JPH04326027A - Spectrophotometer - Google Patents

Abstract

PURPOSE:To achieve a simplification of the apparatus and higher endurance by a system which performs a spectral analysis depending on changes in the angle of incidence into an interference filter. CONSTITUTION:Light 12 to be measued consists of a luminous flux emitted from an area restricted in a one-dimensional direction with a slit 2 to be turned to a parallel luminous flux by a collimation means 4 and diffused by a beam diameter conversion means 5. An interference filter device 7 consists of an interference filter with a uniform thickness formed cylindrical with the axis thereof in parallel to the slit 2 and a intensity distribution measuring means consists of a two-dimensional intensity distribution measuring means 10 to measure a two-dimensional distribution in the direction parallel with and orthogonal to the slit 2. A polarization means 6 is provided as arranged between the collimation means 4 and the intensity distribution measuring means 10. This spectroscopic photometry of the light to be measued is performed in relation to a transmission light intensity distribution in the direction orthogonal to the slit 2 of an interference filter device 7 and an angle of incidence into the interference filter device 7 at the position corresponding thereto.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spectrophotometric device, and more particularly, to a spectrophotometric device suitable for a photometric system of a color photographic printer.

0002

2. Description of the Related Art For example, in a conventional surface exposure printer, the color density of the negative is detected by photometrically measuring the spectral distribution of the negative using a three-color separation filter whose spectral sensitivity almost matches the spectral sensitivity of photographic paper. However, this method has the drawback that it is difficult to match the three-color separation filter accurately to the spectral sensitivity of the photographic paper, and in addition, it cannot cope with deviations in the spectral sensitivity of the photographic paper. Furthermore, in order to change the exposure conditions depending on the type of negative, we currently rely on the barcode displayed on the cartridge, which can sometimes lead to mistakes.

Therefore, in order to match the color density of the negative with the spectral sensitivity of the photographic paper, a means for detecting it using a weighted measurement system is disclosed in Japanese Patent Laid-Open No. 1-134353 and Japanese Patent Laid-Open No. 1-1427.
It has been proposed in No. 19, etc. In these,
A spectroscopic prism is used as a spectroscopic system to line-scan a negative and measure the spectral density distribution of each resolved pixel in the frame area or non-image area between frames, and also uses diffraction gratings, interference filters, etc. It is said that this is possible. However, spectroscopic systems such as prisms and diffraction gratings require large devices and are questionable in terms of durability.

[0004] Furthermore, as a method using an interference filter, a method using an interference filter in which the transmission wavelength is sequentially different for each location was proposed in Japanese Patent Application Laid-Open No. 64-57134, and it was actually commercialized as a colorimeter. However, it is difficult to manufacture such interference filters whose transmission wavelengths differ from place to place.

[0005]

[Problems to be Solved by the Invention] The present invention was made in view of the above circumstances, and its purpose is to simplify the device and improve its durability by using a spectroscopic method different from the conventional method described above. It is an object of the present invention to provide a spectrophotometric device.

[0006]

[Means for Solving the Problems] The spectrophotometer of the present invention achieves the above object, in which a parallel beam of light to be measured spreads in at least a predetermined direction, and the inclination angle differs depending on the position in that direction, and mutually the same characteristics are mutually different. An interference filter device consisting of a combination of partial interference filters is disposed, and means for measuring the intensity distribution of the light beam transmitted through the interference filter device in the direction is provided, and the intensity distribution signal from the intensity distribution measuring means and the corresponding position are provided. This method is characterized in that the spectral distribution of the light to be measured is measured by associating it with the inclination angle of the partial interference filter.

In this case, as a specific example, the light to be measured is emitted from an area limited by a slit in a direction perpendicular to the predetermined direction, is converted into a parallel beam by a collimating means, and is converted into a parallel beam by a beam diameter converting means. The interference filter device consists of a light beam expanded in a predetermined direction. and a two-dimensional intensity distribution measuring means for measuring a two-dimensional distribution in a direction parallel to the slit, and at least a collimating means and a polarizing means disposed between the intensity distribution measuring means. can.

