Device for optically checking documents

Abstract

Device for optical inspection of documents (3, 22, 103, 113, 133), with a light source (9, 79, 119), an observation unit (1, 91, 101, 111; 121, 131) which has a window (2a, 2c; 92, 102; 122) through which the light emitted by the light source (9, 79, 119) for the examination of the documents (3, 22, 103, 113, 133) by an observer (11) exits, and a coupling unit (14, 14a) to introduce the light emitted from the light source (9, 79, 119) from outside into the observation unit (1, 91, 101, 111; 121, 131), characterized by the fact that the window (2a, 2c; 92, 102; 122) contains a fluorescent substance, and the window is formed by a support plate (2a, 2c; 92, 102; 122) which is suitable for supporting the document to be examined (3, 22, 103, 113, 133) in order to transmit the light emerging from the window through the document (3, 22, 103, 113, 133) towards the observer (11).

Description

[0001] German patent application DE 10 2005 022 305 A1 (title: "Crime Scene Light") discloses a cross-sectional converter that uses mirrors to transform a circular spot of light into an elongated, rectangular one, which can be used to detect shoe prints at a crime scene. In this example, a mercury lamp with an extremely high mercury vapor pressure of approximately 200 atmospheres (2 × 10⁻⁶) is used as the light source. 7Pa) is used. The radiation from this lamp, which covers the spectral range of approximately 300 nm to 700 nm, is focused into a liquid light guide. The output radiation from this guide is introduced into the cross-sectional transducer, an internally mirrored, triangular hollow body. This radiation is reflected multiple times within the reflector cavity and exits through a narrow, elongated rectangular window made of Plexiglas, with a relatively homogeneous intensity distribution across the light-emitting surface. The radiation spreads out in a fan shape above the ground and facilitates the detection of faint relief structures such as shoe prints.

[0002] Another example of state of the art is the drawing table with underbody lighting described in US 919 245 A.

[0003] The object of the present invention is to modify the already known cross-sectional transducer for shoe print detection in such a way that it can be used as a document verification device using the transmitted light method. The light source with connected liquid light guide, as described as a crime scene light in patent DE 10 2005 022 305 A1, is to continue to be used as the radiation source, so that the document verification device according to the invention can be defined as an accessory to the crime scene light.

[0004] This problem is solved by the document verification device defined in claim 1 of the present patent. The dependent claims and the collateral claim 17 relate to preferred embodiments and modifications of the device. The details are clarified in the following detailed explanation.

[0005] The specific application of the invention concerns the X-ray examination of sealed envelopes with the possibility of identifying their contents (drugs, explosives, money, texts), as well as the authentication of identity cards, passports, and driver's licenses using transmitted light. The use of a crime scene light as a light source allows the documents to be X-rayed in ten or more different spectral ranges between 300 nm and 700 nm by rotating the filter wheel of the crime scene light, as explained in more detail in application DE 10 2005 022 305 A1.

[0006] The requirement remains that document surfaces up to DIN A4 size must be able to be X-rayed. The light source to be used is the ultra-high-pressure mercury lamp (VIP) found in the familiar crime scene light. ® -lamp or HTV ® - or UHP ®-lamp) are used, whose main emission lies in the spectral range between 300 nm and 500 nm, namely about 70% of the total emission, because this type of lamp currently has the highest efficiency of all gas discharge lamps in terms of the conversion of electrical into optical power.

[0007] For scanning whitish or light-colored documents, the highly blue-heavy radiation of the HTV is used. ® The lamp (manufactured by Osram) works well. For darker-colored documents or envelopes, which are often brownish or grayish, longer-wavelength, i.e., red, radiation would be more advantageous because it penetrates the dark-pigmented paper fibers better than blue radiation. Since the HTV ® Since the lamp has almost no emission in the red spectral range, red bandpass filters have no positive effect when illuminating darker pigmented paper documents.

