Track physical evidence photographing device

Abstract

The utility model provides a trace material evidence photographing device, which can realize that the imaging size does not change along with the change of the photographing distance, does not need to calibrate an electronic scale repeatedly during use, avoids pollution or damage of potential material evidences on an object, and enables the field investigation trace material evidence photographing work to be more convenient, efficient and safe. The camera part of the built-in camera equipment in adaptive connection comprises a camera lens and a photosensitive element, the trace material evidence photographing device comprises a box body, a material detection hole and a photographing hole are formed in the box body, and an imaging objective lens arranged on an imaging light path between the material detection hole and the photographing hole is arranged in the box body; the camera lens, the photographing hole, the imaging objective lens, the material detection hole and the optical axis of the imaging light path are coaxially arranged, and the camera lens is located on the focus of the imaging objective lens, so that a trace material evidence located below the material detection hole is imaged on the photosensitive element.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of forensic science technology, specifically trace evidence photographic device. BACKGROUND

[0002] When the handprint, biological material and other trace evidence are found in the criminal case scene investigation, in order to truly reflect the shape, position and size of the trace evidence, it is necessary to place a ruler beside the trace evidence, and then use a professional camera to take a picture and fix it.

[0003] With the continuous increase of effective pixels of the photosensitive element of the built-in camera device of the smart phone or the tablet computer and the continuous improvement of the lens performance, the built-in camera device can also replace the professional camera for taking pictures and fixing the trace evidence. By developing a special photographic software for the built-in camera device, an electronic ruler can be synthesized on the photo, which has the beneficial effects that the physical ruler can be replaced, and the potential evidence that may exist at the place where the physical ruler is placed can be avoided from being polluted or damaged.

[0004] Generally speaking, the closer the camera is to the object, the larger the imaging of the object on the camera photosensitive element; the farther the camera is from the object, the smaller the imaging of the object on the camera photosensitive element, and the photographing distance refers to the distance between the camera or the photographic device and the trace evidence during the scene investigation; under the condition that the magnification of the camera is unchanged, the shorter the photographing distance, the larger the imaging of the trace evidence on the camera screen; the longer the photographing distance, the smaller the imaging of the trace evidence on the camera screen. The built-in camera device with the electronic ruler photographic software usually places a physical ruler at a certain fixed photographing distance before taking a picture to calibrate the electronic ruler, then takes a picture and fixes the trace evidence at the same photographing distance, and finally synthesizes the electronic ruler on the photo. If the photographing distance changes, the imaging size of the trace evidence on the camera photosensitive element will also change, at this time, if the electronic ruler is needed, the electronic ruler must be recalibrated at the new photographing distance, and the trace evidence must be taken again under the condition that the photographing distance remains unchanged, which is very inconvenient to use.

[0005] In order to avoid the tedious work of calibrating the electronic scale, if the electronic scale is calibrated at a certain photographing distance, and the trace evidence is photographed at the same photographing distance, the electronic scale does not need to be calibrated. At present, the simplest and most effective method is to mount the built-in camera device on a photographing device, and calibrate the electronic scale by allowing the photographing device to be close to the real scale, that is, the photographing distance is 0. In the future, the photographing device is always kept close to the trace evidence, that is, the photographing distance is always kept as 0, so that the electronic scale does not need to be calibrated. Although the method of allowing the photographing device to be close to the trace evidence for photographing can solve the problem of repeated calibration of the electronic scale, it introduces two disadvantages: first, when the photographing device is close to the trace evidence for photographing, the photographing device will contact the bearing object of the trace evidence to a certain extent, which may contaminate or damage the potential evidence at the contact position of the object; second, some trace evidence cannot be close to the photographing device for photographing, such as the fingerprints on the glass close to the window frame, which cannot be close to the photographing device for photographing due to the obstruction of the window frame with a certain thickness.

[0006] Therefore, the application provides a trace evidence photographing device, which can realize that the imaging size does not change with the change of the photographing distance, does not need to be calibrated during use, and can realize non-contact photographing to avoid contamination or damage of potential evidence, so that the photographing and fixing work of trace evidence in the scene investigation is more convenient, efficient and safe, and has great significance for the photographing and fixing work of trace evidence in the crime scene. Content of the utility model

[0007] In view of the above problems, the utility model provides a trace evidence photographing device, which can realize that the imaging size does not change with the change of the photographing distance, does not need to be calibrated during use, and can avoid contamination or damage of potential evidence on the object, so that the photographing work of trace evidence in the scene investigation is more convenient, efficient and safe.

