IR Cameras and glowing red illumination

[bruno 0]

Of the IR cameras I have seen, the illuminators are visible at night as they glow red. Today I saw a camera advertised, and it claims it's IR illuminators are not visible like the others (no glowing red). Is this a hoax or does this technology exist? If it does exist, why don't all the IR cameras use these?

[AVCONSULTING 0]

You can have IR illuminators with no red glow but they have to be in the 940 nm range and that severely limits the distance you can see. Most people don't mind a dull red glow and would rather have that and extra distance. Only in the most covert operations would you need to have no visible light.

[Cooperman 0]

Bruno,

Hard to believe, but the technology has actually existed for over thirty years. They used to be called Silicon Vidicon and Extended Red Newvicon tubes (also Ultricons which were manufactured by RCA).

 

AVCONSULTING is spot on in his posting. Just a couple of things to add though;

The average B/W CCD sensor has very poor Infra Red (IR) sensitivity above about 800 - 820nM, so this means you need shed loads more IR light at the higher (invisible) frequencies, than you would at the lower frequencies, simply to achieve the same picture.

 

There are a few cameras that use very IR sensitive imagers, and these do cost quite a bit more than an average model, but the advantage is you get much clearer images even at distance with higher (covert) frequency IR.

 

One final point; Tungsten bulb based illuminators use a glass filter to block most of the visible light from the lamp, but they actually pass a spread of frequencies, so for example, with an 830nM illuminator, the actual IR frequencies passed may be between 745nM > 900nM (with maximum peak energy output at around the 830nM mark).

 

With LED based illuminators, the frequency band is much tighter, so you generally only have perhaps +/- 30nM against the manufacturers quoted figure.

 

I suppose the simple answer to your question as to why all cameras don't use covert IR, is simply that they'd cost too much for most applications.

[AVCONSULTING 0]

Adding to the previous post, if you want to use covert IR then you should use a camera designed for IR use such as the Extreme CCTV line of cameras.

 

 

http://www.extremecctv.com/home.cfm

[rory 0]

adding to this, Cooperman is living in the country with more Infrared Illuminators that any other country in the world the UK.

 

Also, If you want true Infrared follow AV's link. Extreme CCTV is widely used in the Uk, US and Canada, and with my help, in the Bahamas.

 

Basically, there are 3 approx. versions of IR.

750nm - Street Light Glow

850nm - Slight Glow

950nm - Invisible

 

Most BW cameras will work with 850nm.

 

Price doesnt matter much, but the camera itself does. If you are looking for a day night camera alot of them now will list in their specs what they work with as far as IR, GE Kalatel does that, for example. Extreme CCTV mostly designs its cameras for this.

 

Extreme has some great IR cameras, and if IR is what you want, outdoors, they will do it. Bullet IR cameras will not, generally.

 

IR domes- they can give off alot of glare, it is recommened NOT to use them, use a seperate Day/Night Dome and an IR LED. Trust me, I learned the hard way ($$). Seperate LED/Bulb is always better either way. For example, Extreme has cameras with an LED array seperate of the camera ($$).

 

If you need help with Extreme CCTV cameras, PM me.

[Cooperman 0]

Rory,

 

If you think we've got a lot of IR lamps, you should see the number of cameras!!

 

The most recent industry estimates say there are around 4.2 million CCTV cameras being used in the U.K.

 

The IR filter values for UK lamps have historically been based on 715nM & 830nM, with 850nM, 915nM, 950nM and 1000nM all being available at one time or another. Whilst it's right that most B/W cameras will work at 850nM, sensitivity is generally only around the 20 - 30% of that found when using visible light.