选择正确的照明.docVIP

Choose the Correct Illumination Often, a customer struggles with contrast and resolution problems in an imaging system, while underestimating the power of proper?illumination. In fact, desired image quality can typically be met by improving a systems illumination rather than investing in higher resolution detectors, imaging lenses, and software. System integrators should remember that proper light intensity in the final image is directly dependent upon component selection. Correct illumination is critical to an image system and improper illumination can cause a variety of image problems. Blooming or hot spots, for example, can hide important image information, as can shadowing. In addition, shadowing can also cause false edge calculations when measuring, resulting in inaccurate measurements. Poor illumination can also result in a low signal-to-noise ratio. Non-uniform lighting, in particular, can harm signal-to-noise ratios and make tasks such as thresholding more difficult. These are only a few of the reasons why correct illumination for your application is so important. The pitfalls of improper illumination are clear, but how are they avoided? To ensure optimal?illumination?when integrating a system, it is important to recognize the role that choosing the right components plays. Every component affects the amount of light incident on the sensor and, therefore, the systems image quality. The imaging lens aperture (f/#) impacts the amount of light incident on the camera. Illumination should be increased as the lens aperture is closed (i.e. higher f/#). High power lenses usually require more illumination, as smaller areas viewed reflect less light back into the lens. The cameras minimum sensitivity is also important in determining the minimum amount of light required in the system. In addition, camera settings such as gain, shutter speed, etc., affect the sensors sensitivity. Fiber optic illumination usually involves an illuminator and light guide, each of which shou