JPH04326028A - Spectrophotometer - Google Patents

Abstract

PURPOSE:To achieve a simplification of the apparatus and a higher endurance by a system which performs a spectral analysis depending on a change in angle of incidence into an interference filter. CONSTITUTION:Light 12 to be measured consists of a luminous flux which is emitted from an area restricted in a one-dimensional direction with a slit 2 to be turned to a parallel flux with a collimation means 4 and diffused by a beam diameter converting means 5 and a complex interference filter device 7 is provided with interference filters which is difference in angle of inclination with almost the same characteristic on respective bottom surfaces of a plurality transparent wedge members. The transparent wedge members are arranged to guide filter transmission lights independently and have two-dimensional intensity distribution measuring means 8 to measure a two-dimensional distribution in the direction parallel with and orthogonal to the slit 2. Thus, a spectroscopic photometry of the light to be measued is accomplished in relation to an intensity distribution of the transmission light analyzed spectrally in the direction orthogonal to the slit 2 with the complex interference filter device 7 and an angle of incidence into the complex interference filter 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] A spectrophotometric device of the present invention that achieves the above object has a parallel beam to be measured that spreads in at least a predetermined direction, and has substantially the same characteristics that differ from position to position in that direction. Intensity distribution measuring means for arranging a plurality of interference filters, providing guide means for guiding the light transmitted through each interference filter to different positions in the direction, and measuring the intensity distribution of the light in the direction guided by the guide means. The present invention is characterized in that the spectral distribution of the light to be measured is measured by associating the intensity distribution signal from the intensity distribution measuring means with the inclination angle of the interference filter at the corresponding position.

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. Each of the plurality of interference filters is provided on the bottom surface of a transparent wedge member disposed parallel to the slit, and the guide means is configured to sandwich a vertical angle of the transparent wedge member. The intensity distribution measuring means includes a two-dimensional intensity distribution measuring means for measuring a two-dimensional distribution in the predetermined direction and a direction parallel to the slit, and at least the collimating means and the intensity and polarizing means disposed between the distribution measuring means.

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

Note that the present invention provides interference filters having substantially the same characteristics on each bottom surface of a plurality of transparent wedge members, and
A reflective film is provided on at least two surfaces of each transparent wedge member that sandwich the apex angle, the apex of each transparent wedge member is made common, the surfaces that sandwich the apex angle are adhered to each other, and the apex side of the adhesive body is cut off with a flat surface. The present invention also includes a composite interference filter device for spectrophotometry, which is characterized in that its cut surface is used as an output surface.

0010

[Operation] In the present invention, a plurality of interference filters are arranged in a parallel beam of light to be measured that spreads in at least a predetermined direction, and each interference filter has a different inclination angle depending on the position and has almost the same characteristics. a guide means for guiding the light to different positions in the directions, and an intensity distribution measuring means for measuring the intensity distribution of the light in the directions guided by the guide means, and an intensity distribution signal from the intensity distribution measuring means. Since the spectral distribution of the measured light is measured by correlating the inclination angle of the interference filter at the corresponding position, the photometry system is simple and compact because it does not perform wavelength dispersion like a prism or diffraction grating. Also,
As the interference filter, one for a specific wavelength may be deposited on a flat surface, making it easy to design and manufacture the interference filter. Furthermore, since there are no moving parts, the optical axis does not change before and after spectroscopy, allowing stable spectroscopy. Furthermore, compared to interference filters provided on polygonal prisms or cylindrical surfaces, there is no crosstalk of transmitted light, and no measures are required to avoid it.

