What is the tunnel "black hole" phenomenon?

Driving through the tunnel, because suddenly from the bright place into the dark place, so people see the first tunnel is a black hole, from the tunnel when it is just the opposite, the human eye is a white hole, and can not see other things inside and outside the tunnel, this kind of phenomenon known as the "black hole" "white hole" phenomenon. When the driver enters the tunnel at high speed in the daytime, the driver can not adapt to the phenomenon of black hole. This is the result of sudden changes in the pupil of the eye.

Pupil plays an important role in the optical system of the eye. The pupil can not only respond to the light and shade, regulate the light entering the eye, but also affect the focal depth and spherical aberration of the optical system of the eye.

Adult pupil diameter is generally 2.5--4mm, positive circle, on both sides, etc.. Pupil size was related to age, gender, physical condition, external stimuli and emotion.

The variation range of the pupil can be very large, when extreme contraction, the pupil diameter is less than 1mm, and the extreme expansion, which is greater than 9mm, the iris sphincter can be reduced to 87% of its length, which is the body's other smooth muscle or striated muscle is almost impossible to achieve. Through the pupil adjustment, always maintain the proper amount of light entering the eye, which falls on the retina of the object image is clear, and there will be an excess of light burns the retina, but if the light entering the eye brightness changes too fast, it is difficult to adapt to the pupil.

The tunnel lighting design should consider this phenomenon, according to the actual situation inside and outside the tunnel illumination, at the entrance to the tunnel through the clever cloth lamp and lighting control, set the lighting transition zone, as far as possible to make the visual discomfort reduce tunnel import.