Hall 1 MAGICAL OPTICS

Introduction to the Hall

Welcome to the hall of MAGICAL OPTICS. This hall covers 660 square meters, with cyan as the main color, symbolizing the freshness and marvels of optical phenomena. It features four themed areas: the basic laws of light propagation, the colors of light, the principles of image formation, and the sensitivity of the human eye. Let’s step together into the fascinating world of light!

Funhouse Mirrors

The first exhibit you see is the Funhouse Mirrors. As you know, a flat mirror reflects an image in its true size. But when the surface is curved, optical principles cause distortions—this is the idea behind funhouse mirrors. The four mirrors on the outer side are shaped differently: convex horizontally, convex vertically, concave horizontally, and concave vertically—each producing unique distortions. The four mirrors on the inner side are more special: made of flexible materials, their curvature changes continuously under internal mechanical forces, so the reflections also shift continuously, creating an even more magical experience.

Light and Shadow in Nature

Welcome to Light and Shadow in Nature. The natural world is full of amazing optical phenomena: rainbows after a storm, mirages over seas or deserts, and the aurora borealis, to name a few. Here in the dome theater, you can explore and experience these wonders of light in nature.

The See-Through Wall

This is the See-Through Wall. The wall itself is opaque, yet we can still see the scene on the other side. Why is that? Take a look at the panel on the right: the “see-through wall” is actually made of flat mirrors arranged at specific angles. After four reflections, the light enters your eyes, allowing you to see what’s behind the wall.

Kaleidoscope

Here you see the Kaleidoscope. The beautiful, ever-changing patterns you observe inside are created by three flat mirrors facing inward. Objects form images within these mirrors, and each image is reflected again in the other two mirrors. This process repeats over and over, producing what appears to be an infinite number of images in this confined space.

The Floating Person

This exhibit is called The Floating Person. Please stand on the yellow footprints, lift one leg, and look at yourself in the mirror. Pay attention—which mirror are you looking into with that lifted leg? Do you look like you’re floating? Two flat mirrors are placed at a 90° angle. The image formed in one mirror appears as a symmetrical image in the other, making it seem as though you are “floating,” when in fact you’re just seeing the same leg reflected twice.

Corner of Optical Knowledge

Light is everywhere in nature, essential for plants, animals, and human daily life. Sunlight provides Earth with an endless source of energy. At the Corner of Optical Knowledge, you can explore more fun facts and insights about light.

Light and Shadow Sculpture

Welcome to the Light and Shadow Sculpture. When light encounters an obstacle in its path, a dark area—what we call a shadow—forms on the receiving surface. If the obstacle is made of translucent, colored material, the shadow will take on a corresponding color. By designing obstacles of different shapes and colors, people can create a dazzling world of light and shadow. Adjusting the distance and angle between the light source, the object, and the screen will change the size and position of the shadow. Press the button to try it yourself!

Workshop of Seven Colors

This is the Workshop of Seven Colors. Sunlight is a kind of mixed light. When a prism is used, it refracts different wavelengths at different angles, separating the light into its component colors. Rotate the prism to a certain angle, and you will see a band of seven colors—red, orange, yellow, green, cyan, blue, and violet—appear on the whiteboard.

If light can be dispersed, can it also be combined? The answer is yes. Red, green, and blue are called the three primary colors of light. By mixing them in different proportions, we can create virtually any color we want.

Light is both an electromagnetic wave and a stream of energy-carrying particles. In mixed light, photons of many kinds travel in different directions and phases, so the energy is relatively low. In contrast, laser light consists of a single type of photon, all moving in the same direction and in sync, which gives it extremely high energy. This is why laser beams must never be directed into the eyes. Since laser is monochromatic, it cannot be dispersed by a prism. Feel free to rotate the prism on the table and test it yourself!

The Mystery of the Eye

This exhibit is called The Mystery of the Eye. Known as “the window to the soul,” the eye is the most important of our sensory organs—about 87% of the knowledge and memories in the brain are acquired through vision. Our eyes can distinguish different colors and levels of light, converting these visual impressions into nerve signals that are sent to the brain. Because vision is so crucial, everyone should have an eye exam every one to two years. Through the information panels and eye models here, you can learn more about how the human eye works.

