什么 exactly is a 640 x 480 红外线 camera? This can be a complicated answer for many reasons. In the following 文章 we will attempt to address some of the characteristics that can make this seemingly simple question so complicated. Specifically, we will briefly discuss 红外线 technology and the reference to display resolution and how they relate to a 640 x 480 红外线 camera.
首先让我们讨论一下“infrared” when we talk about a 640 x 480 红外线 camera. The term “infrared” refers to the 电磁辐射的波长. The wavelength of 红外线 radiation generally ranges between 0.7 and 300 micrometers abbreviated as “µm.”定义的确切范围和类别可能会略有不同，具体取决于用于描述辐射的比例。
就我们的目的而言，足以知道红外辐射的波长比可见光的波长长，因此人眼看不到它。此外，基于波长可能有几种红外辐射，但我们将仅考虑两种。“near 红外线”人眼看不见的辐射，但波长与人眼可见的辐射最接近的辐射）和“long-wavelength” also called “far 红外线,”我们讨论的是热成像区域，它是物体自然发出的，不需要外部或人工照明。
So, on this basis there are essentially two types of 640 x 480 红外线 cameras. The first type, and the one most commonly used in digital video 安全监控系统s, is the 近红外 camera. This camera contains one of two electronic sensor chips, either a Charged Coupled Device (CCD) or a Complimentary Metal Oxide Semiconductor (CMOS). These sensors are able to convert the light energy into electrical energy that can be measured, thereby creating a digital image. Fortuitously, these sensors inherently detect 近红外 radiation as well.
The 近红外 640 x 480 camera uses external 红外线 radiation (or 红外线 light) to illuminate the area in its field of view. These cameras use InfraRed Light Emitting Diodes or 红外 LEDS to illuminate the target area in order to create an image. The 红外灯 are normally configured in an array that surrounds the camera lens so that they are focused in the same direction. However, some cameras may have 红外灯 clustered off to the side of the lens and there are even separate “illuminators”除了红外LED外，没有任何其他东西，可以与相机分开安装和对准它们。
These cameras normally produce a color image in 可见光条件 and when the visible light is not bright enough to produce a 高质量的视频图像, they switch to 红外线, producing a 单色 or black and white video image.
远红外640 x 480红外热像仪不需要额外的外部红外照明。本相机使用红外线“Focal Plane Array”或FPA传感器，并且能够仅基于热辐射或“heat signatures”对象。这些相机通常被称为“前视红外”或FLIR相机。这些相机通常也是用“hand held”版。这些相机的旧型号必须以某种方式冷却以防止用户’以及由于干扰图像而产生的自身热辐射。
Far 红外线 640 x 480 红外线 cameras are often used not only for covert 监视 and security, but by 检查员和工程师 to detect a variety of 热签名. These cameras can be used to detect areas of heat “leakage” from a building or “hot spots”在机械发动机和其他设备上。
至于参考“640 x 480” in a 640 x 480 红外线 camera, this refers to the image resolution in pixels that the camera is capable of displaying. Far 红外线 cameras are more commonly referred to by their resolution in pixels, i.e. 640 x 480 红外线 camera. However, digital video 监视器s may also use the same description.
Perhaps the easiest way to tell the difference between the two is the price. Near 红外线 digital image security video cameras can be purchased for as low as less than one hundered while far 红外线 FLIR相机 range from one to several thousand dollars.