The spectrophotometric device of the present invention is suitable for a film spectrophotometric system of a color photographic printing device.

[0009]

[Operation] In the present invention, an interference filter device consisting of a combination of partial interference filters having mutually identical characteristics is disposed in a parallel beam of light to be measured that spreads in at least a predetermined direction, and the inclination angle differs depending on the position in that direction. A means for measuring the intensity distribution in the direction of the light beam transmitted through the interference filter device is provided, and by associating the intensity distribution signal from the intensity distribution measuring means with the inclination angle of the partial interference filter at the corresponding position, it is possible to measure the intensity of the light to be measured. Because it measures spectral distribution, it does not perform wavelength dispersion like prisms and diffraction gratings, making the photometry system simple and compact.Also, as an interference filter, it is possible to evaporate a filter for a specific wavelength. Generally, interference filters are easy to design and manufacture. Furthermore, since there are no moving parts, the optical axis does not change before and after spectroscopy, allowing stable spectroscopy.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the spectrophotometric device of the present invention is applied to a photometric system of a color photographic printer will be described below. Even if the interference filter has a constant film thickness, if the angle of incidence i0 is increased from zero degrees by tilting the interference filter with respect to the incident light, the interference filter will change as shown in FIGS. 6(A) and (B). It is known that the transmitted wavelength shifts to the shorter wavelength side as the incident angle i0 increases, and the transmittance of the shifted wavelength also changes. Therefore, by preparing an interference filter in which the angle of incidence i0 with respect to the incident parallel light beam differs depending on the location within the beam cross section, and measuring the measured light intensity in correspondence with the location, spectrophotometry of the incident light beam becomes possible. . The spectrophotometer of the present invention utilizes this principle.

FIG. 1 shows a side view of a spectrophotometer according to an embodiment of the present invention, and FIG. 2 shows a perspective view thereof. However, in FIG. 2, the polarizer is omitted. The apparatus includes an illumination device 3 that illuminates the negative film 1 to be measured, a slit 2 that restricts the transmitted light of the negative film 1 to only a stripe area that intersects the traveling direction of the negative film 1, and a slit 2.
collimator optical system 4 that converts the light that has passed through the
, a beam expander 5 that expands the narrow parallel beam converted by the collimator optical system 4 in the direction of travel of the negative film 1, and s in the beam from the beam expander 5.
A polarizer 6 consisting of a polarizing filter, a polarizing beam splitter, etc. that transmits only the p-component (FIG. 6(A)) or the p-component (FIG. 6(B)) and a uniform film thickness on the surface of the hollow transparent cylinder 8 It consists of a cylindrical interference filter 7 formed by depositing a filter film 9 and an area sensor 10. As shown, the cylindrical interference filter 7 has a shape that is divided into four equal parts by a plane passing through the axis of the cylindrical body, and its generatrix is oriented in a direction parallel to the slit 2. The collimator optical system 4 is composed of a microlens array or the like whose front focal point is arranged at the slit 2. In addition, the beam expander 5 is constructed by combining two negative and positive cylindrical lenses whose generatrix lines are parallel to the slit 2 in a confocal manner, for example, as shown in the figure. As shown in the perspective view of FIG.
1 are arranged regularly in a checkerboard pattern on two-dimensional coordinate axes that are perpendicular to each other, and one coordinate axis is the slit 2.
The other coordinate axis is arranged in a direction perpendicular to the slit 2, and a CCD or the like is used.

