Novel optical experiment system

Abstract

The invention discloses a novel optical experiment system. According to the structure, a light source, an object screen, a lens and an image screen are sequentially installed on the upper portion of an optical bench through slidable supports from left to right. A photoelectric sensor is further installed on the image screen and connected with an electricity meter, and the light source is connected with a power source. And a detachable light shield is arranged outside the image screen. The front face of the light shield is provided with a vertical strip-shaped hole and an observation window, small magnetic steel is installed on the inner side of the periphery of the opening edge of the strip-shaped hole, the two movable light shielding pieces are attracted to the strip-shaped hole of the light shield through magnetic force, and the size of a light inlet opening can be adjusted. According to the utility model, the intensity of an electric signal output by a photoelectric sensor is used for replacing the judgment of human eyes on the focusing condition, so that the measurement error caused by insensitivity and inaccuracy of judging the focusing condition by the eyes in the prior art is overcome, the precision of measuring the focal length of the lens is improved, the experimental error is obviously reduced, and the influence of ambient light is reduced. The device is used for college physics experiment teaching.

Description

Technical Field

[0001] The invention relates to a university physics experiment device, in particular to a new optical experiment system. Background Art

[0002] Using an optical bench and an optical device to form an optical experimental system to conduct experimental projects such as measuring the focal length of a lens is a common content of university physics experiments. Among them, the lens focal length measurement experiment is used to measure the focal length of a thin convex lens or a concave lens. When doing the experiment, place the light source, object screen, lens (one or two), and image screen (or white screen) on the optical bench from left to right. The measurement methods include object distance to image distance method, two-time imaging method, and self-collimation method. These experimental methods all require adjusting the position of the lens or object screen or image screen so that the clarity of the image formed on the image screen (or white screen) is optimal, and then read out the position coordinates of each component on the optical bench, so as to obtain the object distance, image distance and other dimensional data, and substitute them into the formula to calculate the focal length of the lens. However, when doing experiments, it is often found that the position of the convex lens, object screen or image screen is moved up to 0.5 cm or more, and there is no obvious change in the clarity of the image. In other words, it is impossible to accurately adjust the position of each component by eye observation to achieve the best focus, which leads to large errors in the object distance, image distance and other dimensions, and ultimately the calculated focal length of the lens is also very large. In addition, the ambient light during the experimental operation reduces the contrast of the image formed on the image screen, making the eye insensitive to observation, and objectively reducing the clarity of the image on the image screen. Summary of the invention

[0003] The purpose of the present invention is to provide a new optical experimental system which can reduce the influence of ambient light and can be adjusted to an accurate focusing state, so as to accurately measure various dimensions required for calculating the focal length of the lens, such as the object distance and the image distance, and further accurately calculate the focal length of the lens.

[0004] In order to achieve the above purpose, the present invention installs a light source 2 above the end area of ​​the optical bench 1, an object screen 4 is installed on the upper part of the optical bench 1 through an object screen slidable bracket 11, a lens 5 is installed on the upper part of the optical bench 1 through a lens slidable bracket 12, an image screen 6 is installed on the upper part of the optical bench 1 through an image screen slidable bracket 13, and the light source 2 is connected to the power source 3 through a double-strand power line. A photoelectric sensor 7 (photodiode or solar cell panel) is installed on the image screen 6, and the photoelectric sensor 7 is connected to an electric meter 8 (various types of electric meters such as a voltmeter or an optical power meter) through a multi-core wire.

[0005] In order to reduce the influence of ambient light on the experiment, improve the measurement accuracy of the photoelectric sensor 7 and the contrast and clarity of the image observed by the human eye, a detachable light shield 9 is also installed on the outside of the image screen 6. The light shield 9 has a movable light shielding sheet 16 and an observation window 17. A vertical strip opening 14 is opened in the central area on the left side of the refracting cover 9. Some small magnetic steels 15 are installed on the inner side around the opening edge of the strip opening 14. Four movable light shielding sheets 16 are magnetically adsorbed on the strip opening 14 of the refracting cover 9, and the size of the opening for light entry can be adjusted. The refracting cover 9 also has an observation window 17, which is used to observe the imaging situation on the image screen 6.

