Tuesday, November 26, 2013

Why Do These Photos Of An LED Light Have Stripes?

At our Saturday eye exam, the eye doctor suggested using a stronger bulb in our reading lamps, to reduce eyestrain. Since we liked the result of putting an LED bulb in our Narnia lamp, we decided to get one for the reading lam; after all, it gets used almost every dayso it'd pay for itself eventually. Ieven had store credit at Home Depot, where they were available for about $7.
When I took the bulb out of the package, I noticed that it felt funny. Light bulbs normally have a rigid, hard and brittle feel, as a result of being thin glass. However this bulb was almost soft and slightly flexible - not visibly so, but to the fingers there was a tiny little fit of give. Upon contemplation, this appeared reasonable; there was no need for these bulbs to be gas-tight, so they did no have to be glass; a softer plastic actually made sense because it might resist damage were the bulb dropped.
The bulb went into the socket as designed; it was funny to look around that room and see that we had almost nothing that really needed 110 current; everything had some sort of transformer built in to step the electricity down to something like 6 volts. Perhaps at some point we'll go to a 6 volt house, and use rechargables for anything portant the needs more ooomph - like the vacuum.
We liked the way the bulb worked. It was noticeably brighter than the bulb it replaced, and seemed to have a fuller spectrum of colors. However when I took a photo with which to illustrate this blog, I noticed a striped pattern.
This pattern appears whenever I get a direct view of the bulb. When taking a picture of the bulb when it's lit, there is a strip pattern. Here are some examples. Any idea what causes that?

No stripes when bulb is not visible

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