Since the spectrophotometer of the present invention is constructed in this way, the transmitted light from a specific position in the longitudinal direction of the negative film 1 to be measured, which is limited in a line shape by the slit 2, is transmitted by the collimator optical system 4. The beam expander 5 converts the beam into a parallel beam 12 which is expanded in the direction orthogonal to the slit 2 as shown in the figure, and the polarizer 6 extracts only the s component or the p component. It will be done. By the way, since the interference filter film 9 provided on the surface of the cylindrical interference filter 7 has a uniform thickness, the transmission wavelengths are the same as long as the incident angles i0 with respect to the surface are the same.
If the wavelength is different, the transmitted wavelength and the transmittance are as shown in Fig. 6(A).
Or change according to the graph in (B). Since the interference filter 7 has a cylindrical surface in the cross-sectional longitudinal direction of the sheet-like parallel light beam 12, the incident angle i0 of the sheet-like parallel light beam 12 with respect to the cylindrical interference filter 7 differs depending on the position in the cross-sectional longitudinal direction. . Therefore, after passing through the cylindrical interference filter 7, the sheet-like parallel light beam 12 has a different wavelength depending on its cross-sectional longitudinal position. In other words, the light that has passed through a specific position in the longitudinal direction of the slit 2 of the negative film 1 to be measured is expanded in a direction perpendicular to the slit 2, and is separated by the cylindrical interference filter 7 in the expanded direction. Therefore, as shown in FIG. 3, the position of the area sensor 10 in the direction orthogonal to the slit 2 becomes the spectral direction, and the signal from the light detection element 11 in that direction specifies the longitudinal direction of the slit 2 of the negative film 1 to be measured. It represents the spectral distribution of the concentration at the position. The same thing can be said about other positions in the longitudinal direction of the slit 2. Therefore, in the density distribution signal obtained from the area sensor 10, the information in the direction parallel to the slit 2 is the density of the negative film 1 to be measured in the longitudinal direction of the slit 2. Regarding the distribution, information in the direction perpendicular to the slit 2 represents the spectral distribution of the concentration at a specific position in the longitudinal direction of the slit 2. As is clear from the graphs in FIGS. 6(A) and 6(B), the peak transmittance differs depending on the incident angle i0 with respect to the cylindrical interference filter 7, so the spectral direction obtained from the area sensor 10 (slit 2 and the signal in the orthogonal direction) must be corrected to compensate for this. Similarly, in the spectral direction, the obtained signal must be corrected according to the illumination light spectral distribution. Furthermore, in the spectral direction, a collimator optical system 4,
Non-uniformity in measurement light distribution in intermediate optical systems such as the beam expander 5 must also be corrected.

By the way, in order to obtain the spectral density distribution of each two-dimensional pixel of the negative film 1 to be measured, the negative film 1 to be measured is continuously or stepwise as shown by the arrows in FIGS. The above measurements may be carried out while moving the object.

By the way, as is clear from FIG. 6, even if the angle of incidence i0 of a single interference filter with a predetermined film thickness changes in the range of 0° to 90°, the range of wavelengths that can be separated is not very wide. . In order to widen the range of spectroscopy, use two or more interference filters with different transmission wavelengths at the incident angle i0 = 0°, and perform spectrophotometry on each interference filter in the same way as above. It can be made wider. One method is to use a device like that shown in FIG.
It is sufficient to provide more than one stage and make the characteristics of the interference filter 7 of each device different. Furthermore, as shown in FIG. 4, for example, the light beam that has passed through the collimator optical system 4 or the beam expander 5 is divided into two by a half mirror HM (a polarizing beam splitter is used as the polarizer 6 in FIG. ), each branched light beam may be separately subjected to spectrophotometry using an apparatus such as that shown in FIG. In this case as well, the characteristics of the interference filters 7 of each device are made to be different. In FIG. 4, the reference numerals of the components of one device are marked with "'" to distinguish them from the components of the other device.