[0011]

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. 4(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, a plurality of interference filters with the same characteristics but different incident angles i0 are prepared depending on the location within the parallel beam cross section to be measured.
By measuring the intensity of the light to be measured that has passed through each filter, 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. The device 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 light beam that passes through the slit 2. a collimator optical system 4 that converts the light into a parallel beam; a beam expander 5 that expands the thin parallel beam converted by the collimator optical system 4 in the direction of travel of the negative film 1;
The s component in the luminous flux from the beam expander 5 (Fig. 4 (
A)) or a polarizer 6 consisting of a polarizing filter, a polarizing beam splitter, etc. that transmits only the p component (FIG. 4(B));
It consists of a composite interference filter device 7 whose configuration is shown in FIG. 2 and an area sensor 8 attached to its output surface.

As shown in FIG. 2(a), the composite interference filter device 7 includes a wedge member 9 made of a transparent material having a predetermined acute apex angle, and an interference filter film of a predetermined thickness on the bottom surface of the wedge member 9. 10, and a reflective film 11 such as an aluminum film is deposited on at least two surfaces sandwiching the apex angle, preferably also on both sides to form a unit wedge member 9, and a plurality of wedge members 9 having the same configuration are formed. Prepare (however,
Vertical angles do not necessarily have to be the same. ), as shown in Figure 2(b), the surfaces that sandwich the apex angle are glued together with their vertices (vertices) in common, and the apex side is cut off from the plane indicated by the dotted line in Figure 2(b). It is manufactured by polishing the cut surface, and this cut surface becomes the emission surface. Therefore, the light transmitted through the interference filter film 10 on the bottom surface of each unit wedge member 9 is reflected and guided between the reflective films 11 provided on the surfaces sandwiching the apex angle, and is emitted from the cut surface thereof. Therefore, the light beam that enters the composite interference filter device 7 from the interference filter film 10 side is divided according to the light receiving area of the bottom surface of each unit wedge member 9 for the incident light beam, and is internally reflected within each unit wedge member 9 and guided. The divided lights are emitted to different positions on the exit surface of the composite interference filter device 7. The area sensor 8 is composed of a CCD or the like in which minute photodetecting elements are regularly arranged in a checkerboard pattern in two orthogonal coordinate directions, and as shown in FIG. 2(c), one of the coordinates is The light-receiving surface side is bonded to the output surface of the composite interference filter device 7 so that the direction is parallel to the top side of the composite interference filter device 7. In addition, in FIG. 1, the surfaces that sandwich the apex angle of each unit wedge member of the composite interference filter device 7 are located parallel to the slit 2. In addition, the collimator optical system 4
The beam expander 5 consists of a microlens array, etc. whose front focal point is arranged at the slit 2, and the beam expander 5 confocally connects two cylindrical lenses, one negative and one positive, whose generating lines are parallel to the slit 2, as shown in the figure. It is constructed by combining them.

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 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 films 10 provided on the bottom surface of each unit wedge member 9 of the composite interference filter device 7 have a uniform predetermined film thickness, the transmitted wavelengths are the same as long as the incident angles i0 with respect to the surfaces thereof are the same. However, if the composite interference filter device 7 is configured as described above, the incident angles i0 of the sheet-like parallel light beams 12 on the interference filter film 10 of each unit wedge member 9 will be different from each other, and their transmission wavelength and transmittance will be different. differs according to the graph of FIG. 4(A) or (B). Therefore, the sheet-like parallel light beam 12 that enters the composite interference filter device 7 from the interference filter film 10 side is divided according to the light-receiving area of the bottom surface of each unit wedge member 9 for the incident light beam. Only the light having the wavelength corresponding to the incident angle i0 is selected and guided by internal reflection within each unit wedge member 9, reaching different positions on the output surface of the composite interference filter device 7, and the light reaching different positions. The intensity is detected by area sensor 8. That is, 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 then separated into spectra in the expanded direction by the composite interference filter device 7. Therefore, the position of the area sensor 8 in the direction perpendicular to the slit 2 becomes the spectral direction, and the signal from the photodetection element in that direction represents the spectral distribution of the density at a specific position in the longitudinal direction of the slit 2 of the negative film 1 to be measured. It turns out. 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 8, 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. Note that even if the incident light has a uniform spectral distribution, the amount of light reaching the area sensor 8 will be affected by differences in light receiving area, difference in guide rate, and difference in transmittance due to the inclination angle of the interference filter (Figure 4 (A)
and (B)) etc.), the detection signal from the area sensor 8 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, it is also necessary to correct non-uniformity in measurement light distribution of intermediate optical systems such as the collimator optical system 4 and the beam expander 5.