[0006] Since the present invention installs the photoelectric sensor 7 on the image screen 6, when the imaging is in the best state, the imaging light intensity is also the highest, and the voltage output by the photoelectric sensor 7 is also the highest. The light intensity voltage is sent to the electric meter 8 through the multi-core wire, and then the highest light intensity voltage (or light power) is displayed. At this time, the various dimensions such as the object distance and the image distance measured are much more accurate than when the human eye observes the focusing (experiments show that the human eye observes the focusing to move the optical components 5 mm or more, and the effect on the clarity of the imaging is not significant and basically cannot be seen), thereby achieving the purpose of high-precision measurement of the focal length of the lens. The present invention uses the intensity of the sensitive and quantitative photoelectric sensor output electrical signal to replace the human eye's judgment on the quality of focusing, overcomes the measurement error caused by the insensitivity and inaccuracy of the human eye in judging the quality of focusing in the prior art, improves the accuracy of lens focal length measurement, and significantly reduces experimental errors.

[0007] In the prior art, the ambient light has a great influence on the experimental light, resulting in poor contrast of the image and unclear images observed by the human eye. However, the present invention installs a detachable light shielding cover 9 on the outside of the image screen 6, which significantly improves the clarity of the image and the light intensity detection sensitivity of the photoelectric sensor 7, further improves the accuracy of measuring various dimensions such as object distance and image distance, and achieves the effect of further improving the measurement accuracy.

[0008] Moreover, the present invention not only adopts advanced high-sensitivity photoelectric sensors in conjunction with electric meters to quantitatively detect the quality of focusing data, but also retains the traditional method of observing with the human eye and manually adjusting the imaging clarity, with the aim of deepening students' understanding of experimental phenomena; the added light shield makes the focusing and observation clarity effect more obvious, deepening students' perception of the lens imaging clarity. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0010] Figure 2 It is a structural diagram of the light shield of the present invention. DETAILED DESCRIPTION

[0011] See also Figure 1. The optical bench 1 can use various structures of optical benches in the prior art. A scale is installed on the optical bench 1 for reading the positions of various optical components on the optical bench 1, so as to calculate various sizes required for the experiment. The length of the optical bench 1 is 0.6-1.2 meters. A light source 2 is installed at one end (such as the left end) of the optical bench. The light source 2 can be a tungsten filament lamp or other types of light sources. The light source 2 is connected to the output end of the power supply 3 through a double-strand wire. The power supply 3 can be a low-voltage power supply using AC mains power, or it can be a battery, as long as it matches the rated voltage of the light source 2. On the right side of the light source 2 is the object screen 4, which is plugged into the object screen sliding bracket 11 and fixed to each other by screws, and then the object screen sliding bracket 11 is installed on the upper part of the optical bench 1. The object screen 4 is a metal sheet with a hole in the shape of a letter "1" (or other patterns) in the center, so that the light emitted by the light source 2 can pass through the object screen 4 and then pass through the lens to form an image in the shape of a letter "1" on the image screen 6. The image in the shape of a letter "1" formed on the image screen 6 can be seen inverted and flipped left and right, that is, the object screen 4 is equivalent to an "object" formed by a lens, and the distance between the object screen 4 and the lens 5 is the object distance. The lens 5 is located on the right side of the object screen 4. The lens 5 is plugged into the lens slidable bracket 12 and fixed to each other by screws, and then the lens slidable bracket 12 is installed on the upper part of the optical bench 1. When it is necessary to measure the focal length of a convex lens, the lens 5 is a convex lens; when it is necessary to measure the focal length of a concave lens, the lens 5 is composed of two different types of lenses, a convex lens on the left and a concave lens on the right, that is, at this time, the lens 5 includes a convex lens and a concave lens. The image screen 6 is on the right side of the lens 5, and the image screen 6 is installed on the upper part of the optical bench 1 through the image screen slidable bracket 13.

[0012] A photoelectric sensor 7 (photodiode or solar panel) is also installed on the image screen 6. The installation method is to drill a small hole with a diameter of 2-5 mm in the center of the image screen 6, and then install the photoelectric sensor 7 on the back (i.e., right) of the image screen 6 by fasteners such as screws. Then, when doing the experiment, it is necessary to adjust one of the light source 2, the object screen 4, the lens 5, and the image screen 6 to adjust the image formed on the image screen 6 to move to the position of the small hole, so that the imaging light falls on the photoelectric sensor 7 and the light intensity of the image can be detected. The photoelectric sensor 7 is connected to the electric meter 8 through a multi-core wire. In this way, when the relevant optical components are adjusted to make the imaging focus on the image screen 6 optimal, the output voltage of the photoelectric sensor 7 is also the highest, and the voltage value (or optical power value) displayed by the electric meter 8 is also the highest, which is much more accurate than the human eye observing the imaging clarity. In actual operation, it is found that the lens 5 (or the moving object screen 4 and other components) have moved more than 5 mm, and the change in imaging clarity cannot be seen. The object distance, image distance and other dimensions measured at this time are much more accurate than when the human eye observes the focus, thereby achieving the purpose of high-precision measurement of the focal length of the lens. The present invention uses a sensitive and quantitative photoelectric sensor output electrical signal intensity display to replace the human eye's judgment of the focus, overcoming the measurement error caused by the insensitivity and inaccuracy of the human eye in judging the focus in the prior art, improving the accuracy of lens focal length measurement and significantly reducing experimental errors.

