Optical devices

Optical devices help us to explore our world. The telescope can detect and examine the outlines and details of distant cosmic bodies, and the microscope reveals the secrets of our planet, for example, the structure of living cells.
Our eyes. in fact, are optical devices. When we look at an object, a lens system located in front of each eye, forms its image on the retina - the layer of the fundus of the eye contains about 125 million light-sensitive cells. Light falling on the retina causes the cells to send to the marrow of electrical nerve signals, enabling us to visually perceive the object.
In addition, the eyes have a brightness control system. In bright sunlight the pupil instinctively narrowed, reducing the image brightness to an acceptable level. In the case of low light the pupil dilates, increasing the brightness of the image.