# Optical measurement kit

1. Overview
Japan’s optical technology is at the forefront of the world. But what about “optics” in school education?　This kit is designed to help students understand the basic properties of light intuitively through hands-on experience, rather than through a blackboard or textbook. The introductory optics experiment kit was developed by Uniopt based on an idea by Professor Kawabata of the Physics Laboratory at Tokyo Polytechnic University. The kit has been adopted as a theme for physics experiments. With this kit, you can intuitively experience the reflection and refraction of light. A variety of experiments can be performed by devising different combinations. The components of the kit are as follows.

2. Usage examples
• Reflection Law 1
Students learn that the angle of incidence is equal to the angle of reflection when light enters a mirror surface.

• Reflection Law 2
When light is incident on a mirror and the reflected light is observed. If the mirror is rotated by θ degrees, the reflected light will be deflected by twice the angle. This is commonly referred to as the θ-2θ relationship in reflection, and can be tested as follows.

• Refraction Laws
The kit contains prisms and lenses that allow you to observe the path of light passing through them. Can you see this in the following two pictures? If you draw an auxiliary line as shown in the right photo, you can explain Snell’s law, which is familiar from the textbook.

• Refraction of light by prisms
• Minimum declination
This is the most famous principle for studying the refractive index of prism materials. As shown in the figure, a prism is placed on a rotating table and a laser beam is incident on it. When the prism is rotated while observing the light spot on the screen, the light spot turns back at a fixed position. This position is called the position of minimum declination. To measure the refractive index, set the prism to this position and measure the angle of light swing at that time. The refractive index can also be measured by using the attached scale mount.

• Rainbow
If you change the light source to a white light source, you can observe the seven colors (spectrum) of the rainbow. So the white light is a mixture of the seven colors of the rainbow!

• Total Reflection
What is total reflection?　Isn’t it quite difficult to experimentally experience total reflection?　It is easy if you use a prism to see the path of light.

• Lens 1
A convex lens has the property of collecting light. As shown in the figure, use a half mirror and a total reflection mirror to divide the laser beam into three parts and set them so that each part is parallel to the other. You can see that the lens converges the light to a single point. Move the screen back and forth from the lens to the focal point and observe the distance between the three points of light.

• Lens 2
If you do the above experiment with white light, you will get the image on the right. (I think this one is easier.) Can you see the light trajectory in the lens, though it is faint?