[0008] Surprisingly, it has been shown that using a red fluorescent plexiglass plate as a support surface for the documents being examined results in a noticeable improvement in contrast. For example, if plexiglass is doped with the strongly red fluorescent dye Lumigen... ® , a dye from the perylene group, thus the incident and absorbed blue radiation, generally radiation from the short-wave main emission range of the HTV ®The crime scene lamp's lamp, emitting light in the 300 nm to 500 nm range, converts it into red radiation in the wavelength range around 630 nm. The quantum efficiency of the blue absorbed radiation is almost 100% for generating red light quanta from the blue absorbed light quanta. In this way, it is possible to convert some of the blue radiation, which is useless for penetrating dark-colored documents or envelopes, into useful, deeper-penetrating red radiation without having to use a new, alternative radiation source with red spectral emission, such as tungsten-halogen or xenon lamps. For viewing the red light, the only necessary surface is the red fluorescent plexiglass plate.

[0009] Such with the dye “Lumogen” ®Red-doped Plexiglas sheets are commercially available. They are typically about 3 mm thick, have a flat, parallel surface with a polished finish, and are distinguished by intensely luminous edges where the red fluorescent light is concentrated. These intensely luminous edges result from the light-guiding effect of the flat, double-sided polished sheets, caused by total internal reflection of the internally generated red fluorescent light at the glass / air interface.

[0010] If such a colored plexiglass plate is used as a document support, one or both of the polished flat surfaces of the plate can be structured, be it by ribbing, roughening, sandblasting or satin finishing, in order to disrupt the light guiding mechanism and obtain more red emission through the flat surface.

[0011] Alternatively, one of the highly intense red glowing edges can be used as a reading line for documents by dragging the document or envelope across the glowing edge to read line by line. When using the light panel in this way, it is recommended to mirror the unused remaining glowing edges of the panel, as well as the outer surface of the panel facing away from the pump radiation, in order to concentrate the highest possible intensity of red light at the reading edge. Mirroring the outer surface of the fluorescent panel, possibly with a thin air gap, allows the unabsorbed blue pump light penetrating the panel to be reversed, thus making better use of the pump radiation.

[0012] A further drastic increase in the transparency of the documents being examined can be achieved by spraying or brushing one or both surfaces of the documents with a suitable immersion fluid during X-ray examination. This principle of moistening the documents during X-ray examination is already known. For example, gasoline, trioxide, or hexane are used as immersion fluids. However, these known fluids have the disadvantage that they can permanently alter the documents, or in the worst case, destroy them, because they dissolve or swell the material. Furthermore, rapid, residue-free evaporation is not guaranteed with these reactive fluids.

[0013] An ideal immersion fluid for document examination should have the following properties: 1. The liquid should be odorless, physiologically harmless, and non-flammable. 2. It should be chemically inert and its molecules should not contain any reactive groups. 3. It should have no solution properties whatsoever. 4. The latent heat of vaporization should be negligible, i.e., practically zero, meaning the molecules should have no dipole moments, i.e., paper soaked with the liquid should dry completely within a few minutes without any lasting traces of swelling, odor, or other changes and residues. 5. The boiling point should be between 60°C and 150°C.

[0014] Perfluorinated or at least partially fluorinated organic liquids, whose molecules consist only of the elements C and F, or C, F and H, or C, F and O or C, F, H and O, have proven to be ideal immersion liquids.

[0015] They should only contain single bonds of the type CF, CH, or CO, i.e., no double bonds. Among these liquids, perfluorinated liquids are preferred. Examples of such liquids include perfluorinated compounds, e.g., primary compounds with eight carbon atoms:

[0016] If the document to be examined is sprayed with such a liquid during X-ray examination, it becomes highly transparent for approximately two minutes, allowing sufficient time for photographic documentation. Pressing a transparent, flat plate onto the X-rayed envelope facilitates the recognition and identification of the writing on a letter sealed inside. Furthermore, placing a magnifying glass with approximately 4x to 10x magnification improves the visibility of writing and other markings.

