The gel imaging produced by each company is similar in structure, and can be used for non-chemiluminescence imaging such as DNA/RNA/ protein gel electrophoresis (such as EB , Coomassie blue, silver staining). Detection and analysis, mainly to distinguish the sensitivity and resolution of gel imaging, the quality of the image to be taken is mainly depends on the size of the CCD , pixels, and a software function of imaging.
The following is an introduction to CCD :
A: CCD is a Charge Coupled Device (Charge Coupled Device) acronym, which is a semiconductor imaging device, which has high sensitivity, anti-glare, distortion, small size, long life, resistance to vibration and so on.
( 1 ) CCD size and image quality
CCD size is a fixed target and the imaging performance impact force, is the length of a diagonal line of CCD, That is, the size of the CCD sensing device determines the size of the area means. The larger the area of ​​the photosensitive device, that is, the larger the CCD/CMOS area, the more photons are captured, the better the photographic performance, and the lower the signal-to-noise ratio. In the case of the same pixel, the larger the area of ​​the CCD , the larger the area of ​​a single photosensitive unit, and the stronger the signal-to-noise ratio and the photographic ability, the better the image quality. Conversely, the smaller the area of ​​a single photosensitive unit, the weaker its signal-to-noise ratio and sensitivity, and the quality of the image will be deviated.
( 2 ) Â CCD pixel
Usually, how many pixels are used to describe the performance of the camera . The pixel is understood to be the basic material of the image . In France, there is a painting called the point color , which is to point out millions of small oil color points on the canvas. The method of composing the paintings , when you stand at a certain distance to see the paintings of the dot paintings , these color points are mixed to form a seamless painting ; the digital image is the same as the principle of the point painting school , but instead of small the painting is one point called pixels (pixel) color small square.
There is no absolute relationship between the pixel level and the size. Generally, the intuitive idea is that the higher the pixel of the CCD , the more space it needs, and the larger the area size of the CCD should be! Compared with the current production technology, this concept is correct and not correct. In fact, the pixel area size and the fineness of the line layout are the key factors affecting the size of the CCD ; that is, the more precise the manufacturing technology, the smaller the space required for the line, and the relative pixel area can be fixed. Closer, it can achieve the purpose of further reducing the area, so in the case of a certain pixel area, the tighter the line layout, the higher the pixel, the larger the CCD size, the better the image quality.
Two: CCD structure decomposition upper layer is the brightness enhancement lens, the middle layer is the color separation filter, the lower layer is the photosensitive layer
The first layer of "enhanced lens"
We know that the key to digital camera imaging lies in its photosensitive layer. In order to expand the CCD 's luminous rate, it is necessary to extend the light receiving area of ​​a single pixel. However, the method of increasing the daylighting rate is also likely to degrade the image quality. This layer of "micro lens" is equivalent to adding a pair of glasses in front of the photosensitive layer. Therefore, the photosensitive area is no longer determined by the opening area of ​​the sensor, but is determined by the surface area of ​​the microlens.
The second layer is the "separation filter"
The second layer of the CCD is a "color separation filter". There are currently two color separation methods, one is the RGB primary color separation method, and the other is the CMYK complementary color separation method. First of all, let us first understand the concept of two color separation methods, RGB is the three primary color separation method, almost all the colors that human glasses can recognize, can be composed of red, green and blue, and the three letters of RGB are Red. Green and Blue , which means that the RGB color separation method is adjusted by the color of these three channels. Let's talk about CMYK , which is made up of the colors of four channels. They are cyan ( C ), magenta (M) , yellow (Y) , and black (K) . In the printing industry, CMYK is more suitable, but its adjusted color is not as much as RGB .
The advantage of the primary color CCD is that the picture quality is sharp and the color is real, but the disadvantage is the noise problem. Therefore, you can note that digital cameras that use primary color CCDs generally do not exceed 400 in ISO sensitivity. In contrast, the complementary color CCD has a Y yellow color filter, which is more careful in color resolution, but sacrifices the resolution of some images. In the ISO value, the complementary color CCD can tolerate higher sensitivity, generally Can be set above 800
Third layer: photosensitive layer
The third layer of the CCD is a "photosensitive sheet". This layer is mainly responsible for converting the light source that passes through the filter color layer into an electronic signal, and transmits the signal to the image processing chip to restore the image.
The traditional camera film size is 35mm , 35mm is the diagonal length, and the 35mm film has a photosensitive area of 36 x 24mm . Converted to a digital camera, the diagonal length is approximately 35mm , and the CCD/CMOS size is larger. SLR digital cameras, many have close to the 35mm of the CCD / CMOS size, for example Nikang De D100, CCD / CMOS size of an area of 23.7 x 15.6, compared to consumer digital cameras to be much larger, and the Canon EOS-1Ds of CMOS dimensions of 36 x 24mm, 35mm reached the area, so the image is relatively good.
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