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What’s the usage of the filter on camera

Sep 23, 2017

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Filter function: 1. Filter infrared. 2. Trimming the incoming light

 

1, filter out infrared:

 

Color CCD can also sense the infrared, because it will be sensitive to infrared, will lead to DSP can not calculate the correct color, so need to add a filter, the infrared part of the light separated, so only the color CCD need to install filters, black and white It is not necessary.

 

2, trim the incoming light:

 

Because the CCD is a piece of photoreceptor (CELL) composition, the best light is direct in, but in order to interfere with the interference to the vicinity of the photoreceptor, you need to dress the light, so the filter is not glass, but quartz Film, the use of quartz physical polarizing characteristics, the incoming light, to retain the direct part of the reflection of the part of the oblique, to avoid the impact of the next side of the light.

 

Understand the basic functions, and talk about how to do it.


1 filter out infrared:

 

Can be coated with blue glass, the film is divided into vacuum coating and chemical coating, the chemical coating is the quartz film immersed in the solvent to be plated, low cost but the coating thickness is not easy and easy to fall off, vacuum coating is vacuum deposition method, coating uniform And is not easy to fall off, but the high cost of the above we call IR Coating, the purpose of filtering out the infrared, in addition to the so-called AR-coating coating, the purpose is to increase the light transmittance, because the light through the different media (such as From the air into the quartz sheet), will produce part of the refraction and reflection, coupled with AR-Coating, the filter can reach 98-99% penetration, or only 90-95 penetration, which CCD Sensitivity of course has an impact.

 

The other is the use of blue glass, blue glass is "absorption" way to filter infrared, and IR-Coating is the way to filter out the infrared light, but the reflected light is likely to cause interference, if only consider filtering out infrared, blue glass is better But the glass is not used to trim the light, so there is a piece of blue glass plus a piece of quartz film so-called "two-piece" filter which blue glass used to filter the infrared, and quartz film trim light, so quartz On-chip only need to do AR-Coating on the line.

 

2. Trimming into the light:

 

As mentioned above, the use of quartz's physical polarization characteristics, the incoming light, to retain the direct part of the reflection of the oblique part, but only one direction of dressing, usually only consider the horizontal resolution of the camera, so only the light to do The level of dressing, so the direction of the filter to the right, can not be reversed. That if the vertical light should be trimmed, then how to do? Very simple, stick to two pieces, one of which turned 90 degrees on the line, so there This is also called "two-piece" filter, one used in the horizontal dressing, one used in the vertical dressing, one of them do IR-Coating to filter the infrared.

That is more advanced? Is the two pieces of quartz middle clip blue glass, then there are advantages, this "three-piece common in Japan imported machine.

 

Said so much, or no concept, then, can be a small test, props is very simple --- a tie, but also fine and dense stripes will be the kind of light, a quartz because of the vertical Dressing, the camera according to it will produce a color of a flower interference, two-piece will not, if the striped tie no color interference but is a straight tie, haha! Filter posted against.

 

And we often see visitors on the TV, and some with twisted tattoo tie, the camera is also like a flower, not a camera rotten, one more than ten million! But the filter only two, only to Horizontal and vertical surface dressing, encountered 45 degrees angle of the twill no more, unless the addition of two on the left 45 degrees and 45 degrees to do the dressing, so that so many pieces of change on the cake. The host will never bring twill tie on the lens, you have the opportunity to have the opportunity to remember!

What is the function of the dual filter?

 

Now the camera has night vision function, this night view depends on what can be completely dark in the state to see the object? In order to filter the sun during the day when the infrared light produced in front of the CCD we posted the cut off the infrared light blue glass, and to the night the LED light, and then to the infrared light, Issued by the infrared light is also blue glass filter, can not be imaged, how to solve this contradiction? How to do in the day off the infrared light to make the image clear, true, at night can make LED infrared light completely into the CCD to complete the night vision function? This is the function of a dual filter, it is by a mechanical device to complete the day in front of the CCD cut off the infrared light filter, to the night automatically switch to a full transparent filter, so that meet the infrared night vision Camera requirements. This mechanism is called dual filter switch referred to as IR-CUT. Currently on the market can be done during the day double crystal folder blue glass, the night three crystal seems to only Shenzhen Witt letter technology company a switch, model ICR-V02M1. If you are interested can find the Internet, they can provide samples to the camera factory test results.

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