JPH0850057A - Optical device for measuring two-dimensional spectral distribution - Google Patents

Abstract

PURPOSE:To make it possible to pick up the image of an object for every wavelength two-dimensionally by transmitting the image of the object, which is formed by a taking lens in parallel, and dispersing the image of the object as the parallel light with a diffraction grating, which can be vibrated. CONSTITUTION:The image of an object 1 is formed on a primary imaging plane 5 with a taking lens 3. The image of the object on the primary imaging plane 5 is transmitted to a primary' imaging plane specified on the right-side surface of the a plate 7 through the bundle of many optical fibers of the fiber optic plate 7. When the image passes the plate 7, the directivity, which is added with the lens 3, is dissolved, and the image becomes as if the optical image emerging from a perfect diffusing plane. The image of the object is sent into a transmitting-type diffraction grating 11 for every pixel with a microlens array 9. The image of the object whose direction of the ray is changed for every wavelength, which is transmitted through the diffraction grating 11, is sent into rectangular prisms 13 and 15 and divided in two dimensions. The images are not mixed with an optical images emitted from other pixels. Only the light in the specified direction of the light emitted from a certain point is picked up and cast on a screen 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device for two-dimensionally measuring the wavelength distribution of a light ray (radiation) emitted from an object (subject).

[0002]

2. Description of the Related Art Conventionally, various optical devices have been known as a system for two-dimensionally measuring spectral energy of radiation emitted from a subject for each wavelength by using a sensor, that is, as an optical device for measuring subject brightness for each wavelength. ing.

For example, there is a system using an optical bandpass filter as shown in FIG. In FIG. 5, 41
Is a subject, 43 is an optical band pass filter (band filter) that transmits only a specific band, 45 is a photographing lens,
An imager 47 measures the brightness.

In FIG. 5, a certain subject (target)
In order to measure a subject image of a specific wavelength emitted from 41, a specific narrow band optical having a width of, for example, about 5 nanometers is provided in front of an imager (normal camera, point sensor or area sensor, etc.) 47. A bandpass filter (for example, a color filter) 43 is arranged and the subject 41
Measure the brightness of.

By successively replacing the band pass filters 43 having different transmission bands and measuring the luminance of the subject 41 in each wavelength range, the object of measuring the subject image for each wavelength can be achieved.

Another conventional technique shown in FIG. 6 is a system utilizing the spectral action of diffracted light, and is used in a measuring instrument for measuring color temperature such as a pattern box. In FIG. 6, 41 is a subject, 51 is a photographing lens, 53 is a pinhole mask that blocks excess light, 55 is a lens, and 57 is a diffraction grating that slightly vibrates or rotates around its center as shown by the arrow. , 59 are lenses, and 47 is a point sensor.

In this system, a light ray (radiation) emitted from the subject 41 is focused or condensed by the photographing lens 51, passes through the pinhole mask 53, is made into substantially parallel light by the lens 55, and is incident on the reflection type diffraction grating 57. . Diffraction grating 5
The light is reflected by 7 to be separated into a spectrum, collected by a lens 59, and incident on the point sensor 47.

The diffracted light generated through the diffraction grating 57 produces interference fringes such as 0th-order light, + 1st-order light and -1st-order light.
Each of the 0th, + 1st or −1st order diffracted light is spectrally divided according to the wavelength. When the diffraction grating 57 is slightly vibrated or rotated around its center, the point sensor 47 is scanned to selectively sense an incident subject image of a specific wavelength.

[0009]

By the way, in the conventional technique using the bandpass filter 43 shown in FIG. 5, a large number of filters 43 must be prepared and the filters 43 must be replaced for each wavelength to be measured. For this reason, it is very time-consuming, time-consuming, and inconvenient.

The prior art using the diffraction grating 57 shown in FIG. 6 uses a pinhole mask 53 and a point sensor 47.
Therefore, only a certain point of the subject 41 can be measured, and this cannot be used two-dimensionally.

The present invention has been made in consideration of such a point, and an object image (or object brightness) for each wavelength is set to two.
It is intended to propose an optical device capable of three-dimensionally imaging (or measuring).