[0008] The technical scheme of the utility model is as follows: a trace evidence photographing device is connected with a built-in camera device, the camera part of the built-in camera device comprises a camera lens and a photosensitive element, the trace evidence photographing device comprises a box body, the box body is provided with a sample hole and a photographing hole, characterized in that: the box body is provided with an imaging objective lens arranged in an imaging light path between the sample hole and the photographing hole; the camera lens, the photographing hole, the imaging objective lens, the sample hole and the optical axis of the imaging light path are coaxially arranged, and the camera lens is located at the focal point of the imaging objective lens, so that the trace evidence below the sample hole is imaged on the photosensitive element, and the ratio of the optical imaging length of the trace evidence to the length of the trace evidence is equal to the ratio of the distance between the camera lens and the photosensitive element to the focal length of the imaging objective lens.

[0009] Further, the built-in camera device is arranged at the top end of the box, the photographing hole is arranged at the top of the box, and the sample hole is arranged at the bottom of the box.

[0010] Further, the imaging objective lens is located directly above the sample hole, and the photographing hole is located directly above the imaging objective lens.

[0011] Further, the trace evidence is imaged on the photosensitive element, and the ratio of the optical imaging length of the trace evidence to the length of the trace evidence is equal to the ratio of the distance between the camera lens and the photosensitive element to the focal length of the imaging objective lens.

[0012] Further, a reflecting assembly is arranged on the imaging light path in the box, the reflecting assembly comprises a first reflecting mirror and a second reflecting mirror, the imaging objective lens is arranged on the imaging light path between the first reflecting mirror and the second reflecting mirror, the first reflecting mirror is located directly above the sample hole, and the second reflecting mirror is located directly below the photographing hole.

[0013] Further, the first reflecting mirror forms a 45° angle with the horizontal plane, so as to reflect the imaging light path optical axis entering the box through the sample hole into the imaging objective lens in a horizontal direction; and the second reflecting mirror forms a 135° angle with the horizontal plane, so as to reflect the imaging light path optical axis in the horizontal direction into the photographing hole in a vertical upward direction.

[0014] The utility model discloses a trace evidence imaging device, which comprises a box body, a camera lens, a photosensitive element, an imaging objective lens, a sample hole, a photographing hole and a trace evidence. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is the structural schematic diagram of the utility model embodiment one.

[0016] Figure 2 It is the trace evidence imaging schematic diagram of Figure 1 .

[0017] Figure 3 It is the structural schematic diagram of the utility model embodiment two.

[0018] Figure 4 It isFigure 3 A schematic diagram of trace evidence imaging;

[0019] Figure 5 This is a schematic diagram of the secondary reflection imaging principle of Embodiment 2 of this utility model;

[0020] Figure 6 These are the imaging principle diagrams for the case where the PD (photographing distance) is relatively short in Examples 1 and 2;

[0021] Figure 7 These are the imaging principle diagrams for cases where the PD (photographing distance) is relatively long, as shown in Examples 1 and 2.

[0022] Figures 1-7 In the middle: 1. Box body; 2. Camera aperture; 3. Sample aperture; 4. Imaging objective lens; 5. Camera lens; 6. Photosensitive element; 7. Built-in camera equipment; 8. Object; 9. Trace evidence; 10. First reflector; 11. Second reflector; 12. Imaging ray; 13. Imaging ray path and optical axis. Detailed Implementation

[0023] The technical solutions and beneficial effects of the embodiments of this utility model will be described in detail below with reference to the accompanying drawings. The described embodiments are merely some embodiments of this utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the protection scope of this utility model.

[0024] Example 1

[0025] like Figure 1 , Figure 2 As shown, this utility model discloses a trace evidence photographing device, which is adapted and connected to a built-in camera device 7. The camera part of the built-in camera device 7 includes a camera lens 5 and a photosensitive element 6. The trace evidence photographing device includes a housing 1, which has a sample hole 3 and a photographic hole 2. An imaging objective lens 4 is installed in the housing 1 and placed on the imaging optical path between the sample hole 3 and the photographic hole 2. The camera lens 5, the photographic hole 2, the imaging objective lens 4, the sample hole 3 and the optical axis 13 of the imaging optical path are all coaxially arranged, and the camera lens 5 is located at the focal point of the imaging objective lens 4, so that the trace evidence 9 located below the sample hole 3 is imaged on the photosensitive element 6, and satisfies the following: the ratio of the optical imaging length h2 of the trace evidence 9 to the length h1 of the trace evidence 9 is equal to the ratio of the distance u between the camera lens 5 and the photosensitive element 6 to the focal length f of the imaging objective lens 4, that is, h2÷h1=u÷f.

