Make a Periscope Reflection Guide

Building a simple periscope is a classic hands‑on activity that brings the science of reflection to life. By following a few straightforward steps, you can create a device that lets you see over obstacles, while simultaneously learning how light behaves when it encounters mirrors. This guide will walk you through the materials, construction, and the physics behind the periscope, making it an engaging experiment for students, hobbyists, and anyone curious about optics.

Materials and Tools You’ll Need

Before you start, gather the following items:

• Two small, flat mirrors (about 2–3 inches each)
• Two cardboard tubes or PVC pipes (length 12–18 inches, diameter 1–2 inches)
• Strong adhesive tape or glue
• Scissors or a utility knife
• Ruler and marker for precise measurements
• Optional: a small flashlight or LED for low‑light testing

Step‑by‑Step Construction

1. Prepare the tubes: Cut the cardboard or PVC tubes to the desired length. If using cardboard, reinforce the ends with extra tape to prevent fraying.

2. Attach the first mirror: Position the first mirror at a 45‑degree angle inside one end of the tube. Secure it with tape or glue, ensuring the reflective side faces the interior of the tube.

3. Insert the second mirror: Place the second mirror at the opposite end of the tube, also angled at 45 degrees, but oriented so that it reflects light from the first mirror toward the viewer’s eye.

4. Seal the tube: Wrap the entire assembly with tape to keep the mirrors in place and to block stray light from entering the tube.

5. Test the periscope: Look through the tube from the side opposite the mirrors. You should see a clear image of whatever lies beyond the obstacle. Adjust the mirrors if the image is blurry or misaligned.

Understanding Reflection in Your Periscope

The periscope works by exploiting the law of reflection: the angle of incidence equals the angle of reflection. When light strikes the first mirror, it bounces off at the same angle it arrived, traveling toward the second mirror. The second mirror then redirects the light toward your eye, allowing you to see objects that would otherwise be hidden. This simple principle is the foundation of many optical devices, from binoculars to telescopes.

By experimenting with different mirror angles, you can observe how the image changes. A 45‑degree angle is ideal for a basic periscope, but adjusting the angle can demonstrate how the path of light is altered. This hands‑on exploration reinforces concepts such as specular reflection and optical path length, which are essential in fields ranging from astronomy to engineering.

Extending the Experiment: Adding a Third Mirror

For a more advanced project, add a third mirror to create a three‑mirror periscope. This configuration allows you to see objects from a different perspective or to extend the viewing distance. The third mirror should be positioned at a 45‑degree angle relative to the second mirror, forming a right‑angle corner. This setup demonstrates how multiple reflections can be combined to redirect light over longer distances, a technique used in spacecraft instrumentation and satellite imaging.

Applications Beyond the Classroom

Periscopes are not just educational toys; they have real‑world applications. Military periscopes allow soldiers to observe enemy positions while remaining concealed. In underwater research, periscopes enable divers to view above the surface without surfacing. Even in everyday life, the principles of reflection help design optical instruments that improve vision and communication.

By building your own periscope, you gain a tangible understanding of how light behaves, which can inspire further exploration into optics, photonics, and even quantum mechanics. The skills you develop—precision measurement, careful alignment, and critical observation—are transferable to many scientific and engineering disciplines.

Safety Tips and Common Pitfalls

While constructing a periscope is generally safe, keep the following in mind:

• Use mirrors with a protective coating to avoid glare that could damage your eyes.
• Avoid looking directly into bright light sources through the periscope, as this can cause eye strain.
• Secure all components firmly to prevent accidental dislodging during use.
• When experimenting with larger mirrors or longer tubes, ensure the structure is stable to avoid tipping.

Common mistakes include misaligning the mirrors, which results in a distorted or invisible image, and using mirrors that are too small, limiting the field of view. Double‑check angles and distances before finalizing the assembly.

Conclusion: Reflect on Your Learning

Creating a periscope is more than a fun craft; it’s a gateway to understanding the fundamental principles of light and reflection. By manipulating mirrors and observing the resulting images, you actively engage with concepts that underpin modern optical technology. Whether you’re a student, a teacher, or simply a curious mind, this experiment offers a clear, hands‑on demonstration of how light can be redirected to reveal hidden worlds.

Ready to dive deeper into optics? Try building a periscope today and share your results with the community. For more advanced projects, explore resources on American Physical Society or Optica journals. Your next discovery could be just a reflection away!