[0012]

A two-dimensional spectral distribution measuring optical apparatus according to the present invention includes a photographing lens 3 for condensing and forming a light beam emitted from a subject 1 as shown in FIG. 1 or 2, for example. , A fiber optic plate FOP7 for transmitting the formed subject image in parallel, a microlens array MLA9 for converting the transmitted subject image into parallel light for each pixel, and for splitting the parallel subject light It includes a vibrating diffraction grating 11 and at least one critical angle prisms 13 and 15 for selecting the horizontal and vertical components of a spectrally separated subject image.

The two-dimensional spectral distribution measuring optical device according to the present invention is further characterized by vibrating the diffraction grating 11 to obtain a subject image of a specific wavelength, as shown in FIG. 1 or 2, for example.

The two-dimensional spectral distribution measuring optical device according to the present invention is further provided with an area sensor 17 behind the critical angle prisms 13 and 15 to vibrate the diffraction grating 11, as shown in FIG. 1 or 2, for example. Thus, the brightness of the subject image for each wavelength can be measured by time division.

[0015]

According to the structure of the two-dimensional spectral distribution optical device of the present invention, the light rays at each point are condensed by the photographing lens 3 and transmitted in parallel by the fiber optic plate 7 to form a subject image having the same directivity. Then, the microlens array 9 collimates the light. Such a subject image is spectrally separated by the diffraction grating 11, and only the subject image of a specific wavelength out of the spectrally separated subject image is passed through the critical angle prisms 13 and 15 and a specific wavelength that is not affected by light rays at other points. The subject image of can be obtained.

Further, by vibrating the diffraction grating 11, object images in different wavelength ranges can be selected.

Further, by providing the area sensor 17 after the critical angle prisms 13 and 15, the subject image can be measured in a time division manner.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS.

FIG. 1 is a perspective view of a two-dimensional spectral distribution measuring optical device for picking up a subject image for each wavelength according to the present invention, and FIG. 2 is a plan view of this optical device. 1 and 2 is a two-dimensional spectral distribution measurement optical system,
It is also called a two-dimensional spectrophotometer or a two-dimensional spectrophotometer.

In FIGS. 1 and 2, 1 is an object, 3 is an imaging lens for forming an optical image of the object 1, 5 is a primary image forming surface on which the object image is formed, and 7 is a primary image forming surface. Fiber Optic Plate (FO) that transmits the optical image of the subject on
P).

The fiber optic plate 7 used here is an optical device in which several micron optical fibers are bundled, transmits an optical image without distortion, and has a characteristic that light quantity loss is small and bright. More specifically, the fiber optic plate 7 has a multi-fiber structure in which single fibers of several microns are bundled, and each single fiber has a core glass that transmits light, a clad glass that covers the core glass, and a core glass. It is composed of three types of absorber (EMA) glass that absorbs light leaked from the glass.

In a single fiber, total reflection occurs at the boundary due to the difference in refractive index between the core glass and the clad glass,
Transmit light.

That is, among the rays in the single fiber, the rays incident on the cladding glass at an angle larger than the maximum acceptance angle do not cause total reflection and escape to the outside of the fiber, but are absorbed by the absorber glass and Does not reach single fiber. Therefore, parallel transmission of the optical image in the fiber direction is possible without impairing the resolution. Here, with respect to the fiber optic plate 7, the surface opposite to the primary imaging surface 5 is defined as a 1 ′ primary imaging surface 8. Therefore, as shown in FIG. 3A, the optical image of the subject 1 appearing on the 1'-order image plane 8 of the fiber optic plate 7 has the same directivity.

With reference to FIGS. 1 and 2, reference numeral 9 is a microlens array (MLA) for converting a subject image appearing on the fiber optic plate 7 into a substantially parallel subject image.

Microlens array 9 used here
For this, a microlens array in which minute lenses are arranged with high precision at a pitch of about 10 microns for each point (pixel) is used. For example, “SELFOC lens” (registered trademark), which is a flat plate microlens commercially available from Nippon Sheet Glass Co., Ltd., can be used. A SELFOC lens is a kind of gradient index lens made by ion exchange technology and photolithography technology, and a minute hexagonal or hemispherical refractive index distribution region is two-dimensionally formed inside a glass substrate. It is a lens.