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 moved continuously or stepwise as indicated by the arrow in FIG. The above measurements may be performed while the

By the way, as is clear from FIG. 4, even if the incident angle i0 of a single interference filter with a predetermined film thickness changes in the range of 0° to 90°, the wavelength range that can be spectrally dispersed 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. 3, 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. Also in this case, the characteristics of the interference filter film 10 of the composite interference filter device 7 of each device are made to be different. In FIG. 3, the reference numerals of the components of one device are marked with "'" to distinguish them from the components of the other device.

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.

[0018]

As explained above, according to the spectrophotometer of the present invention, in the parallel light beam to be measured which spreads in at least a predetermined direction, there are a plurality of parallel light beams having substantially the same characteristics that differ from position to position in that direction. Place the interference filter of
A guide means for guiding the light transmitted through each interference filter to different positions in each of the directions is provided, and an intensity distribution measuring means is provided for measuring the light intensity distribution in the direction guided by the guide means, The spectral distribution of the measured light is measured by associating the intensity distribution signal with the inclination angle of the interference filter at the corresponding position.
Because it does not cause wavelength dispersion like prisms and diffraction gratings,
The photometry system becomes simple and compact, and the interference filter can be easily designed and manufactured because it is sufficient to deposit a filter for a specific wavelength on a flat surface. Furthermore, since there are no moving parts, the optical axis does not change before and after spectroscopy, allowing stable spectroscopy. Furthermore, compared to interference filters provided on polygonal prisms or cylindrical surfaces, there is no crosstalk of transmitted light, and no measures are required to avoid it.

[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 diagram for explaining the configuration of a composite interference filter device.

FIG. 3 is a diagram showing the configuration of another embodiment.

FIG. 4 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…Composite interference filter device 8...Area sensor 9... Wedge member 10...Interference filter membrane 11...Reflection film 12...Sheet-like parallel light flux

Claims (4)

[Claims] [Claim 1] A plurality of interference filters having substantially the same characteristics and having different inclination angles depending on the position in that direction are arranged in a parallel beam to be measured that spreads in at least a predetermined direction, and the light transmitted through each interference filter is A guide means for guiding the light to different positions in each of the directions is provided, and an intensity distribution measuring means is provided for measuring a light intensity distribution in the direction guided by the guide means, and a position corresponding to an intensity distribution signal from the intensity distribution measuring means is provided. 1. A spectrophotometric device that measures the spectral distribution of light to be measured by associating it with the inclination angle of an interference filter. 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,
Each of the plurality of interference filters is provided on the bottom surface of a transparent wedge member arranged parallel to the slit, and the guide means is composed of a reflective film provided on two surfaces sandwiching an apex angle of the transparent wedge member, Further, the intensity distribution measuring means includes a two-dimensional intensity distribution measuring means for measuring a two-dimensional distribution in the predetermined direction and a direction parallel to the slit, and the polarized light is disposed between at least the collimating means and the intensity distribution measuring means. 2. The spectrophotometric device according to claim 1, further comprising 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. 4. An interference filter having substantially the same characteristics is provided on each bottom surface of the plurality of transparent wedge members, and a reflective film is provided on at least two surfaces of each transparent wedge member sandwiching the apex angle,
A composite interference filter for spectrophotometry, characterized in that the apex of each transparent wedge member is made common, the surfaces sandwiching the apex angle are glued together, the apex side of the adhesive body is cut off with a flat surface, and the cut surface is used as the output surface. Device.