DE1069901B - - Google Patents

Description

Federal Republic of Germany

GERMAN

PATENT OFFICE

PATENT LETTER 1069 ANMEtDKTA C:

BKEANITTMACHnNG
DERANMBLDUNe
AND AU86ABE THE
AUSLKCSSCHHim

ADSGAHB THE
PATENT LETTERING:

kl. 42 h 34/08

IHTEBNAT.ZL. GOlj 6 SEPTEMBER 1 »S7

November 26th, 1959 May 25th, 1960

AGREES OBBSEIN WITH DISCONTINUED

106 »901 (I» i »s« a / au

The invention relates to a contrast filter for differentiating green technical colors (paints, etc.) from natural leaf green (chlorophyll).

It is known that chlorophyll reflects particularly strongly in the near ultra-red, and that much more than in the visible spectral range. This is why this appears when viewed with a UR imager Leaf green white. This effect has entered the literature as the chlorophyll effect. As the eye for distant Red and is also sensitive to near-ultrared, albeit not very much, this effect can also be used can be perceived by the eye, e.g. B, when you look through a suitable red filter. at Viewing through this red filter, however, you get monochrome images and the leaf green contrasts only through a much lighter tint than the colored or black-and-white picture shows: Recently color images are also obtained by photographic means, in which "the chlorophyll in red hues differs from the green hues of technical colors and paints stand out. However, because of the necessary detour via a photographic FrozeB this method is cumbersome and not always applicable, and the contrast depth is also not quite satisfactory..

The object of the invention is to improve the permeability of a filter for free observation with the eye to design in such a way that natural leaf green due to the chlorophyll effect from the green of the technical Colors becomes distinguishable, with certain dyes being used to realize this transmission curve. The permeability curve According to the invention, such a contrast filter has a high and broad maximum with a steeper short-wave Edge in the red and near ultra-red spectral range (approximately from 640 to 760 τπμ.) And a flat one and low secondary maximum at the point of the contrasting color, preferably in the blue and / or violet Spectral area, while in the rest of the visible part of the spectrum, i.e. predominantly in the Green goes to zero. When making comparative observations, it is advisable to keep the Degree of accommodation of the eye to share the filter, e.g. B. in an upper and a lower half, wherein one half has a transmission according to the contrast characteristics described above, the other half However, half receives a neutral gray permeability characteristic of the same or similar attenuation. When observing with the naked eye it is also beneficial to eliminate the disturbing Scattered light and thus for the better. Accommoda-. tion of the eye the filter, or one of two filters To provide existing glasses with a glare shield that is known per se and fits tightly on the face.

»5 contrast filters to distinguish green technical dyes from natural leaf green (chlorophyll)

Patented for:

Research Laboratory University Prof. Dr.-Ing. Walter Heimann, Wiesbaden-Dotzheim.

Dr.-Ing-Walter i leimana and Franz Langhart, Wiesbaden-KohUiedL ₁ have been named as inventors

Fig. 1 shows the transmission curve of such a contrast filter. As can be seen, the main maximum begins 1 with a steep flank 2 at about 640 to 660 m | i and extends with its highest Permeability of more than 80 * / o to the UR. The flat secondary maximum 3 is z. B. in blue or violet spectral range, the maximum permeability here is only a few percent (1 to 3 * / »). That The ratio of the heights of the main maximum to the secondary maximum is determined by the ratio the red reflected by the green to the blue part of the daylight and determines the depth of contrast. A blue secondary maximum that is too low compared to the red permeability maximum provides Very high-contrast, but very weak images, with a smaller ratio, the contrast depth bright images achieved. The remaining parts of the visible spectrum 4 are strongly absorbed; the spectral transmittance in these parts can be kept so low that green colors Just get through with enough strength to contrast well with the bright red of the chlorophyll. Since the eye has the greatest sensitivity precisely in the green spectral range, the spectral transmittance in the spectral range corresponding to the green hues be very low, mostly less than 0.1 · / ·.

Such permeability curves can be obtained with different dyes or combinations of dyes being represented. So you get z. B. BIau-Red Contrasting Filters with Naphthol Blue Black T in appropriate concentrations. During this color

ows-twae

Claims (3)

The substance for a liquid filter alone is sufficient - a concentration of 1: 2200 already delivers Usable filters with a layer depth of 5 mm - it must be combined with other dyes for solid filters will. Solid filters are most easily made as gelafine filters. Bathing gelatinized Glass plates, in dye solutions, is a well known and useful manufacturing method. Be like that good results achieved by a filter combination of two filters according to the manufacturing process mentioned, namely by bathing gelatinized glass plates in 1, 20 to 30 minutes in naphthol blue black T 1: 200 mixed with gentian violet B 1: 500, 2. about 40 minutes in orange G 1: 500. Viewing through these filters preferably shows blue or purple and red color tones. Red and blue stand out very strongly, but the other colors, especially green, are only reproduced in a muted but clearly visible manner. Chlorophyll appears bright red in daylight and forms strong contrasts with the green hues of the technical green lacquers in the predominantly blue environment. In Fig. 2, a filter is shown as it is particularly suitable for comparative observation. This Filter is conveniently divided into two halves, with z. B. the one, lower half 5, a permeability curve according to the contrast characteristic shown in FIG. 1, the other, upper half but consists of a gray filter of suitable permeability. In this case it also remains with comparative Observation preserves the uniform accommodation of the eye so that color comparisons can be made immediately can take place without the eye being overstrained by rapidly following accommodation. When observing with the naked eye, the influence of the scattered light becomes unpleasant and disturbing felt because the eye does not adapt sufficiently to the damping of the filter in its accommodation can. Tight fitting filters and glasses or those with side glare protection are known and sufficient countermeasures to this. These filters are mainly used in the military field. You can take Serve among other things for the detection of camouflaged military objects, since not only technical paint colors do not show the chlorophyll effect, but also cut foliage with the help of this effect is easily distinguishable from fresh foliage. But also for color testing of fabrics and other textiles with regard to their camouflaging properties against night visibility by means of image converters, filters according to the Invention very suitable. Patent application. is 1. Contrast filter to distinguish green technical dyes of natural leaf green, characterized in that the permeability curve a high and wide maximum (1) with a steep short-wave flank (2) at about * o 640 to 760 πιμ in the red and near ultra-red spectral range and a flat and low one Secondary maximum (3) at the point of the contrasting color, preferably in the blue and / or violet Spectral region, and in the remaining part of the ag visible spectrum (4), i.e. mainly at the points of the spectral green towards zero. 2. Filter according to Claiml for comparative observation to maintain the degree of accommodation of the eye, characterized in that the filter is divided into two parts, e.g. into an upper (5) and a lower half (6), one half z. B. (6) the transmittance of the contrast characteristic (1, 2, 3, 4), the other half (S), however, made of a neutral gray filter glass, more suitable There is permeability. 3. Device for color testing with filters according to claims 1 and 2, characterized in that that two similar filters are arranged in a glasses frame, which one on Has face-fitting glare protection, which is expediently the same color and light transmission like the upper half (5) of the filter. 1 sheet of drawings