Water World of Light

This exhibit is called Water World of Light. It is composed of four parts: Light Changes with Water, Reverse Water Flow, Refraction of Light, and Guiding Light with Water Flow. Together, they demonstrate scientific principles such as reflection, refraction, and the stroboscopic effect through the clever combination of water and light.

On the far left is Light Changes with Water. When the arrow behind the water column passes through the water, refraction causes the direction of the arrow to appear reversed—an illustration of the principle of light refraction.

The middle part also demonstrates refraction. When a cylinder is immersed in water, it seems to vanish. But once it is lifted out, it reappears. Why? This is because the refractive index of the cylinder differs from that of air, so light bends at the cylinder’s surface, allowing us to perceive its edges. However, the refractive index of the cylinder is the same as that of water, meaning no bending occurs at the surface, no edge is perceived—and thus, the cylinder seems invisible.

On the right, you’ll see Guiding Light with Water Flow. Here, it looks as though the beam of light bends with the stream of water. In fact, light always travels in straight lines. What happens is total internal reflection at the boundary between the water and the air, which repeatedly reflects the light back into the stream. After many such reflections, the light appears to “follow” the water’s path.

At the top is Reverse Water Flow. In reality, gravity only allows water to flow downward. So why does it look like the water is flowing upward? This is an optical illusion caused by the stroboscopic effect and persistence of vision. Water droplets fall at regular intervals, leaving gaps between them. If the frequency of the strobe light is timed so that the interval between two flashes matches the interval between falling droplets, the droplets appear stationary. If the strobe interval is slightly shorter than the droplet interval, the droplets seem to flow upward—creating the illusion of reverse flow.

Glowing Gases

This exhibit is Glowing Gases. At night, city streets come alive with the colorful glow of neon lights. Tubes filled with different inert gases emit different colors when an electric current passes through them. Press the button to see for yourself. Do you know why each gas glows with a different color? The answer lies in the energy-level structures of gas molecules. Keep this question in mind—you’ll find the explanation in the Exploring Light gallery, where the theory of energy-level transitions is introduced.

Spinning Wheel

This exhibit is called Spinning Wheel. You may have noticed this phenomenon: when a car drives forward at night, its wheels sometimes appear to be turning backward. Why does this happen? It is an optical illusion caused by the stroboscopic effect and persistence of vision. In this exhibit, the light source has a fixed strobe frequency. By adjusting the wheel’s rotation speed, you can observe three different effects: the wheel appearing “stationary,” “rotating backward,” or “rotating forward.” When the time interval between two flashes of the strobe light matches the time, it takes for the wheel to complete one full turn, the wheel looks motionless. When the intervals don’t match, the wheel seems to rotate forward or backward. Press the “Start” button, turn the handwheel, and see the illusion for yourself.

Radiant Rose Garden

This is the Radiant Rose Garden exhibit. Red, green, and blue are the three primary colors of light, and by mixing them in different proportions, an endless variety of colors can be produced. In this rose garden, roses of different colors change their appearance under lights of different colors, vividly demonstrating the phenomenon of color mixing. Press the button and enjoy the magical effect of light blending.

Changing Faces

This exhibit is called Changing Faces. You’ll see two sets of masks—one pair in blue and green, and another in red and orange. When you press the button, the background panels on both sides slide over the masks, transforming them into blue and green, or red and yellow-orange. This happens because of color mixing. When two colors overlap, they form intermediate colors: blue-green mixed with violet dots appears blue, while blue-green mixed with yellow dots appears green; similarly, red-orange with violet appears red, and red-orange with yellow appears yellow-orange.

But why were yellow and violet chosen for the background panels? Because they are complementary colors. Yellow enhances violet, and violet makes yellow appear more vivid. This visual compensation effect is not only used in this exhibit but also in daily life. For example, surgeons wear blue-green clothing instead of white in operating rooms. This reduces eye strain caused by long hours under bright lights and lessens discomfort by making bloodstains appear dark brown rather than bright red.

