The Real Double Slit Experiment.

Summary

This video offers an in-depth look at the double slit experiment, a classic physics demonstration with a twist. Unlike most videos that only discuss the experiment, this one showcases the actual setup and results. The creator uses slits as narrow as a few wavelengths of light, allowing for detailed observation under a microscope. The video reveals the intricate interference patterns that emerge when light passes through the slits, highlighting the experiment's complexity and beauty. It also details the process of creating the slits using lithographic photomasks and demonstrates the experiment with both green and red lasers, showcasing the fascinating details of quantum mechanics.

Takeaways

• 🎥 The video presents a unique take on the double-slit experiment, showcasing actual experimental footage instead of just discussions.
• 🔬 The experiment uses slits with a width of only a few wavelengths of light, which is narrower than most traditional experiments.
• 🔍 The study of the experiment is conducted under a microscope, allowing for a more detailed observation of the diffraction patterns.
• 🛠️ The creator made various slits ranging from 2.5 to 25 microns and varied the distance between them for the experiment.
• 📸 The video shows the cross-section of a laser beam passing through slits, resulting in an interference pattern of bright and dark bands.
• 🌟 The individual slits produce an interference structure before their light visibly interacts with the other, which is a key detail of the experiment.
• 📈 The interference pattern develops between the slits and is different from what would be expected if the intensities were simply added together.
• 👨‍🔬 The experiment is conducted using old lithographic photomasks, a photoresist layer, and UV-light exposure to etch the slits.
• 💡 Two types of lasers were used in the experiments: a green laser diode and a red helium-neon laser, with the latter having better beam quality.
• 🔭 The experimental setup includes a microscope that projects the light from the slits onto a camera's CMOS chip for detailed observation.
• 📹 The video demonstrates that the double-slit experiment has many fascinating details that are often overlooked in standard presentations.

Q & A

What is the main purpose of the video?

The main purpose of the video is to demonstrate the double slit experiment in a unique way, showing the actual experiment rather than just talking about it, and to explore the experiment's details with greater precision using very narrow slits.

Why is the double slit experiment significant even after more than 200 years?

The double slit experiment is significant because it demonstrates fundamental principles of quantum mechanics and wave-particle duality, which continue to be relevant and studied for a deeper understanding of the physical world.

What makes this video's version of the double slit experiment different from most others?

This video's version of the experiment uses slits with a width of only a few wavelengths of light, which is significantly narrower than those used in most experiments, and studies the diffraction under a microscope rather than at a large distance on a screen.

What range of slit widths were used in the experiment?

The experiment used various slits ranging from 2.5 to about 25 microns in width.

How did the presenter vary the experimental conditions?

The presenter varied the distance between the slits and used different lasers (a green laser diode and a red helium-neon laser) to study the diffraction patterns.

What is observed when a laser beam passes through the narrow slits?

After passing through the slits, the light spreads out in bright and dark bands, particularly in the direction perpendicular to the slits, showing an interference pattern that develops between the slits.

What is the scale at which the observed phenomena occur?

The phenomena observed in the experiment happen within a scale of 1 cubic millimeter.

How does the interference pattern from the double slits differ from individual slits?

The interference pattern from the double slits is quite different, showing a complex structure that develops between the slits and spreads out over the entire pattern, unlike the uniform bump that would result from simply adding the intensities of individual slits.

What materials and techniques were used to create the slits for the experiment?

The slits were etched using old lithographic photomasks, a photoresist layer exposed with UV-light in the pattern of the slits, and the chromium underneath was etched to create tiny transparent slits in the chromium layer.

How was the measurement setup arranged for the experiment?

The setup included a laser source (either a green laser diode or a red helium-neon laser), a disk with etched slits placed on a microscope table, a microscope to project the light onto a CMOS chip of a camera, and a beam splitter for directing the HeNe-laser's beam.

What was the role of the DIY maskless wafer stepper in the experiment?

The DIY maskless wafer stepper was used to produce the exposure patterns in the photoresist, which were essential for etching the desired slit patterns in the photomasks.