Redemption of light The existing visitation room is divided into two homogeneous parts, which are used by juvenile offenders and their families. It is separated by ordinary glass, and there is often no large area of natural lighting. The light environment usually use electric lighting, and the space atmosphere is cold. Two optical phenomena, “pinhole imaging”and“single slit diffraction”, are introduced in our reconstruction. The ordinary glass separated in the middle is changed into one-way glass, and slits are opened at the edge of the wall on one side of the juvenile offender. When the light is projected, the single slit diffraction strip spot will appear on the glass, forming the image of the cage. Several small holes are opened on the glass, through which the image of the family is formed on the wall of the juvenile offender's side, forming some fuzzy inverted images. The space of family members is spacious and has warm color light. The space of juvenile offenders is low temperature, narrow and dark. The obvious contrast between the cold and warm in the two spaces represents two completely different lives. The living environment of relatives is warm and soft, while the juvenile offenders are in a strict and cold living environment. These two kinds of optical phenomena give more spiritual atmosphere to the space, which makes the juvenile offenders know that their relatives are close to each other, but they can only see the image of their relatives' fuzzy inverted images between the light spots like a cage. This helpless restraint makes the juvenile offenders deeply reflect on their mistakes and complete self salvation. Juvenile prison Juvenile prison is a place for educating, saving and reforming juvenile offenders who have reached the age of 14 or 18. It is also one of the labor reform institutions in China. According to the characteristics of juvenile delinquents, under the condition of taking care of their growth and development, let them engage in light labor, adopt the methods of induction, care, encouragement and influence, carry out the comprehensive education of morality, intelligence, beauty and physique suitable for the psychological and physiological characteristics of juvenile delinquents, promote their ideological transformation, and transform them into new people beneficial to society as soon as possible; and create for their future enrollment and employment conditions. Through the transformation of the visitation room, an important space in the juvenile prison, starting with the two roles in this space, that is, the juvenile delinquents and the family members of the juvenile delinquents who come to visit the prison, the visitation room is given the connotation of divinity through light treatment, so as to achieve the purpose of spiritual salvation and redemption for the juvenile delinquents. Single slit diffraction Single slit diffraction is a phenomenon that light meets obstacles in the process of propagation, and light waves will continue to travel around the obstacles. If the wavelength is equal to or greater than the size of the slit, hole or obstacle, the diffraction phenomenon is most obvious. The same light intensity exists on the screen with the same angle, so the diffraction patterns on the screen are some parallel stripes, which are parallel to the slit. Pinhole imaging A plate with a small hole is used to cover between the wall and the object, and the reflection of the object will be formed on the wall. We call this phenomenon small hole imaging. Moving the middle plate back and forth, the size of the image on the wall will also change, which shows the nature of light propagation along a straight line. The closer the object distance is, the larger the image is and the darker the brightness is; the farther the object distance is, the smaller the image is and the brighter the brightness is. We regard the flame of candle as composed of many small luminous points, each of which emits light in all directions. There will always be a small beam of light, straight through the hole, forming a small spot on the white paper. Each light spot on the candle flame will form a corresponding light spot on the white paper, and all the light spots on the white paper will form a candle flame image. The light from the upper part of the candle flame shines on the lower part of the white paper through the small hole in a straight line; the light from the lower part of the candle flame shines on the upper part of the white paper through the small hole, so an inverted image is formed on the paper. This just shows that light travels in a straight line.