Next, a modification of the interference filter is shown in FIG. In this case, a polygonal prism interference filter 70 is used instead of the cylindrical interference filter 7 described above. As shown in the figure, this interference filter 70 is formed by depositing an interference filter film 90 of uniform thickness on the surface of a hollow transparent polygonal cylinder 80, and each planar interference filter 71 is formed of a polygonal cylinder. They form an equal opening angle δθ with respect to the central axis. Therefore, in the spectral direction of the area sensor 10, the light is not dispersed continuously, but as shown in the figure, the wavelengths λ1 to λ1 are discontinuous.
The light is sampled at λi and spectrally analyzed. Furthermore, since the light receiving area decreases toward one end of the polygonal prism-shaped interference filter 70, the detection signal in the spectral direction must be corrected accordingly.

Although an embodiment in which the spectrophotometric device of the present invention is applied to a photometric system of a color photographic printer has been described above, the present invention can be applied to various other fields. For example, colorimeter, simple spectrometer, laser spectrometer, etc. Further, the present invention is not limited to the configuration of the above embodiment, and various modifications are possible.

[0017]

As explained above, according to the spectrophotometer of the present invention, there is partial interference in the parallel light beam to be measured that spreads in at least a predetermined direction, the angle of inclination of which differs from position to position in that direction, and which mutually have the same characteristics. An interference filter device consisting of a combination of filters is disposed, and means for measuring the intensity distribution in the direction of the light beam transmitted through the interference filter device is provided, and partial interference at a position corresponding to the intensity distribution signal from the intensity distribution measuring device is provided. The spectral distribution of the measured light is measured by associating it with the inclination angle of the filter, so it does not cause wavelength dispersion like a prism or diffraction grating, making the photometry system simple and compact, and it can also be used as an interference filter. It is only necessary to deposit a filter for a specific wavelength, making it easy to design and manufacture an interference filter. Furthermore, since there are no moving parts, the optical axis does not change before and after spectroscopy, allowing stable spectroscopy.

[Brief explanation of drawings]

FIG. 1 is a side view showing the configuration of a spectrophotometer according to an embodiment of the present invention.

FIG. 2 is a perspective view of the device of FIG. 1;

FIG. 3 is a perspective view for explaining the configuration and operation of the area sensor of the device in FIG. 1;

FIG. 4 is a diagram showing the configuration of another embodiment.

FIG. 5 is a diagram showing the configuration of a modified example of an interference filter.

FIG. 6 is a diagram showing transmission wavelength characteristics with respect to incident angle of an interference filter.

[Explanation of symbols]

1... Negative film to be measured 2...Slit 3...Lighting device 4...Collimator optical system 5...Beam Expander 6...Polarizer 7...Cylindrical surface interference filter 8...Hollow transparent cylindrical body 9...Interference filter membrane 10...Area sensor 11...Photodetection element 12...Sheet-like parallel light flux

Claims (3)

[Claims] 1. An interference filter device consisting of a combination of partial interference filters having different inclination angles for each position in that direction and having mutually identical characteristics is arranged in a parallel light beam to be measured that spreads in at least a predetermined direction, and the interference filter Means for measuring the intensity distribution in the direction of the light beam transmitted through the device is provided, and the spectral distribution of the light to be measured is determined by associating the intensity distribution signal from the intensity distribution measuring means with the inclination angle of the partial interference filter at the corresponding position. A spectrophotometric device characterized by measuring. 2. Light to be measured is emitted from a region limited by a slit in a direction perpendicular to the predetermined direction, is converted into a parallel beam by a collimator, and is expanded in the predetermined direction by a beam diameter converter. Become,
The interference filter device comprises an interference filter having a uniform film thickness and formed in a cylindrical or polygonal column shape with an axis parallel to the slit, and the intensity distribution measuring means is arranged in two directions, one in the predetermined direction and the other in a direction parallel to the slit. 2. The spectrophotometer according to claim 1, comprising two-dimensional intensity distribution measuring means for measuring dimensional distribution, and comprising at least collimating means and polarizing means disposed between said intensity distribution measuring means. 3. The spectrophotometric device according to claim 1, wherein the spectrophotometric device is used in a film spectrophotometric system of a color photographic printer.