[0026] The built-in camera device 7 is arranged at the top end of the box 1, the photographing hole 2 is arranged at the top of the box 1, and the sample hole 3 is arranged at the bottom of the box 1; the imaging objective 4 is located directly above the sample hole 3, and the photographing hole 2 is located directly above the imaging objective 4; the trace evidence 9 is attached to the object 8, and the sample hole 3 is located directly above the object 8.

[0027] The working principle of the embodiment one of the utility model is: Figure 2 As shown in the figure, the trace evidence 9 attached to the object 8 is indicated by an arrow, the bottom of the arrow is located on the optical axis 13 of the imaging light path, and the arrow emits light under the irradiation of a light source (not shown in the figure) and forms an image through the trace evidence photographing device; specifically, taking the top end of the arrow as an example, the top end of the arrow (that is, the trace evidence 9) emits a plurality of light rays (not shown in the figure), and a part of the light rays that pass through the imaging objective 4 begin to converge towards the camera lens 5; the light rays that pass through the camera lens 5 finally converge to a point on the photosensitive element 6; then further taking a light ray emitted by the top end of the arrow as an example, the imaging light ray 12 parallel to the optical axis 13 of the imaging light path enters the box 1 through the sample hole 3, the imaging light ray 12 changes direction through the refraction of the imaging objective 4, so that the imaging light ray 12 is no longer parallel to the optical axis 13 of the imaging light path, but linearly moves towards the focal point of the imaging objective 4; the camera lens 5 and the photographing hole 2 are coaxially arranged with the optical axis 13 of the imaging light path, and the camera lens 5 is located at the focal point of the imaging objective 4, so that the imaging light ray 12 linearly moves towards the focal point of the imaging objective 4 and forms an image on the photosensitive element 6 without refraction when passing through the center point of the camera lens 5.

[0028] As shown in the figure, Figure 2 , Figure 6 , Figure 7 The optical principle of the utility model is:

[0029] The distance between the trace evidence 9 and the sample hole 3 at the bottom of the box 1 is PD, that is, the photographing distance;

[0030] The distance between the imaging objective 4 and the camera lens 5 is recorded as f, that is, the focal length of the imaging objective 4, which is a constant;

[0031] The distance between the camera lens 5 and the photosensitive element 6 is recorded as u, which is a constant;

[0032] The intersection point of the imaging objective 4 and the imaging light ray 12 is recorded as A;

[0033] The intersection point of the imaging objective 4 and the optical axis 13 of the imaging light path is recorded as B;

[0034] The intersection point of the camera lens 5 and the optical axis 13 of the imaging light path is recorded as O;

[0035] The intersection point of the photosensitive element 6 and the imaging light ray 12 is recorded as C;

[0036] The intersection of the photosensitive element 6 and the imaging optical axis 13 is denoted as D;

[0037] Since the camera lens 5 is located at the focal point of the imaging objective 4, the intersection O overlaps the focal point of the imaging objective 4, that is, the length of BO is equal to f;

[0038] The distance from the imaging optical axis 13 to the arrowhead top end of the trace evidence 9 is denoted as h1, that is, the length of the arrowhead of the trace evidence 9, representing the lateral dimension of the object;

[0039] The distance from the imaging optical axis 13 to the arrowhead top end on the photosensitive element 6 is denoted as h2, that is, the length of the arrowhead image, representing the lateral dimension of the image;