Rainbow Pinwheel

This is the Rainbow Pinwheel exhibit. We live in a colorful world, and many of these colors arise from the phenomenon of light polarization—one of the defining characteristics that distinguishes transverse waves, like light, from longitudinal waves. Polarized light is everywhere: in the reflections off computer and phone screens, on water surfaces, or on polished floors and furniture. When a polarizing filter is placed in front of a white screen emitting polarized light, the filter selectively blocks or transmits the light depending on its polarization direction. When plastic or transparent tape is stretched, it becomes anisotropic and alters the polarization direction of the transmitted light. This selective absorption and transmission creates beautiful colored patterns—producing the rainbow-like effect you see in this pinwheel.

Holographic 3D Photography

This exhibit is Holographic 3D Photography. Holography involves two steps: recording and reconstruction. In the recording process, a laser beam is split into two parts. One beam shines directly onto the holographic plate, called the reference beam. The other beam illuminates the object, and the object’s reflected light falls onto the plate—this is the object beam. The object beam, carrying the information of the object, overlaps coherently with the reference beam on the holographic plate, creating an interference pattern that forms a hologram. In the reconstruction process, the hologram is illuminated with laser light of the same wavelength. Through diffraction, a three-dimensional image of the original object reappears in space. Since every point of the hologram records information about the entire object, even if part of the hologram is damaged, the image can still be reconstructed. This makes holography especially valuable for preserving and archiving precious artworks. The holographic 3D photographs you see here are produced by recording reconstructed 3D images onto a medium, making them viewable to the naked eye under white light.

Lenticular 3D Pictures

This is a Lenticular 3D Picture. It combines digital technology with printing techniques, layering multiple images beneath a surface covered with a lenticular lens sheet. The lenticular sheet is made up of an array of cylindrical lenses, which direct light from different parts of the image into the viewer’s eyes depending on the angle of observation. From different viewing angles, you’ll see different images. Because each of your eyes receives the image from a slightly different perspective, a parallax effect occurs—this difference between the two eyes’ views allows the brain to perceive a true 3D image.

Digital Holographic Plate

This exhibit is the Digital Holographic Plate. A 3D image is created by recording interference fringes formed by two coherent light beams. The digital holographic plate is composed of hundreds of thousands of pixels, each repeating the same recording process. Together, they form the complete holographic plate. During reconstruction, the plate is illuminated from nearly the same direction as the original reference beam, and diffraction reproduces the 3D image. Holographic imaging has a wide range of applications—from rendering realistic 3D terrains in military operations, to urban panoramic mapping, architectural design presentations, etc.

Little Scouts

Welcome to the Little Scouts exhibit. With a telescope, we can see distant objects clearly. But how does a telescope work? Simply put, a telescope consists of an objective lens and an eyepiece. The objective lens captures distant objects and forms a smaller image, while the eyepiece magnifies that image into a size visible to the human eye—allowing us to see faraway details. Depending on the eyepiece, telescopes are generally divided into Galilean telescopes and Keplerian telescopes. Here, you can switch between the two types of eyepieces and compare how each one shows you the distant scene.

Marching Figures

This exhibit is called Marching Figures. Rotate the disk, and the once-motionless little figures suddenly begin to walk. What’s happening here? This is an illusion created by the combined effect of the stroboscopic effect and persistence of vision. When we observe objects, light signals travel through the optic nerve to the brain, forming a visual image. After the light stimulus ends, the image does not disappear immediately—it lingers for about 0.1 to 0.4 seconds. This lingering effect is called persistence of vision. As the disk spins, figures in slightly different postures appear one after another. Because the previous image hasn’t fully faded before the next one arrives, the brain overlaps them into what looks like smooth, continuous movement. You can rotate the handwheel in either direction and watch the effect for yourself.

Magic Wand Imaging

Here we have the Magic Wand Imaging exhibit. Press the start button—what kind of patterns will the wand create? Amazingly, a simple stick can draw out a two-dimensional image. The principle behind this is again persistence of vision. When an object moves quickly, the image it leaves on the retina remains for about 0.1 to 0.4 seconds even after the object has passed. By moving the wand rapidly and combining these afterimages, our eyes perceive a complete pattern or a continuous motion effect.