Referring to FIGS. 1 and 2, reference numeral 11 denotes a diffraction grating that vibrates or rotates as shown by an arrow, and the diffraction grating used here may be a transmission type or a reflection type. The diffraction grating 11 is an optical element formed by engraving a large number of grooves on a flat surface or a convex surface and obtaining a spectrum from each groove by mutual interference of diffracted light.

Reference numeral 13 is a first right-angle prism, and 15 is a second right-angle prism arranged in a positional relationship orthogonal to the first right-angle prism 13.
The right-angle prism 17 is a screen for finally displaying a subject image, for example, an area sensor or the like is arranged.

In the optical device shown in FIGS. 1 and 2, the image of the subject 1 is formed on the primary image forming surface 5 by the taking lens 3. The primary image plane 5 is defined on the left side surface of the fiber optic plate 7 which will be described later with reference to FIG. 1
The subject image on the next image forming surface 5 is transmitted to the 1'primary image forming surface 8 defined on the right side surface of the fiber optic plate through the bundle of many optical fibers of the fiber optic plate 7. . When passing through the fiber optic plate 7, the directionality added by the taking lens 1 is canceled and it becomes as if it were an optical image emerging from the perfect diffusing surface (Fig. 3).
a).

Next, the subject image on the 1'th order image plane 8 is collimated by the microlens array 9 pixel by pixel, that is, point by point and sent to the transmission type diffraction grating 11. However, the image of the subject, which has been transmitted through the diffraction grating 11 and in which the direction of the light ray has changed for each wavelength, is displayed on the screen 17 as it is.
When the light rays are incident on, the light rays in various directions are mixed, so that the light rays are mixed with the light rays of other pixels.

Therefore, the first right angle prism which is the critical angle prism (for example, only the horizontal direction of the light ray is selected).
13 and a second right-angle prism (also selecting only the vertical direction of the rays), which is also a critical angle prism and arranged orthogonally thereto, are sent to the two-dimensional distribution, and thus other two Only the light emitted from a certain point in a predetermined direction is picked up and incident on the screen 17 without being mixed with the light image emitted from the pixel.

In this optical device, since the direction of the light beam is changed for each wavelength by the diffraction grating 11, the diffraction grating 1
1 is fixed, right-angle prisms 13 and 15 and screen 1
By moving 7 in the spectral direction of the spectrum, the subject brightness for each wavelength can be measured.

However, in general, right angle prisms 13 and 15
Also, by fixing the screen 17 and oscillating or slightly rotating the diffraction grating 11 around its center, it is possible to similarly measure the subject brightness of a specific wavelength, which is a simpler configuration. By slightly vibrating the diffraction grating 11 in this manner, object images of different specific wavelengths are sequentially obtained in a time division manner.

The diffraction grating 11 may be a reflection type diffraction grating 11 'as shown in FIG. 3 (b). Spectral distributions (spectra) A and B are obtained by the mutual interference of the diffracted lights reflected by the diffraction grating 11 ', and thereafter, as in the embodiment of FIGS. 1 and 2, the orthogonal prisms 1 arranged orthogonally to each other.
Unwanted rays are removed through 3, 15.

In another embodiment shown in FIG. 4 described next, 1 is a subject, 3 is an imaging lens, 7 is a fiber optic plate (FOP), and 9 is a microlens array (MLA) such as SELFOC. , 18 is a first right-angle prism, 19 is a second right-angle prism, 11 is a reflective diffraction grating, 21 is a third right-angle prism, and 17 is a screen (or area sensor).

The embodiment shown in FIG. 4 is used when the degree of parallelism of the output light from the microlens array 9 is relatively poor. Compared to the embodiment of FIGS. 1 and 2, one more right-angle prism is provided because the first right-angle prism 1 arranged in a positional relationship orthogonal to each other.
8 and the second right-angled prism 19, the first right-angled prism 18 of the output light from the microlens array 9 is used.
Then, for example, only the output light in the horizontal direction is selected from the output light, and then, in the second right-angle prism 19, for example, only the output light in the vertical direction is selected from the output light, so that the output light from the microlens array 9 is selected. The parallelism is improved and unnecessary rays of the rays incident on the diffraction grating 11 provided in the subsequent stage are removed.