[0017] The invention is described below using exemplary embodiments. Fig. 1 to 13 explained in more detail. This shows: Fig. 1 a perspective representation of the optical document verification device according to a first embodiment, in which the observation unit mentioned in the claims is realized in the form of a mirror box and the window mentioned in the claims is realized in the form of a support plate; Fig. 2 a cross-sectional view of the first embodiment, wherein three alternative support plates are shown for better illustration; Fig. 3 an enlarged section of the light exit part in the Fig. 2; Fig. 4 the optical document verification device according to the first embodiment with opposite the Fig. 1 modified mounting plate, Fig. 5 a cross-sectional view of the optical document verification device according to a second embodiment, in which the observation unit mentioned in the claims is realized in the form of a light-active magnifying glass and the window mentioned in the claims is realized in the form of two lenses; Fig. 6 an enlarged section of the light exit part in the Fig. 5; Fig. 7 a perspective view of the optical document verification device according to a third embodiment, in which the observation unit mentioned in the claims is in the form of a light-active magnifying glass and the window mentioned in the claims is in the form of two lenses; Fig. 8 a cross-sectional view of a detail of the third embodiment; Fig. 9 a cross-sectional view of a detail of the first embodiment with a difference compared to the Fig. 2. modified internal structure of the mirror box; Fig. 10 a cross-sectional view of a detail of the first embodiment with a difference compared to the Fig. 2 additional reflector attachments; Fig. 11 A perspective view of the optical document verification device according to the first embodiment with the additional reflector attachment as shown in Fig. 10; Fig. 12 a perspective view of the optical document verification device according to a fourth embodiment, in which the observation unit mentioned in the claims is realized in the form of a funnel-shaped light emission device and the window mentioned in the claims is realized in the form of a transparent plate; and Fig. 13 a perspective view of a detail of the light emission device of the fourth embodiment.

[0018] Fig. Figure 1 shows the complete arrangement consisting of the light source (9), the liquid conductor (10), and the internally mirrored box (1) with the support surface (4), which can be the size of a DIN A5 or DIN A4 format. The light source (9) contains the radiation source, consisting, for example, of an HTV. ® - Lamp with an electrical power output of approximately 100 W - 250 W. The radiation from the HTV ® The light from the lamp is focused within the light source (9) by means of a reflector into the liquid light guide (10) and emitted into the inner lumen of the mirror box (1). In the white light range of 300 nm - 700 nm, a total radiant power of approximately 15 W is available inside the mirror box (1).

[0019] The support plate (2a) in this example is one with “Lumogen”. ®A red-doped plexiglass plate, whose surface is smooth or has a ribbed structure. The document, e.g., an envelope (3), which may be brown-pigmented, is placed on this support plate (2a). With full white light illumination inside the mirror box (1), the writing (8) of a letter inside the sealed envelope (3) can be read in the reddish light of the fluorescent plate (2a).

[0020] The legibility of the writing (8) is significantly improved by spraying the envelope (3) with the perfluorinated liquid (5) from the spray bottle (6) and by placing the magnifying glass (7) on it. Turning the knob (9a) rotates a filter wheel inside the light source (9), which is equipped with ten or more bandpass filters in the spectral range between 300 nm and 700 nm. The use of narrowband bandpass filters for X-ray inspection is primarily relevant for verifying the authenticity of identity cards, passports, or driver's licenses, with UV light being of particular importance.

[0021] Fig. Figure 2 shows a cross-section of the interior of the mirror box (1). The fluid conductor (10) emits the radiation (13) into the interior volume of the mirror box (1). The radiation (13) strikes a mirror (12), which in this example is tilted (e.g., a highly reflective aluminum plate), and is reflected by it onto the transparent or fluorescent document support plate (2a, 2b, 2c). Three support plates are shown in the figure to illustrate their interchangeability. In this embodiment, however, only one plate is used.

[0022] The side walls and base plate of the mirror box (1) are also highly reflective in the inner lumen, although the inclined mirror plate (12) may be omitted. In any case, all radiation is transmitted to the outside through the transparent or fluorescent support plate (2a, 2b, 2c).

[0023] The light-emitting part (14) of the liquid light guide (10) is in Fig. Figure 3 shows in more detail. The radiation emitted by the light guide (10) strikes a diffuser plate (17) made of heat-resistant, UV-transmitting glass, which is roughened on both surfaces (15, 16), before entering the inner lumen of the mirror box (1). This ensures that the radiation leaving the light guide (10) with a divergence angle of only approximately 60° becomes highly divergent, so that the document printing surface of the plate (2a, 2b, 2c) is illuminated sufficiently homogeneously.

