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DIY Ulbricht Sphere for Laser Measurement

• 0:00 Error: no such column: None1:09 Solution: An Ulbricht Sphere, a hollow sphere with a highly reflective inner surface, can diffuse the laser beam, making it safe and suitable for measurement.
• 0:01:36 Building the Sphere: A small, spherical cake mold serves as the base. Two holes are made (with some difficulty) for light entry and exit.
• 0:03:38 Coating the Interior: Inspired by Les' Lab videos, Barium sulfate (BaSO4) is used for its high reflectivity across visible wavelengths and lack of fluorescence. It is mixed with water to create a paint-like substance.
• 0:04:22 Application Challenges: Applying the BaSO4 mixture to the unprimed, anodized aluminum is tricky, requiring multiple coats and careful handling as it doesn't harden.
• 0:05:04 Final Coating: A thick layer (approx. 14g) of BaSO4 is applied to the inner surface.
• 0:05:21 Testing with Lasers:
  • 0:05:29 Red Laser (5mW): The sphere successfully diffuses the light, preventing overexposure of the camera and making it easier to probe with a spectrometer.
  • 0:06:09 Stronger Red Laser (30x): Still works well, with the reflection showing significantly reduced intensity.
  • 0:06:38 Violet Laser (405nm): The sphere effectively reflects the violet light without fluorescence (unlike white paper), despite the human eye's low sensitivity to this wavelength.
• 0:08:01 Spectrometer Measurements:
  • 0:08:01 Red Keychain Laser: The sphere significantly reduces intensity, allowing for safe and stable spectrometer readings.
  • 0:08:31 Stronger Lasers: The small sphere size requires adjusting the probe distance for stronger lasers to prevent overexposure.
  • 0:08:46 Violet laser: No issues were found.
• 0:09:01 Infrared Laser Tests:
  • 0:09:03 808nm IR Laser: Reflected well.
  • 0:09:13 980nm IR Laser: Reflected less efficiently, requiring closer proximity and longer exposure times for measurement.
• 0:09:31 Overall Success The home made Ulbricht Sphere works great. It provides stable readings for little money and effort.
• 0:09:58 Future Plans: The creator considers building a larger, more video-friendly version, or possibly a 3D-printed version.