Secrets of the Magic Mirror

This exhibit, Secrets of the Magic Mirror, demonstrates optical distortion. When a cylindrical mirror reflects an image, distortion occurs. Based on the principles of projective geometry, computers can deliberately distort an image so that when it’s reflected in the cylindrical mirror, the original undistorted image reappears.

The exhibit has three parts for you to try: First of all, place the cylinder on the red circle and observe how the distorted picture is restored in the cylindrical mirror; Secondly, press the button to switch to a different image and compare how the reflected image differs from the flat version; Finally, press the start button to set the disk in motion. Through the cylindrical grating, you’ll see a series of dynamic moving images come to life.

Amazing Optical Illusions

This is the Amazing Optical Illusions exhibit. Raise the background panel using the lever, and you’ll see the black and yellow squares moving in sync. Lower the background panel, and suddenly their movements appear out of step, as though they’re advancing alternately. Why does this happen? It’s caused by the striped background creating a visual illusion. When the black square moves across the black stripes, our eyes hardly notice its motion; it only becomes obvious when it crosses the white stripes. The yellow square is just the opposite—its motion is clearest on the dark stripes. This difference tricks our perception into thinking the two squares are moving at different rhythms, even though in reality they’re moving exactly the same way.

Is It You or Me?

This exhibit is called Is It You or Me. Two visitors sit in the chairs on opposite sides and press the button. Now, who do you see in the mirror? The secret lies in the half-silvered mirror (also called a semi-reflective, semi-transparent film). It reflects part of the light while allowing the rest to pass through. When the light on your side is stronger, you see your own reflection as if in a flat mirror. When the light on the other side is stronger, you see the person across from you, as though looking through transparent glass. If the light levels on both sides are nearly equal, the two images overlap—creating a fascinating blend of both faces in the mirror.

The Mystery of Color

Welcome to The Mystery of Color. Rotate the ball until two similar colors are side by side. At first glance, the two colors look clearly different. But when you block the dividing line between them, they suddenly appear almost identical. This happens because of the visual system’s edge detection mechanism. Retinal cells are highly sensitive to changes in color or brightness at boundaries. The dividing line provides a strong reference cue for distinguishing colors. Once the boundary is hidden, the colors appear “isolated,” and without the reference, the brain struggles to tell them apart—especially when the colors are already close in shade. When the color difference is large, however, you can still tell them apart even without the dividing line.

Fun with Imaging

This is the Fun with Imaging exhibit. Here, optical binocular recognition and tracking technology captures your movements in real time and projects them onto the electronic display screen. Step up and interact with your own digital reflection!

Incredible Photos

This is the Incredible Photos exhibit. Step into the scene and get close to Einstein himself. Invite your friends or family to stand on the floor marking the “best shooting position.” When you take a photo from that spot, the result will give you a vivid, immersive effect—like you’re really there with him.

The Invisible World

Here you’ll find The Invisible World. A 360° panoramic screen, created by six seamlessly joined projectors, brings unseen worlds to life. From the tiniest nanoscopic organisms to the vast expanse of outer space, optical instruments greatly extend the limits of human vision. The five viewing spheres in this hall showcase: the invisible world of infrared radiation; the invisible world of nanotechnology; the invisible world of X-rays; the invisible world of high-speed moments; the power of the telescope. Let’s explore together the wonder and technological beauty that optical observation tools reveal.

Exploring the Deep Sea

This exhibit is called Exploring the Deep Sea. It simulates the experience of a submarine lookout using a periscope to observe the ocean surface. The simplest periscope can be made with just two flat mirrors and a cardboard tube. The mirrors are set parallel to each other, both at a 45° angle to the horizontal. Light reflects twice and enters the eye, allowing you to see above the surface. The modern periscope was invented in the early 20th century. By 1906, when the German navy launched its first submarine, optical periscopes were already quite advanced. Today’s periscopes are enhanced with infrared imaging and laser range-finding technologies, enabling clear observation both day and night. Try out the simulated periscope here and see for yourself.

That concludes this hall. Please continue to the next exhibition hall—THE HISTORY OF LIGHT—and uncover even more optical wonders!