[0024] The diffuser plate (17), which may be roughened on only one side, is crimped into a sleeve (14a), which in turn is placed onto the light exit window of the light guide (10). If roughening of the diffuser (17) on only one side is sufficient for homogeneous illumination of the document, the diffuser plate (17) can be omitted, and the light exit surface of the liquid light guide (10), which is made of quartz glass, can itself be roughened.

[0025] One-sided or no roughening of the light-emitting surface is possible if the mirror box (1) is smaller, with a document holder the size of identity cards, driver's licenses, or banknotes. The mirror box (1) should not be larger than necessary, because the intensity of the radiation available for scanning the documents will then always be at its maximum.

[0026] Fig. Figure 2 shows, for example, three different options for a document support plate (2a, 2b, 2c). The plate (2a) consists of a 3 mm thick Plexiglas sheet with a textured surface on at least one side. The plate measures, for example, 150 mm x 200 mm. The Plexiglas sheet (2a) is doped with the dye "Lumogen". ® red”, a red fluorescent dye, with excitation or absorption in the wavelength range of approximately 300 nm - 500 nm. Instead of “Lumogen”. ® “red” can also be “Lumogen” ® orange” or “Lumogen” ® yellow” can be used.

[0027] Instead of Plexiglas, another transparent medium can be used for the mounting plate, such as glass, polycarbonate, or another transparent plastic. Structuring one of the two surfaces of the plate (2a) can also be omitted, especially with higher dye doping concentrations, if the edges no longer glow. The fluorescent dye can also be applied as a thin layer to the underside of the transparent mounting plate, even as a powder layer. Instead of Lumigen ® Other fluorescent dyes, such as rhodamines, metal oxides or transition metal oxides, can also be used.

[0028] The surface ribbing, roughening, or satin finishing of the plate (2a) ensures that slightly more fluorescence radiation is available for transmission, because a larger proportion of the fluorescence radiation concentrates at the edges of the plate. For this reason, it is advantageous to mirror these four luminous edges so that the concentrated fluorescence radiation striking them is reflected back into the inner lumen of the plate. The surface of the fluorescent plate (2a) can be structured by ribbing, sandblasting, or satin finishing, either on one or both sides.

[0029] The support plate (2b) is an example of a non-fluorescent plate. It is completely transparent across the entire spectral range of the radiation, i.e., in the spectral range from 300 nm to 700 nm. UV-transmitting Plexiglas with a thickness of 3 mm is very suitable, but a glass plate, e.g., made of borofloat, can also be used.

[0030] The non-fluorescent transparent support plate (2b) is used for the X-ray examination of non-pigmented white documents, such as a white envelope (3) containing a document (8). As already described, the viewer (11) can significantly facilitate the recognition of details by using a magnifying glass (7) and the fluorinated immersion fluid (5), which is applied via the spray bottle (6).

[0031] The third alternative support plate (2c) is again a fluorescent plate, like plate (2a), but in this plate only one of the intensely luminous edges is used for reading letters with dark pigmentation. It is described in more detail in Fig. Figure 4 shows a fluoroscopy arrangement according to the invention, in which the extremely bright luminous edge (20) of a luminogen ®The doped Plexiglas plate (2c) is used as a reading line. All other edge surfaces, as well as the outer surface of the plate (2c), are metallically mirrored, so that a maximum intensity of the fluorescence radiation (19) emerging at the reading edge (20) is achieved.

[0032] The sealed envelope (3) containing the document (8) is pulled across the luminous edge (20) so that the document (8) can be read line by line. The luminous edge (20) can also be beveled and polished to provide a slightly wider reading line. The thickness of the fluorescent plate should be in the range of 2–10 mm. The magnifying glass (7) and the immersion fluid (5) can also be used to support this arrangement, similar to the procedure described in [reference to be added]. Fig. 1.

