It is important that image quality is maintained as much as possible when using intensifiers. At the same time, light efficiency should be maximized. This can be achieved by using a fiber-optic window as the output of the first stage and as the input of the second stage.
A fiber-optic window is a solid piece of glass consisting of millions of parallel glass fibers sealed together. Each fiber acts as an independent light conductor. The shape of the window can either be flat (parallel input and output faces), or concave. Fibers with a concave surface are used for distortion correction in electrostatic image inverters.
Often the second stage will also have a fiber-optic output to allow coupling to a third stage, or to the image sensor of the camera. In the latter case the image sensor of the camera should be equipped with a fiber optic input window. In addition, take the following into consideration when you need to make a choice for either fiber-optic coupling or lens coupling:
- Fiber-optic coupling is a permanent connection; the connection is made during the manufacture of the integrated intensified camera.
- A fiber-optic window transfers an image from one face to the other. If the fiber optic has a tapered form, the image is reduced or enlarged. This characteristic can be used to match it to the format of a coupled imaging component.
- While fiber-optic coupling between intensifiers is the standard technique, coupling to the camera can also be done by lens optics. Disadvantages of lens coupling are the greater loss in efficiency (compared to fiber optics) and the lenses are more bulky.
- Lens coupling offers the flexibility of easy decoupling, allowing you a choice to make camera recordings with or without the use of an intensifier.