[0013] The electric meter 8 can be any type of electric meter such as a high input impedance, high sensitivity DC voltmeter or optical power meter in the prior art. It is best to use a digital electric meter with a multi-range switching function or a large number of display digits and automatic switching of the decimal point position to improve the detection sensitivity.

[0014] In order to further improve the sensitivity of light intensity detection, the following two measures can be taken: first, the photoelectric sensor in the prior art is integrated with the front-stage DC amplifier to avoid the interference caused by the long lead and improve the photoelectric detection sensitivity; second, the photomultiplier tube device dedicated to detecting extremely weak light signals in the prior art is installed in the present invention, then the photoelectric sensor 7 is the photomultiplier tube, and the light inlet of the photomultiplier tube should be installed at Figure 1 The photoelectric sensor 7 is located in the middle. The photomultiplier tube and the subsequent amplification and digital display circuit can be used in the prior art, and the subsequent amplification and digital display circuit is equivalent to the electric meter 8. If a photomultiplier tube detection device is used, the photoelectric detection sensitivity can be improved by several orders of magnitude, which is most significant for improving the accurate focusing effect of this experimental device, because the photomultiplier tube itself has a low-noise amplification effect of photoelectric conversion.

[0015] The light source 2 is connected to the power source 3 through a double-strand power line. The power source 3 can be a low-voltage direct current or alternating current obtained by stepping down and rectifying the 220V AC mains, or it can be replaced by batteries installed in a battery box, as long as the output voltage of the power source 3 matches the supply voltage of the light source 2. The light source 2 can be installed on the optical bench 1 in a fixed manner, or it can be installed in an installation mode using the above-mentioned slidable brackets (such as the object screen slidable bracket 11), where the light source 2 is installed on the light source slidable bracket, and the light source slidable bracket is installed on the optical bench 1. In this way, the light source 2 can also be manually adjusted and slidable on the optical bench 1 like the object screen 4, the lens 5, and the image screen 6. This makes it easy to focus the image by adjusting the position of the light source 2, and the experimental method is more diversified.

[0016] In order to reduce the influence of ambient light on the experimental light, improve the measurement accuracy of the photoelectric sensor 7 and the contrast clarity of the image observed by the human eye, a detachable light shielding cover 9 is also installed outside the image screen 6. Figure 2 The refraction hood 9 is a square box made of iron sheet (it can also be made of hard plastic), and its bottom has a bottom opening 18. The size of the bottom opening 18 is such that the image screen 6 can be inserted into the interior of the light shield 9 and the smaller the opening area, the better (in order to reduce light leakage). In this way, the light shield 9 can be placed outside the photoelectric sensor 7 and can also be taken upward. At the four corners of the bottom of the light shield 9, four adjustable height legs 19 can be vertically installed (four long screws can be used to vertically install near its four legs), a total of four, and the bottom of the legs 19 falls on the experimental table to stabilize the position of the light shield. The legs 19 can be either fixed in length or adjustable in length (for example, four long screws are used to screw on the four threaded round holes at the bottom of the light shield 9 with a threaded structure). The length of the legs 19 is preferably to support the light shield 9 so that the image screen 6 is located in the middle of the light shield 9 in the vertical direction.

[0017] A vertical strip opening 14 is opened in the central area of ​​the left side (front) of the refracting cover 9, which is about 7 cm long and 2 cm wide. On the inner side of the opening edge of the strip opening 14, a number of small magnets 15 are glued with AB double-tube glue (2-5 magnets are glued to each side), and then two identical movable shading sheets 16 are made of iron sheets for vertical use, each of which is slightly larger than the strip opening 14 (8 cm long and 4 cm wide). These two vertical movable shading sheets 16 are movably attracted to the strip opening 14 by magnetic force. Two square movable shading sheets 16 with a length and width of 3 cm are made for horizontal use (it can be stacked on the vertical shading sheet by magnetic force, but in order to avoid Figure 2By adjusting the positions of the four movable light shielding sheets 16 on the strip opening 14, the size and position of the light-inlet hole can be adjusted at will to meet the requirements of the thickness and position of the incoming light beam under different experimental conditions, and to adapt to light beams of different diameters and different positions to fully enter the light shield 9 with minimal light leakage. The thickness of all the above-mentioned iron sheet materials is about 0.3 mm.