[0040] Specifically, the trace evidence 9 is represented by an arrowhead, the bottom of the arrowhead is located at the imaging optical axis 13, and the top of the arrowhead emits many light rays under the irradiation of a light source (not shown in the figure). Taking one of the imaging light rays 12 as an example, the imaging light ray 12 is parallel to the imaging optical axis 13, and according to the basic optical principle that parallel light converges to a focal point through a convex lens, the imaging light ray 12 entering the box 1 through the examination hole 3 travels straight along the AO direction after refraction at the intersection A. Since the intersection O is both the focal point of the imaging objective 4 and the center point of the camera lens 5, according to another basic optical principle that light rays travel straight through the center point of the lens, the imaging light ray 12 continues to travel straight in the original direction after passing through the intersection O, until it reaches the intersection C, that is, the length h2 of the arrowhead image is formed. Whether according to the imaging principle in the case of a short shooting distance PD as shown in Figure 6 or according to the imaging principle in the case of a long shooting distance PD as shown in Figure 7 the imaging light ray 12 emitted by the trace evidence 9 has to pass through the intersection A, that is, the length of AB is always equal to the length of the arrowhead h1 and does not change with the shooting distance PD. Since the camera lens 5 is located at the focal point of the imaging objective 4, the distance between the camera lens 5 and the imaging objective 4 is equal to the focal length f of the imaging objective, then after determining the type of imaging objective according to the situation, the focal length f is a fixed value, and since the camera lens 5 and the photographing hole 2 are coaxially arranged with the imaging optical axis, then Figure 6BOD is a straight line, the light AO through O point does not occur refraction, still along the straight line direction until the intersection C, then AOC is also a straight line, therefore, according to ∠AOB=∠COD, and ∠ABO=∠CDO=90°, the ΔAOB and the ΔCOD have two angles same, the third angle is certainly same, therefore ΔAOB and ΔCOD are similar triangles, CD÷AB=OD÷OB, so h2÷h1=u÷f, wherein focal length f and distance u are fixed constant, so h2÷h1 The value of is also a fixed constant, that is, the optical magnification (the lateral dimension ratio of image and object) is a fixed constant, then regardless of the photographing distance PD between the bottom of the box body 1 and the trace evidence 9, the imaging size of the trace evidence 9 is always unchanged.

[0041] Embodiment two

[0042] As Figure 3 shown, the embodiment two of the utility model differs from the embodiment one in that: the imaging light path in the box body 1 is equipped with the reflecting optical device, specifically, the reflecting assembly is arranged on the imaging light path in the box body 1, the reflecting assembly includes the first reflector 10, the second reflector 11, the imaging objective 4 is arranged on the imaging light path between the first reflector 10 and the second reflector 11, the first reflector 10 is located directly above the examination hole 3, the second reflector 11 is located directly below the photographing hole 2, the first reflector 10 is 45 ° angle with the horizontal plane, to reflect the vertical upward imaging light path optical axis 13 that enters the box body 1 through the examination hole 3 into the horizontal direction and enters the imaging objective 4, the second reflector 11 is 135 ° angle with the horizontal plane, to reflect the horizontal direction imaging light path optical axis 13 into the vertical upward direction and enter the photographing hole 2.

[0043] The working principle of the embodiment two of the utility model is as follows: Figure 4As shown, the test hole 3 is located directly above the object 8, and the trace evidence 9 attached to the object 8 is indicated by an arrow, the bottom of the arrow is located on the optical axis 13 of the imaging light path, and the arrow emits light under the irradiation of a light source (not shown in the figure) and is imaged by a trace evidence camera device; Specifically, taking the top end of the arrow as an example, the top end of the arrow (that is, the trace evidence 9) emits a plurality of light rays (not shown in the figure), of which the light rays that are reflected by the first mirror 10 to reach and pass through the imaging objective 4 are reflected by the second mirror 11 again, and the light rays that pass through the camera lens 5 are finally converged into a point image on the photosensitive element 6; Subsequently, further taking a light ray emitted from the top end of the arrow as an example, the imaging light ray 12 parallel to the imaging light path optical axis 13 enters the box body 1 through the test hole 3, the imaging light ray 12 remains parallel to the imaging light path optical axis 13 after being reflected by the first mirror 10, and reaches the imaging objective 4, the direction of the imaging light ray 12 is changed by refraction of the imaging objective 4, so that the imaging light ray 12 is no longer parallel to the imaging light path optical axis 13, but straightly moves towards the focal point of the imaging objective 4 until entering the second mirror 11 directly below the photographing hole 2, and reaching the focal point of the imaging objective 4 through the reflection of the second mirror 11, the camera lens 5 and the photographing hole 2 are coaxially arranged with the imaging light path optical axis 13, and the camera lens 5 is located at the focal point of the imaging objective 4, so that the imaging light ray 12 straightly moving towards the focal point of the imaging objective 4 does not refract when passing through the center point of the camera lens 5, but still straightly moves and is imaged on the photosensitive element 6.