[0033] For the sake of completeness, a possible variant is mentioned here in which the fluorescence is not coupled into the mirror box (1) with red fluorescent mounting plate (2a) from an external light source via a light guide, but the mirror box itself is the radiation source in the form of one or more HTVs. ® -contains lamps. Instead of the HTV ® -Lamps can also contain other low-red light radiation sources such as low-pressure mercury lamps, such as energy-saving lamps or tungsten-halogen lamps, in the mirror box, with the red fluorescent support plate (2a) increasing the red light component important for illumination.

[0034] Fig. Figure 5 shows a detailed illustration of the magnifying glass with the two lenses (21) belonging to the optical inspection device according to the invention. This magnifying glass is placed on the document, which is illuminated from below, to improve detail recognition. The tubular outer casing of the magnifying glass (7) should be made of an opaque material, i.e., black, so that the ambient daylight, which would interfere with the contrast, does not affect the observation. Otherwise, the observation room would have to be darkened. If the magnification effect of the magnifying glass is not required, a black, elongated tube (not shown here) can simply be placed on the document to act as an "artificial darkroom." This eliminates the need for external darkening.

[0035] According to the second embodiment, the observation magnifying glass can itself also have a light-activated function (see Fig. 5), i.e., it can be permeated internally with the radiation (13) which, in addition to the transmitted light from the mirror box, produces reflected light for the document (22). Such combined bi-sided irradiation of a document can be useful, for example, in searching for fluorescent markers on banknotes using UV light. A light-activated magnifying glass can be produced, for example, with the aid of a second, external light source (9), the radiation from the second light source being irradiated in a similar way to that of the mirror box (see Fig. 2 and Fig. 3) via a liquid light (10) is introduced into the inner lumen of the magnifying glass. In Fig. 6 is shown in an analogous manner as with the mirror box, as here too with the magnifying glass the output radiation of the light guide is homogenized and made highly divergent by placing a diffuser plate (17) roughened on both sides (15, 16) with UV transmittance in front of it at the light exit end of the sleeve (14a).

[0036] In this way, the light-active magnifying glass can also be adjusted by turning the filter wheel (9a in Fig. 1) in the light source (9) with different spectral ranges. When observing in fluorescence, an optical long-pass filter (not shown here) is placed on the magnifying glass, which blocks the short-wavelength excitation radiation and transmits the long-wavelength fluorescence radiation. For the sake of completeness, it should be mentioned here that the light-activated magnifying glass described above is also useful for visualizing and documenting minimal traces at a crime scene, such as fingerprints or bodily fluids, fibers, or skin particles, in both white light and fluorescence observation.

[0037] The Fig. 7 and Fig. Figure 8 shows the third embodiment, namely a so-called mousehole aperture (71) docked to the lamp, which generates a two-dimensional fan of light that tangentially illuminates the observation plane of the magnifying glass (77), thus clearly highlighting even the smallest irregularities or relief structures on the surface of the document to be examined, in addition to the transmitted light method. An example of its application is embossed lettering on paper.

[0038] Fig. Figure 7 shows an overview arrangement consisting of the light source (79), the light guide (710), the actual aperture (71) with the horizontal slit-shaped mousehole opening (72), cooling fins (76), and the docking pins (73). The docking pins connect the aperture (71) to the magnifying lens (77) with the corresponding receiving apertures (75) and the corresponding slit-shaped opening (74), which is approximately congruent with the opening (72). The opening (72) has a width of 25 mm and a height of only 3 mm and is located very close, only a few tenths of a millimeter, above the base of the aperture. The light guide (710) is secured by a locking screw (88). The normal insertion sleeve (714) provided for the light guide remains unused in this particular grazing light observation. The fiber optic cable can be easily repositioned depending on which viewing method is preferred, whether with light incident obliquely from above or grazing.

[0039] Fig. Figure 8 shows a cross-sectional view of the aperture (81) docked to the magnifying glass (87) by means of the docking pins (83), and it can be seen that the light fan (813) contains only a small portion of the radiation beam emitted by the light guide (810). The unused radiation is absorbed by the walls of the aperture cavity (85). These walls are therefore completely blackened so that no highly divergent radiation enters the magnifying glass chamber through the mouse hole opening (82 or 84). Since the aperture (81) absorbs most of the radiation, cooling fins (86) are provided on the upper surface of the aperture.

