CS224765B1 - Test patterns for measurement of frequency characteristics of photochemical sensitive materials - Google Patents

Description

The invention relates to test patterns for measuring the frequency properties of photochemically sensitive photographic and reprographic images.

Frequency properties of these materials, i.e. properties related to sharpness, resolution, etc., are often characterized by modulation transfer functions or by functions and quantities related to modulation transfer functions. Typically, a set of signal records with suitably graded spatial frequencies is produced on the test material, the records are processed into a visible image by a chemical process, and the optical density or other quantities characterizing light absorption in simple parts of the image are measured. These data shall be converted into effect exposure values using the material characteristics; the values of the modulation factor are then determined from these and from the quantities defining the measurement signal.

Rectangular and quasi-harmonic signals obtained from test patterns are often used for these measurements. They usually contain a set of sub-patterns, which are sources of measuring signals with a certain spatial frequency, rectangular and quasi-harmonic signals can be created from so-called intensity patterns, ie patterns in which the length dependence of transmittance (or reflection) corresponds to the desired signal . The progression of the transmittance factor is decisive for patterns in a transparent embodiment, the progression of the reflection coefficient for patterns in the reflective embodiment. In addition, so-called surface patterns are used for generating quasi-harmonic signals.

To determine the modulation transfer function by conventional methods, two groups of data are required: quantities obtained by measurement on test pattern images and quantities required to determine the characteristics of the test material. The second set of data is usually determined from specific measurement structures, in particular from sensitograms.

The necessary characteristics of the characteristic curve can be obtained without sensitiograms by evaluating the set of test pattern records for measuring frequency properties; the records differ from each other by the total exposure.

When using the previously known test patterns, it is necessary to gradually record the test material with different exposure. Passing distance between the individual records places demands on the stability and reproducibility of the exposure and on the accuracy of its adjustment. The spatial distance between the individual records on the test material increases the demands on the uniformity of the chemical processing of the records as well as on the uniformity of the properties of the tested material.

These drawbacks eliminate test patterns for measuring the frequency properties of photochemically sensitive materials according to the invention, comprising one or more sub-patterns for generating measurement signals each having certain spatial frequencies, the essence of which is that at least one of the sub-patterns consists of two or more parts that differ from each other by the mean value of the reflection or transmission factor ·

The desired graduation of the mean reflection or transmission coefficient on the individual parts can be achieved, for example, by covering the parts of the sub-patterns with optical filters (layers of the light-absorbing substance) of different optical density.

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Likewise, it is possible to influence said mean values by coloring the substrate of the individual parts by staining or photochemically excluded silver. By increasing the concentration of dye or silver, the transmittance or reflectivity is reduced. In contrast to the previous procedure, there are also changes in the modulation factor, which must be respected when selecting the transmittance or reflectance factor of the other parts of the sub-patterns.

For flat-type test patterns consisting of columnar groups of absorbing pads, the mean values of the transmittance or reflection coefficient may also be effectively influenced by including parallel-absorbing pads in the columns forming the different sub-patterns so that their overall lengths (measured in • direction of the columns) in individual sub-patterns differed.

From the light absorption differences in the images of these sub-pattern groups and the relationship between the mean values of the transmittance (reflection) of these sub-pattern groups, the performance characteristics of the test material needed to convert the quantities characterizing the material response to the measurement signal to effect exposures are determined .

The advantage of the invention is that it is not necessary to use separate measurement structures to determine the characteristics compared to conventional procedures, and that using a procedure based on evaluation of a set of test pattern records different in total exposure produces the necessary records rather than sequential shooting at different exposure levels (as for known test patterns), but at the same time, a single exposure. This primarily separates the overall exposure control process from the actual shooting and moves into the pattern creation process; at this stage, the relationships between sub-exposures can be determined accurately and once and for all. Using the patterns according to the invention, either the same accuracy of measurement of the frequency properties of the test materials is achieved with lower demands on stability and accuracy of exposure and uniformity of chemical processing, or higher accuracy

224,765 with the same characteristics of the procedures used to record and process records. The practical consequence of the new test pattern solution is to reduce the number of records that need to be captured, measured and evaluated to obtain sufficiently accurate test material data, resulting in reduced labor and time savings.

Two exemplary embodiments of the test patterns of the invention are shown in the accompanying drawings. In both cases, sheet metal-type test pieces consisting of columns of absorbing pads are shown.

In Fig. 1, the sub-pattern is based on two identical groups (columns) of the shaped faces 1 and 2. Group 2 is covered by an optical filter 3 (eg absorbing foil or glass filter), an even increase in absorption in the covered portion reduces the mean transmittance reflection) and hence the mean exposure value in the image of this part. Similarly, without the use of a filter, the pattern substrate can be colored with dye or photochemically excluded silver. Both procedures are suitable for both intensity and flat test patterns.

In Fig. 2, the sub-figures form two column groups of absorbent pads 4 and 5. Group 4 is formed by shaped absorbent pads. The group 5 also includes rectangular absorbing pads 6, which do not change the signal shape, but reduce the mean value of the transmittance (or reflection) of group 5 compared to group 4. In principle, the same technological process can be used to create shape and straight especially photochemical.

The invention can be used not only for microsensitometric measurement of photographic and reprographic materials, but also for measurement of frequency properties of other materials and systems for recording image information. The advantages of the test patterns according to the invention can also be applied to systems which respond to irradiation even by changing the distribution of electric charge, the formation of spatial relief and the like.

Claims (4)

Object of the invention 224 765 Test patterns for measuring the frequency properties of photochemically sensitive materials containing one or more sub-patterns for generating measurement signals of a certain spatial frequency, characterized in that at least one of the sub-patterns consists of two or more portions differing from each other by the mean reflection factor or penetration. 2. Test patterns according to claim 1, characterized in that at least one part of the partial pattern is covered by an optical filter. 3. Test patterns according to claim 1, characterized in that the substrate of at least one part of the partial pattern is colored with photochemically excluded silver or dye. 4. Test patterns according to claim 1, comprising columnar groups of absorbing pads, wherein at least one column comprises columnar-shaped, parallel-dimensional absorbing pads, characterized in that the total lengths of the parallelogram absorbing pads (6) are in at least two columns (4, 5). ) in different parts of the sub-pattern different from each other.