An interesting article on night vision

Is it “adaptive” by itself i.e. it senses the ambient light or the colour of the surface being illuminated?

I am afraid not (yet)… “Adaptive” was one of the buzzwords in the early 1990ies when I did my ph.d. work in engineering (everything was called adaptive then). So I continue to use the term to make things sound more interesting

Adding a sensor for the ambient light should be no problem: a photodiode and a resistor is all the hardware required. I still have one unused analog input pin of the controller. That value could be used for setting the initial brightness when turning on the lamp. Sensing the colour of the illuminated surface is a bit more complicated. I will try to incorporate into the next prototype…

To continue this topic: I was able to find the time and installed Peter’s suggestion of an “adaptive” behavior into my night-vision-preservation-lamp. It was a lot easier that I originally thought, only two components were required: a photo-resistor and a plain resistor, connected to an unused analog input pin of the microcontroller. Everything else is already there. Double-clicking the on-off-button will start a 4-step measuring cycle. First, all lamps are turned off and the light of the environment is measured. This measurement will later adjust the overall brightness, very much like in most avionic units which have automatic brightness adjustment. Next, the colors red, green and blue are flashed in a brief sequence and the reflected light is measured. This measurement will set the colour of the lamp.

The German VFR ICAO chart for example is overall mostly greenish with labeling mostly in black:

Illuminating this chart with red light is not really good, because red is complementary to green. The background of the chart becomes very dark when illuminated by red light and reading black text from a dark background is very difficult. My lamp (I tried it out…) will set itself to the darkest possible yellow/green when used with the chart, resulting in black letters on a significantly brighter background – much easier to read. Unfortunately, due to the bad weather we are experiencing these days, I could not try it out in real life (telescope and airplane) yet.

I know that this whole exercise is mostly academic because paper charts have almost disappeared from both aviation and astronomy, but I think I gained a lot from the experience.

This is the simple modification to the lamp, I mounted the little photo-resistor in an aluminium tube underneath to shield it from the lamp’s own light:

Neat…

Aviathor wrote:

The G1000 I fly with is too dim if I leave it on auto-brightness. I need to adjust the brightness manually to around 10% at night.

That’s funny, I find the one I fly too bright, and have brought it down to about 1% which I find more comfortable.

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