[0040] Regardless of its use in connection with the document testing device, it has been shown that the magnifying glass with the tangentially incident grazing light can be very useful for general forensic tasks, such as the representation of fingerprints on dusty surfaces, fibers, skin flakes and other traces that only stand out minimally above the base surface.

[0041] Fig. Figure 9 shows a mirror box (91) with highly reflective inner walls and without an inclined mirror plate. The light guide (910) is mounted in the mirror box (91) at an angle of approximately 45°, so that it initially illuminates the base plate of the box. The radiation then reaches the mounting plate (92) by multiple reflections at the side walls. The mounting plate can be transparent or coated with absorbing or fluorescent dyes. This arrangement results in particularly homogeneous illumination of the mounting plate (92).

[0042] Fig. Figure 10 shows a section of a mirror box (101) with a box-shaped rectangular reflector attachment (104) with internally mirrored walls, which is mounted on the support plate (102). The reflector attachment (104) remains open on at least one side for loading and viewing. This attachment allows documents (103), such as passports, to be illuminated from both above and below simultaneously to better identify internal watermarks or fluorescent markers.

[0043] Fig. Figure 11 shows the overall view of the mirror box (111) with the reflector attachment (114) for double-sided viewing of a document (113), such as an identity card, etc., including liquid light guide (1110) and light source (119).

[0044] Fig. 12 and Fig. Figure 13 shows the fourth embodiment, which enables a particularly intensive and flexible X-ray transmission unit for the rapid inspection or sorting of documents. As a light emission device, a funnel (121) is attached to the light emission end of the liquid light guide (1210), the open end of which is covered by a transparent plastic or glass plate (122) or a plate doped with dyes or fluorescent dyes.

[0045] The funnel is advantageously mirrored on the inside. The diameter of the support plate (122) is only about 5 to 15 cm, so the intensity of the emitted light is very high. To reduce the glare somewhat, a Plexiglas plate (122) doped with the perylene dye "Lumogen" is recommended. ® red".

[0046] Fig.Figure 13 shows such a X-ray funnel (131) when viewing a document in the form of a written piece inside a closed envelope (133). Reference symbol list Boxes 1, 91, 101, 111 2a-c, 92, 102 support plates 3, 22, 103, 113, 133 Document 4 Support surface 5 Liquid 6 spray bottles 7, 77, 87 magnifying glass 8 Font 9, 79, 119 Light source 9a Rotary knob 10, 710, 810, 910, 1110, 1210 fiber optic cable 11 observers 12 mirrors 13,813 radiation 14 Light output part 14a, 714 Sleeve 15, 16 surfaces 17 diffuser plates 19 Fluorescence radiation 20 edge 21 lenses 71, 81 aperture 72, 82 Opening 73, 83 docking pins 74, 84 Opening 75 receiving ports for docking pins 76, 86 cooling fins 85 aperture cavity 88 Locking screw 104, 114 Reflector attachment 121, 131 funnels 122 transparent plates

