical fiber 71: Optical fiber bundle 72: Light shielding wall

Claims (10)

[Claims] 1. A sensor array 6 for converting incident light into an electric signal, a wavelength resolution filter 5 arranged on the front surface of the sensor array, the transmission wavelength of which changes in the column direction of the sensor, and an image of an area to be measured having a predetermined size. The objective lens 3 that forms an image on the image forming plane, the boundary of the light rays emitted from the measured region and the maximum deflection angle with respect to the optical axis are arranged in at least two places near the objective lens and near the image forming plane of the objective lens. The apertures 2 and 4 to be determined, and the aperture arranged between the image plane of the region to be measured by the objective lens and the wavelength resolution filter, having a curvature in the direction perpendicular to the row of the sensor array, and having an exit pupil of the objective lens. A light receiving optical system for a colorimeter, comprising: a cylindrical lens 7 that forms an image in the vicinity of the sensor array surface only on the direction component of the light beam passing through the sensor array column. 2. The light receiving optical system of the colorimeter according to claim 1, further comprising: a lens disposed between the cylindrical lens and the wavelength resolution filter, having a curvature in a direction parallel to a row of the sensor array, and having a focal point. Is a light receiving optical system of a colorimeter, wherein the second cylindrical lens 8 is arranged in the vicinity of the image forming position of the measured region by the objective lens. 3. A sensor array 16 for converting incident light into an electric signal, a wavelength resolution filter 15 arranged on the front surface of the sensor array, the transmission wavelength of which changes in the column direction of the sensor, and an image of the measured region to a predetermined size. The objective lens 13 that forms an image on the image forming surface, and the boundary of the light rays emitted from the measured region and the maximum deflection angle with respect to the optical axis are arranged at least at two positions near the objective lens and near the image forming surface of the objective lens. Apertures 12 and 14 to be determined, and a sensor array of light rays which are arranged in the vicinity of the image plane of the region to be measured by the objective lens, have a curvature in a direction parallel to the rows of the sensor array, and pass through the exit pupil of the objective lens. For imaging only the direction component parallel to the row of
Of the cylindrical lens 19 and of the sensor array of the light rays that are arranged behind the image plane of the measurement area of the objective lens and have a curvature in the direction perpendicular to the rows of the sensor array and that pass through the exit pupil of the objective lens. A second light receiving optical system of a colorimeter, comprising: a second cylindrical lens 17 for forming an image only in the direction perpendicular to the column in the vicinity of the sensor array surface. 4. The light-receiving optical system of the colorimeter according to claim 3, further comprising a curvature arranged in a direction parallel to a row of the sensor array, which is arranged between the second cylindrical lens and the wavelength resolution filter. A third focal point arranged so that its focal point is in the vicinity of the image formation position of the measurement area of the objective lens.
2. A light receiving optical system of a colorimeter, which is equipped with the cylindrical lens 18 of FIG. 5. A sensor array 26 for converting incident light into an electric signal, a wavelength resolution filter 25 arranged in front of the sensor array and having a transmission wavelength changing in the sensor column direction, and The objective lens 23 that forms an image on the image forming plane, and the boundary of the light rays emitted from the measured region and the maximum deflection angle with respect to the optical axis are arranged at least at two positions near the objective lens and near the image forming plane of the objective lens. The apertures 22, 24, 31 to be determined, the short focus lens 32 arranged near the rear of the image formation position of the measurement area by the objective lens, and the position where the light flux behind the short focus lens converges. A diffusion plate 33, disposed between the diffusion plate and the wavelength resolution filter,
A cylindrical lens 27 that has a curvature in a direction perpendicular to a row of the sensor array, and forms only a direction component of an image of the diffuser plate perpendicular to the row of the sensor array in the vicinity of the sensor array surface. Light receiving optical system of colorimeter. 6. The light receiving optical system of the colorimeter according to claim 5, further comprising: a lens arranged between the cylindrical lens and the wavelength resolution filter, having a curvature in a direction parallel to a row of the sensor array, and having a focal point. The second light receiving optical system of the colorimeter, wherein the second cylindrical lens 28 is arranged so as to be in the vicinity of the diffusion plate. 7. A sensor array 46 for converting incident light into an electric signal, a wavelength resolution filter 45 arranged on the front surface of the sensor array and having a transmission wavelength varying in the column direction of the sensor, and The objective lens 43 that forms an image on the image forming plane, the boundary of the light rays emitted from the measured region and the maximum deflection angle with respect to the optical axis are arranged at least at two positions near the objective lens and near the image forming plane of the objective lens. Apertures 42, 44, 51 to be determined, a short focus lens 52 arranged in the vicinity of the rear of the image formation position of the measurement area by the objective lens, and an incident end face at a position where the light flux behind the short focus lens converges. The arranged optical fiber 53 is arranged between the emission end face of the optical fiber and the wavelength resolving filter, and has a curvature in a direction perpendicular to the row of the sensor array. A light receiving optical system of a colorimeter, comprising: a cylindrical lens 47 for forming only a direction component of an image of the emission end face in a direction perpendicular to a row of the sensor array in the vicinity of the sensor array surface. 8. The light receiving optical system of the colorimeter according to claim 7, which is further arranged between the cylindrical lens and the wavelength resolution filter, has a curvature in a direction parallel to a row of the sensor array, and has a focal point. Is provided in the vicinity of the emission end face of the optical fiber, and the second cylindrical lens 48 is provided in the light receiving optical system of the colorimeter. 9. A sensor array 66 for converting incident light into an electric signal, a wavelength resolution filter 65 arranged on the front surface of the sensor array for changing the transmission wavelength in the column direction of the sensor, and an image of a measured region being predetermined. The objective lens 43 that forms an image on the image forming plane, the boundary of the light rays emitted from the measured region and the maximum deflection angle with respect to the optical axis are arranged at least at two positions near the objective lens and near the image forming plane of the objective lens. Apertures 42, 44, 51 to be determined, a short focus lens 52 arranged in the vicinity of the rear of the image formation position of the measurement area by the objective lens, and an incident end face at a position where the light flux behind the short focus lens converges. The optical fiber bundle 71 is arranged so that the emission end face has a ribbon shape, and the longitudinal direction of the emission end face having the ribbon shape is parallel to the row of the sensor array. Between the shooting end face and the wavelength resolving filter, arranged vertically to the row of the sensor array,
A light-receiving optical system for a colorimeter, comprising: a plurality of light-shielding walls 72 that limit obliquely incident light to the wavelength resolution filter. 10. The light receiving optical system of the colorimeter according to claim 9, further comprising a curvature arranged in a direction perpendicular to a row of the sensor array, the light receiving optical system being disposed between the emission end face of the optical fiber bundle and the wavelength resolving filter. A light receiving optical system of a colorimeter, which is provided with a cylindrical lens 67 for forming only a direction component of an image of the emission end face of the optical fiber bundle in a direction perpendicular to the sensor array row in the vicinity of the sensor array surface.