[0018] The refracting cover 9 also has an observation window 17 for observing the clarity of the image. The observation window 17 can be formed by opening a circular hole with a diameter of about 2 cm in the edge area of ​​the front side of the refracting cover 9. When the eyes are close to the observation window 9 to observe the image of the internal image screen 6, the ambient light entering and affecting the clarity of observation can be reduced. The observation window 17 can also be opened into a large square opening, and also equipped with a structure with an adjustable opening area similar to the strip opening 14 and the movable light shielding sheet 16. When the opening is adjusted to a small size, it is necessary to use the eyes to look at the opening, and when the opening is adjusted to a large size, it is not necessary to look at the opening, and observation from a distance is also possible, but the influence of ambient light is significantly greater than the former.

[0019] There is no special requirement for the volume size of the light shield 9. In principle, it only needs to be slightly larger than the area of ​​the image screen 6 and have a longitudinal dimension of 5-8 cm (this is to facilitate the use of the eyes to see the image formed on the object screen 6 through the observation window 17. If the longitudinal dimension is too small, it will not be visible).

[0020] It can be seen that this embodiment not only adopts advanced photoelectric sensors in conjunction with electric meters to quantitatively detect the quality of focusing data with high sensitivity, but also retains the traditional method of observing with the human eye and manually adjusting the imaging clarity, with the aim of deepening students' understanding of the experimental phenomena; the added light shield makes the focusing and observation clarity effect more obvious, deepening students' perception of the lens imaging clarity.

[0021] The experimental method of the present invention (taking the measurement of the focal length of a convex lens as an example) is as follows: Figure 1 After installing all the optical components (it is optional to not install the light shield 9 first), adjust the position of one or more of the optical components, such as the light source 2, the object screen 4, the lens 5, and the image screen 6, on the optical bench 1, so that the object screen 4 can present an inverted and relatively clear image in the central area of ​​the image screen 6, then buckle the light shield 9 on the image screen 6, and adjust the gap between the upper and lower movable light shielding sheets 16 to be slightly larger than the light beam from the object screen (as long as the light beam does not hit the movable light shielding sheets 16), at this time, the complete image on the image screen 6 can be seen through the observation window 17. Then carefully adjust the above-mentioned optical components to maximize the reading of the electric meter 8 (at this time, the image presented on the image screen 6 is also clearer than before), record the position of each optical component on the optical bench 1, and thus calculate the object distance and image distance, and use the focal length calculation formula of the convex lens to calculate the focal length of the lens.

Claims

1. A novel optical experimental system, wherein a light source (2) is installed above the end area of ​​an optical bench (1), an object screen (4) is installed on the upper part of the optical bench (1) through an object screen slidable bracket (11), a lens (5) is installed on the upper part of the optical bench (1) through a lens slidable bracket (12), an image screen (6) is installed on the upper part of the optical bench (1) through an image screen slidable bracket (13), and the light source (2) is connected to a power source (3) through a double-strand power line, wherein the light source (2) is connected to a power source (3) through a double-strand power line, wherein the light source (2) is connected to a power source (3) through a double-strand power line, and the light source (2) is connected to a power source (3) through a double-strand power line, and the light source (2) is connected to a power source (3) through a double-strand power line, and the light source (2) is connected to a power source (3) through a double-strand power line, and the light source (2) is connected to a power source (3) through a double-strand power line, and the light source (2) is connected to a power source (3) through a double-strand power line, and the light source (2) is connected to the ... A photoelectric sensor (7) is also installed on the image screen (6), and the photoelectric sensor (7) is connected to the electric meter (8) via a multi-core wire. A detachable light shield (9) is also installed outside the image screen (6).

2. The novel optical experimental system according to claim 1 is characterized in that The detachable shading cover (9) is provided with a movable shading sheet (16) and an observation window (17). A vertical strip opening (14) is opened in the central area on the left side of the refracting cover (9). Some small magnetic steels (15) are installed on the inner side around the opening edge of the strip opening (14). Two movable shading sheets (16) are magnetically adsorbed on the strip opening (14) of the shading cover (9). The refracting cover (9) also has an observation window (17).

3. The novel optical experimental system according to claim 1 is characterized in that The photoelectric sensor (7) is integrated with the front-stage DC amplifier.

4. The novel optical experiment system according to claim 1 is characterized in that The photoelectric sensor (7) is a photomultiplier tube.

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