Claims

[1] Device for optically checking documents (3, 22, 103, 113, 133), with a light source (9, 79, 119), an observation unit (1, 91, 101, 111; 121, 131) which has a window (2a, 2c; 92, 102; 122) through which the light emitted by the light source (9, 79, 119) for the examination of the documents (3, 22, 103, 113, 133) by an observer (11) exits, and a coupling unit (14, 14a) to introduce the light emitted from the light source (9, 79, 119) from outside into the observation unit (1, 91, 101, 111; 121, 131), characterized by , that the window (2a, 2c; 92, 102; 122) contains a fluorescent substance, and the window is formed by a support plate (2a, 2c; 92, 102; 122) which is suitable for supporting the document to be examined (3, 22, 103, 113, 133) in order to transmit the light emerging from the window through the document (3, 22, 103, 113, 133) towards the observer (11). [2] Device according to claim 1, wherein the light source (9, 79, 119) and the observation unit (1, 91, 101, 111; 121, 131) are connected by an optical fiber (10, 910, 1110, 1210) designed to direct the light from the light source (9, 79, 119) to the coupling unit (14, 14a). [3] Device according to claim 2, wherein the light guide (10, 910, 1110, 1210) preferably consists of a flexible tube with a liquid, light-conducting core. [4] Device according to one of the preceding claims, wherein the coupling unit (14, 14a) has a sleeve (14a) attached to a side wall of the observation unit (1, 91, 101, 111). [5] Device according to one of the preceding claims, wherein a diffuser (17) is attached at the light output end of the coupling unit (14, 14a) for widening and homogenizing the light beam. [6] Device according to one of the preceding claims, wherein the support plate (2a, 2c; 122) is made of a transparent medium, such as Plexiglas, glass or polycarbonate, which is doped with the fluorescent substance. [7] Device according to one of the preceding claims, wherein the top surface and at least one side edge of the support plate (2c) are mirrored, so that the support plate (2c) allows the light to exit only horizontally at the at least one non-mirrored side edge (20). [8] Device according to claim 7, wherein the at least one non-mirrored side edge (20) is chamfered. [9] Device according to one of the preceding claims, wherein the observation unit is formed by a box (1, 91, 101, 111) which has one or more mirrors (12) inside to allow the light emitted by the light source (9, 119) to exit the box (1, 91, 101, 111) through the window (2a, 2c; 92, 102). [10] Device according to one of the preceding claims, further comprising a reflector attachment (104, 114) which can be placed on the support plate (102) to form a cavity between the reflector attachment (104, 114) and the support plate (102) for the document (103, 113) to be tested, wherein the top surface facing the support plate (102) and / or at least one side wall of the reflector attachment (104, 114) are internally mirrored, so that the light emitted from the light source (9, 119) is reflected thereon and the document to be examined (103, 113) can also be illuminated from its top surface, and wherein the reflector attachment (104, 114) has an observation opening through which the observer (11) can view the document (103, 113) for inspection purposes. [11] Device according to one of the preceding claims, further comprising a magnifying glass (7; 77; 87) which can be placed on the document (3, 22) to be examined for magnification purposes. [12] Device according to claim 11, wherein the magnifying glass (7; 77; 87) has one or more lenses (21), Light emitted from the light source (9, 79) is coupled through a side wall of the magnifying glass (7; 77; 87), and The magnifying glass (7; 77; 87) is designed to be placed on the document (3, 22) to be examined with the side opposite the lenses (21) so that the coupled light can be reflected from the document (3, 22) and exit the magnifying glass (7; 77; 87) through the lenses (21) in the direction of the observer (11). [13] Device according to claim 12, comprising an aperture (71, 81) to widen the light coupled in through the side wall of the magnifying glass (77; 87) two-dimensionally along a plane parallel to the lens (21). [14] Device according to claim 13, wherein the aperture (71, 81) has docking pins (73) for fixing to corresponding receiving openings (75) on a side wall of the magnifying glass (77; 87) and / or cooling fins (76). [15] Device according to claim 13 or 14, wherein the light emitted by the light source (79) can be coupled in either through the aperture (71, 81) or a sleeve (714) attached to a side wall of the magnifying glass (77, 87). [16] Device according to one of claims 1 to 3, wherein the observation unit is formed by a funnel-shaped light emission device (121, 131). [17] Device for optically inspecting documents (3, 103, 113, 133), comprising an observation unit (1, 91, 101, 111) containing a light source and a window (2a, 2c; 92, 102) through which light emitted from the light source for inspection of the documents (3, 103, 113, 133) by an observer (11), characterized by , that the window (2a, 2c; 92, 102) contains a fluorescent substance. [18] Device according to any of the preceding claims, wherein the fluorescent substance is a fluorescent perylene compound, such as a dye from the group of luminogens® , is. [19] Device according to one of the preceding claims, wherein the fluorescent material is designed to fluoresce in the longer-wavelength yellow-red-infrared range when irradiated with light in the short-wavelength ultraviolet-blue-green range.

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