An image of the subject 1 is formed on the primary image forming surface 5 by the taking lens 3. The primary image plane 5 is defined on the left side surface of the fiber optic plate 7 which will be described later with reference to FIG. The subject image on the primary imaging plane 5 is passed through a bundle of many optical fibers of the fiber optic plate 7,
It is transmitted to the 1'-order imaging plane 8 defined on the right side surface of the fiber optic plate. When passing through the fiber optic plate 7, the directionality added by the taking lens 1 is eliminated (FIG. 3a).

Next, the subject image on the 1'th order image plane 8 is made into parallel light by the microlens array 9 pixel by pixel, that is, point by point. As described above, the parallelism of the subject image output from the microlens array 9 is improved through the first right-angle prism 18 and the second right-angle prism 19 arranged in mutually orthogonal positional relations. It is incident on the diffraction grating 11.

The subject image in which the direction of the light ray is changed by the wavelength after passing through the diffraction grating 11 is the third prism which is a critical angle prism.
The output light which is incident on the right-angled prism 21 and is totally reflected from the right-angled prism 21 is incident on the screen 17.

In this optical device, since the direction of the light beam is changed for each wavelength by the diffraction grating 11, the diffraction grating 1
1 is fixed, and the third rectangular prism 21 and the screen 1
It is also possible to measure the subject brightness for each wavelength by moving 7 in the spectral direction of the spectrum.

However, like the embodiment of FIGS. 1 and 2, generally, the third right angle prism 21 and screen 17 are fixed, and the diffraction grating 11 is oscillated or slightly rotated about its center. Similarly, a subject image of a specific wavelength can be measured, and this configuration is simpler. By slightly vibrating the diffraction grating 11 in this manner, object images of different specific wavelengths are sequentially obtained in a time division manner.

According to the optical device of the present invention, since the diffraction grating 11 can be vibrated in an extremely short time, the two-dimensional spectral distribution is measured in a short time, that is, it is observed at a certain wavelength. You can shoot a subject image. For example, when the visible light region (400 to 700 nm) is dispersed and the entire spectrum is divided into images at intervals of about 10 nm, the image is taken in a short time in the case of the NTSC system (standard system of color television), specifically, (700 nm-400 nm) / 10 nm = 30
With a frame / second, it is possible to capture the entire visible light range.

The above-mentioned embodiment is an example of the present invention.
It goes without saying that various other configurations can be adopted without departing from the scope of the present invention.

[0043]

According to the optical device of the present invention, a two-dimensional spectral distribution can be measured in a short time with an optical device having a simple structure.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a two-dimensional spectral distribution optical device according to the present invention.

2 is a plan view of the embodiment shown in FIG. 1 of the present invention. FIG.

FIG. 3A is a diagram for explaining the action of a fiber optic plate (FOP), and FIG.
It is a figure explaining the case where a reflection type diffraction grating is used in the Example of FIG. 1 or FIG.

FIG. 4 is a configuration diagram showing another embodiment of the two-dimensional spectral distribution optical device according to the present invention.

FIG. 5 is a diagram showing a conventional technique using a bandpass filter.

FIG. 6 is a diagram showing a conventional technique using a diffraction grating and a point sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Subject 3 Photographic lens 5 Primary imaging plane 7 Fiber optic plate (FOP) 8 1'primary imaging plane 9 Microlens array 11 Transmission type diffraction grating 11 ', 57 Reflection type diffraction grating 13, 15, 18, 19 , 21 Right-angle prism 17 Screen 43 Optical bandpass filter 47 Imager

Claims (3)

[Claims] 1. A photographing lens for collecting and forming an image of a light beam emitted from a subject, a fiber optic plate for transmitting the formed image of the subject in parallel, and the transmitted image of the subject for each pixel. A micro-lens array for collimating parallel light, an oscillating diffraction grating for splitting the parallelized subject image, and at least one critical angle prism for selecting horizontal and vertical components of the split subject image A two-dimensional spectral distribution measurement optical device including the. 2. The two-dimensional spectral distribution measurement optical device according to claim 1, wherein the diffraction grating is vibrated to obtain a subject image of a specific wavelength. 3. The two-dimensional spectroscopy according to claim 1, wherein an area sensor is further provided after the critical angle prism, and the diffraction grating is vibrated to measure the brightness of the subject image for each wavelength in a time division manner. Distribution measuring optics.