Testing Hypothesis

The setup:

  • 450x600mm glass mirror mounted on a tripod head with strong double sided mounting tape
  • Mirror was positioned so it was in view of the sun throughout the day
  • Window that the heliostat is targeting has a security mesh on the exterior face of the building and a thin curtain on the interior living room
  • A lux meter will be used to objectively measure the difference in ambient lighting

Part of the house is in perpetual darkness throughout the day as the sun travels from east to west. Sunlight struggles to reach the living room, making it less pleasant to use. This part of the year is the Autumn Equinox, we have approximately equal day and night exposure.

There is a significant difference (10 fold improvement) in the amount of light entering the room through the window when the heliostat targets the upper wall. I was unable to target the white ceiling as the room has a very high walls.

  • The maximum light level was around 580 lux towards the window, falling off to around 120 in the darkest part of the room.
  • Projection of the security bars was less noticable as a distance, a fuzzy cluster of light.
  • When an opaque diffuser like a polypropylene container lid is held in front of the beam of reflected sunlight, the projection of the security bars is focused and clearly defined.
  • An opaque diffuser did not affect the overall lux in the room but redirected the high concentration of light at the window to the container lid

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