Another IR Question

[SammieT 0]

Does anyone know of a type of "standard" bulb that emits more in the infrared spectrum than another? I have a light in my front yard that's mainly decorative (not intended as a flood or spotlight). I would like to keep the visible illumination fairly low but boost IR if that's possible. What I'm trying to accomplish is more illumination for security cameras without using traditional IR illuminators. I don't know if this is even possible but I figured if someone will know it will be someone on this board. Thanks in advance.

[VST_Man 1]

if your are trying to light up the yard the best way is a street light lamp type that is installed by your local electric company. ANY lighting will help. IR only works well when it reflects. ir into an open yard produces nothing but dark unless you aim the bulbs at "something".

[Cooperman 0]

Any 'hot' filament bulb will emit copious amounts of Infra red (for example, tungsten halogen bulbs).

 

Cooler sources such as fluorescent tubes, low / high pressure sodium, metal halide are all virtually useless for IR work.

 

The short answer is if you lit an area to around 25 lux using filament bulbs, or as an alternative low energy fluorescent tubes, the filament illumination will always provide the brighter image for a Black and White camera, simply because the bulb is emitting plenty of non visible Infra Red, which the camera can pick up.

 

In practice, it is generally the quantity of light, and not simply the frequency of light, which will dictate whether the image looks dark or not.

 

If you lit a room with reflected blue light, or covert IR light to the same level of illumination, the pictures produced by a suitable Black and White camera would be equivalent, although the 'grey' levels would appear different depending on the frequency reflectence of individual objects.

 

So as an example red curtains may look almost black under blue lighting, and almost white under IR lighting.