Cameras with blue leds?

[zs1 0]

I see a few cams on ebay and such that have blue LEDs, or perhaps IR LEDs that are tinted blue. Any purpose of this? They look... cooler I guess, but there's gotta be a reason for the blue tint. Does that block out the faint red glow you can see at night from the LEDs?

 

I tried googling the purpose of the blue tinted LEDs, but can't find a reason for it.

[Ken Layton 0]

A lot of late model pinball machines use those blue tinted infrared LED's and phototransistors to optically sense when the ball has passed certain areas of the playfield.

 

I'm assuming this tinting filters out all unwanted light so only pure infrared light is emitted/detected.

[CCTV_Tech 0]

I see a few cams on ebay and such that have blue LEDs, or perhaps IR LEDs that are tinted blue. Any purpose of this? They look... cooler I guess, but there's gotta be a reason for the blue tint. Does that block out the faint red glow you can see at night from the LEDs?

 

I tried googling the purpose of the blue tinted LEDs, but can't find a reason for it.

 

The newer high-efficiency Gallium Aluminum Arsenide (Ga1A) IR LEDs are tinted blue. The blue tinting is to shift the color and tinting also widens the viewing angle a bit.

 

950 nm IR LEDs are invisible to the human eye, while 850 nm is that red glow you sometimes see.

 

GA1A falls around 880-900nm, which is only faintly visible red for most people. Without the tint they would look a bit more red.

[beckosecurity 0]

As far as I know, there is no difference between white and blue IR LED except the color. One of my friend as a sales of IR LED told me about this.

[mike_va 0]

The newer high-efficiency Gallium Aluminum Arsenide (Ga1A) IR LEDs are tinted blue. The blue tinting is to shift the color and tinting also widens the viewing angle a bit.

However I've seen narrow angle available in dark blue from LED manufacturers.

 

The ebay cynic in me says they use to pretend they have better quality (e.g. looks like osram etc) as opposed to ultracheap LED's of questionable longevity and manufacture.

[vin2install 0]

There is no difference. The angle is not dependent on the color nor do the wavelength. Blue doesn't make it any more special or any more powerful.

It is just a tint.

[Fiona 0]

I am glancing out of my window at a recent installation of IR Dome Cameras at a neighbour's house. The IRs are inside the Dome and they emit red light which is obviously visible. From a distance of 50 feet or so, I can't see whether the red light is emitted from the IRs of from separate red LEDs. I spent a moment wondering why a manufacturer would go to the trouble of adding a visible light to the camera before the marketing angle dawned upon me.

 

What if the red lights are there simply to placate the buyer? In other words, the red LEDs (or blue for that matter) indicate to the customer that (a) the lights are on and (b) that they are working. The fact that the red LEDs are easy to see at night works to the advantage of the criminal because he or she can see in which direction the cameras are pointing. The addition of these coloured lights seems to be motivated by these marketing reasons which are entirely independent of the Infrared function.

[MaxIcon 0]

One possibility for the blue tint would be to remove some of the residual visible red in the 850 nM LEDs. The output spectrum from most inexpensive IR LEDs overlaps into the visible, as CCTV_Tech said, giving that dull cherry glow. If you filtered that part out, you'd lose some of the output power from the LEDs, but you'd also make them less visible when on.

 

Not all cameras are sensitive to the invisible 950 nM wavelength LEDs, and the 950 nM illumination devices tend to be a good bit more expensive, based on what I've seen recently.

 

As for alerting the criminal, that's a 2 edged sword. Many criminals are deterred by obvious video monitoring (meaning they go elsewhere to commit their crimes, not give it up), but if they're specifically targeting a location, they can take precautions if they know video is present (like masks and spray paint for the lens).