Microscope without lenses.
In its nearly 300-year history of development, the microscope has become, perhaps, one of the most popular optical instruments widely used in all areas of human activity. It is especially difficult to overestimate its role in teaching schoolchildren who know the surrounding microcosm with their own eyes.
A distinctive feature of the proposed microscope is the "non-standard" use of a conventional Web-camera. The principle of operation consists in the direct registration of the projection of the objects under investigation onto the surface of the CCD matrix when illuminated by a parallel beam of light. The resulting image is displayed on the PC monitor.
Compared with a conventional microscope, the proposed design does not have an optical system consisting of lenses, and the resolution is determined by the pixel size of the CCD matrix and can reach microns . The appearance of the microscope is shown in Fig. 1 and fig. 2. As a Web-camera used model "Wcam 300A" company Mustek, which has a color CCD 640x480 pixel resolution. Electronic board with a CCD matrix (Fig.3) dismantled from the case and after a small revision installed in the center of the light-tight case with an opening lid. The revision of the board consisted in soldering the USB connector in order to provide the possibility of installing additional protective glass on the surface of the CCD array and sealing the board surface.
A through hole is made in the case cover, in the center of which there is a block of three LEDs of different colors of light (red, green, blue), which is a source of light. The block of LEDs, in turn, is closed by an opaque cover. The remote location of the LEDs from the matrix surface allows you to form an approximately parallel beam of light on the measurement object.
The CCD matrix is connected to the PC using a USB cable. The software is standard, supplied with the Web camera.
The microscope provides for image magnification by 50 ... 100 times, at an optical resolution of about 10 microns with a frequency of image refresh 15 Hz.
The design of the microscope is shown in Fig. 4 (without respecting the scale).
To the input window of the CCD of the matrix 7 to protect it from mechanical damage, a quartz protective glass 6 with dimensions of 1x15x15 mm. Protection of the electronic board from liquids and mechanical damage is provided by sealing its surface with silicone sealant 8. Test object 5 is placed on the surface of protective glass 6. Lighting LEDs 2 are installed in the center of the opening of the cover 4 and are covered outside with an opaque plastic casing 3. The distance between the object and the LED block is about 50 ... 60 mm.
The power of the lighting LEDs (Fig. 5) is supplied from a battery of 12 out of three connected in series 4.5 V galvanic cells. The power is turned on by the switch SA1, the HL1 LED (1 in Fig. 4) is indicator, located on the protective cover and signals the presence of supply voltage. The lighting of the EL1-EL3 LEDs is turned on, and thus the color of the lighting is selected using switches SA2-SA4 (13) located on the side wall of the housing 11.
Resistors R1, R3-R5 are current-limiting.Resistor R2 (14) is designed to adjust the brightness of the EL1-EL3 LEDs, it is installed on the back of the case. The device used fixed resistors C2-23, MLT, variable - SPO, SP4-1. Power switch SA1 - MT1, switches SA2 — SA4 - pushbutton SPA-101, SPA-102, AL307BM LED can be replaced with КИПД24А-К
Because the visible size of displayed images depend on the characteristics of the video card used and the size of the monitor, the microscope requires calibration. It consists in the registration of a test object (transparent school ruler), the dimensions of which are known (Fig. 6). Measuring the distance between the strokes of the ruler on the monitor screen and correlating them with the true size, you can determine the scale of the image (zoom). In this case, 1 mm of the monitor screen corresponds to 20 μm of the object being measured.
With the microscope, you can observe various phenomena and measure objects. In fig. 7 shows the image of laser perforation of a 500-ruble banknote. The average diameter of the holes - 100 microns, visible scatter holes in shape. In fig. 8 shows an image of a Hitachi color kinescope mask.The diameter of the holes is about 200 microns.
The spider, its foot and whiskers are selected as examples of biological objects; they are shown in fig. 9 and fig. 10, respectively (diameter of the barb is about 40 microns), the author's hair (diameter is 80 microns) - in fig. 11, fish scales - on rice. 12. It is interesting to observe the processes of dissolution of substances in water. As an example, shows the processes of dissolution of salt and sugar. In fig. 13, a and fig. 14a shows particles of dry salt and sugar crystals, respectively, and Fig. 13.6 and fig. 14.6 - the process of their dissolution in water. Clearly visible areas of increased concentration of substances and the effects of focusing light in the dissolution centers.
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