[0044] As Figure 5 shown, the optical principle of the second embodiment of the utility model is the same as that of the first embodiment, specifically, the trace evidence 9 can form a first virtual image 9' through the first mirror 10, the first virtual image 9' forms a second virtual image 9'' through the second mirror 11, and the imaging objective 4 can form a third virtual image 4'' through the second mirror 11, and the third virtual image 4'' is located directly above the second virtual image 9''; Therefore, in the second embodiment, the two parallel mirrors are placed to image, which is equivalent to that the light emitted from the second virtual image 9'' passes through the third virtual image 4'', then enters the photographing hole 2, and finally is imaged by the camera, that is, the same optical path imaging principle is adopted in the first embodiment and the second embodiment; As can be known from the above description, the optical path imaging principle of the second embodiment can refer to Figure 6 and Figure 7 , and the optical magnification (the ratio of the lateral size of the image to that of the object) in the second embodiment is still h2÷h1=u÷f, wherein the focal length f and the distance u are both fixed constants, so the optical magnification is still a fixed constant, and no matter how the photographing distance PD between the bottom of the box body 1 and the trace evidence 9 changes, the imaging size of the trace evidence 9 is always unchanged.

[0045] In conclusion, the trace evidence photographing device has the advantages that the camera lens 5 is arranged on the focal point of the imaging objective 4, the optical magnification (the ratio of the horizontal size of the image to the object) remains unchanged with the change of the photographing distance, the trace evidence at the scene can be photographed with different photographing distances, and the imaging size of the trace evidence remains unchanged, so that the problem that the electronic scale needs to be recalibrated once the photographing distance is changed when the photographing is performed by replacing the physical scale with the electronic scale is solved, the electronic scale does not need to be calibrated, the potential evidence on the object can be avoided from being polluted or damaged, the photographing work of the trace evidence at the scene is more convenient, efficient and safe, the small invention solves the big problem, and the photographing and fixing of the trace evidence at the crime scene has novelty, creativity and practicality.

[0046] Compared with the first embodiment, the second embodiment is provided with two optical reflecting devices, the first reflecting mirror 10 and the second reflecting mirror 11, in the imaging light path, and the second embodiment can obtain the beneficial effects of reducing the height of the photographing device, making the photographing device more compact and convenient to use, in addition to the beneficial effects of the first embodiment; in addition, the box body 1 is not limited to the shape structure in the first embodiment and the second embodiment.

[0047] For those skilled in the art, it is obvious that the utility model is not limited to the details of the above-mentioned exemplary embodiments, and the utility model can be realized in other specific forms without departing from the spirit or basic characteristics of the utility model. For example, the imaging objective 4 is arranged between the sample hole 3 and the first reflecting mirror 10 by changing the second embodiment, and the same effect as the utility model can be obtained, therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-limiting, the scope of the utility model is defined by the appended claims instead of the above description, therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the utility model. Any reference signs in the claims should not be regarded as limiting the claims.

[0048] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description manner of the specification is only for the sake of clarity, those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can be combined appropriately to form other embodiments that can be understood by those skilled in the art.

Claims

1. A trace evidence photographing device, adapted and connected to a built-in camera device, wherein the camera portion of the built-in camera device includes a camera lens and a photosensitive element, and the trace evidence photographing device includes a housing, wherein the housing is provided with an examination hole and a photographing hole, characterized in that: The housing contains an imaging objective lens positioned on the imaging optical path between the sample hole and the photographic hole; the camera lens, photographic hole, imaging objective lens, sample hole, and imaging optical path optical axis are all coaxially arranged, and the camera lens is located at the focal point of the imaging objective lens, so that the trace evidence located below the sample hole is imaged on the photosensitive element.

2. The trace evidence photographic device according to claim 1, characterized in that: The built-in camera device is located at the top of the housing, the camera aperture is located at the top of the housing, and the sample inspection aperture is located at the bottom of the housing.

3. The trace evidence photographic device according to claim 1, characterized in that: The trace evidence is imaged on the photosensitive element, and satisfies the following: the ratio of the optical imaging length of the trace evidence to the length of the trace evidence is equal to the ratio of the distance between the camera lens and the photosensitive element to the focal length of the imaging objective lens.

4. A trace evidence photographic device according to any one of claims 1 to 3, characterized in that: The imaging objective is located directly above the sample aperture, and the camera aperture is located directly above the imaging objective.

5. A trace evidence photographic device according to any one of claims 1 to 3, characterized in that: A reflective assembly is provided in the imaging optical path inside the housing. The reflective assembly includes a first reflector and a second reflector. The imaging objective lens is disposed in the imaging optical path between the first reflector and the second reflector. The first reflector is located directly above the inspection hole, and the second reflector is located directly below the photographic hole.

6. The trace evidence photographic device according to claim 5, characterized in that: The first reflector is at a 45° angle to the horizontal plane to reflect the optical axis of the imaging optical path that enters the housing through the inspection hole into the imaging objective lens in a horizontal direction; the second reflector is at a 135° angle to the horizontal plane to reflect the optical axis of the imaging optical path in a horizontal direction into the camera aperture.

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