Wanting to test home built lidar jammer

[STiMULi]

That gives a whole new meaning to the name "BLINDER"

[Solion]

keep in mind this is is only 7.2 watts not the 75 watts the LI puts out ...

I'll assume that's peak power, because if it was average power you probably would not be reading this. What is the average power? I won't pretend to know all of the ins and outs of optical power: I don't. But here's my take:


You have 7.2 watts of power. At 90 Khz, that's one pulse every 11111 nanoseconds. If each pulse is 25ns in duration (with LED's it's most likely much longer!) you are transmitting .225% of the time. Average power would be around 16200 microwatts/16.2 milliwatts, at any rate several times that of the diode jammers. So, you're most likely already in the Class III zone. Please be careful!

Jim

The best way to calculate is if it is measured in watts for radiant flux and watts/steradian for radiant intensity, Ir Leds don't have a coherent beam like lasers do and falloff over distance is pretty seveare. So no real chance of cooking the eyeballs of people unless you are right up on it

Calculations for radiant flux are usually related to beams, However radiant power of a led must take in the division of the angle ( think cone shape) While an emitter may have 180mw/sr My angle of half intensity is 10deg.

But you are right ,you should be careful and I won't will be staring directly into at close range Best calcualtion here is my average output is between 3.4w- 4

Overall, however the effect of IR light is mostly heat. Unlike other wavelengths like UV that distroys biological structures . Infrared is much safer than visible light and has a lot less energy.
they use MASSIVE IR arrays for night filming of wildlife (on the order of 200watts) And IR led Flashlights all the way up to 4w are available anywhere . And millitary uses illuminators to 30w

SO no.... Im not going to put my eye out or anyone elses.

Hey it's as solid as sears
http://www.sears.com/shc/s/p_10153_1...0070921x00003a


The camera I use is a little webcam with the IR filter removed . works really well and easy to hook up to the lappy for stuff like this

[Lucky225]

That gives a whole new meaning to the name "BLINDER"

x2 I was thinking the exact same thing, i was BLINDED just WATCHING THAT ON *VIDEO* HOLY CRAP

[ELVATO]

The UL also throws jam codes, which if you are doing this brute style, you'll probably throw one.

But, as you said, this is a large step forward, especially for 40 bucks

[jimbonzzz]

Infrared is much safer than visible light and has a lot less energy.

But on the other hand, with visible light you can count on your blink reflex to limit your exposure. With IR, you don't have that luxury.

[Solion]

Infrared is much safer than visible light and has a lot less energy.

But on the other hand, with visible light you can count on your blink reflex to limit your exposure. With IR, you don't have that luxury.

True, but when people talk about IR/UV damage and blink reflex it is in relation to lasers and other coherent wavelengths of light, Now THATS dangerous.

The most massive difference between an Ir led and a IR laser with collumnating lens is energy diffused vs energy as a beam. and that is where allot of the confusion lays in the arena of damage to the eye. If I had 500mw in an expanding cone (such in a led) you have to calculate the energy reaching the sensor or your eye by the angle of that cone. Rough calculation is at 500mw at 3 feet with 10deg led you would be getting less than .03% of that energy into your eye, at greater distances the falloff is dramatic

A laser keeps most of its energy over a long distances. so at 3 feet that same power is gonna fry a little dark spot on our retina even at 1/2 the power. hell it will do it 10 feet , 20 feet , 30 feet.

Really its safer than most people think. The class 3 laser tag on the LE-10 was all about the rated wattage of the laser diode and did not recognize the lens that was spreading that beam out.. and well , they need to have it for the guy who sticks his eye up against the lens.

That said , I will take my camera today and record the IR comming from my space heater... you think my IR leds are bright? . wait till you see this thing.

[Lucky225]

Infrared is much safer than visible light and has a lot less energy.

But on the other hand, with visible light you can count on your blink reflex to limit your exposure. With IR, you don't have that luxury.

True, but when people talk about IR/UV damage and blink reflex it is in relation to lasers and other coherent wavelengths of light, Now THATS dangerous.

The most massive difference between an Ir led and a IR laser with collumnating lens is energy diffused vs energy as a beam. and that is where allot of the confusion lays in the arena of damage to the eye. If I had 500mw in an expanding cone (such in a led) you have to calculate the energy reaching the sensor or your eye by the angle of that cone. Rough calculation is at 500mw at 3 feet with 10deg led you would be getting less than .03% of that energy into your eye, at greater distances the falloff is dramatic

A laser keeps most of its energy over a long distances. so at 3 feet that same power is gonna fry a little dark spot on our retina even at 1/2 the power. hell it will do it 10 feet , 20 feet , 30 feet.

Really its safer than most people think. The class 3 laser tag on the LE-10 was all about the rated wattage of the laser diode and did not recognize the lens that was spreading that beam out.. and well , they need to have it for the guy who sticks his eye up against the lens.

That said , I will take my camera today and record the IR comming from my space heater... you think my IR leds are bright? . wait till you see this thing.

x2, lasers are concentrated and directed beams of light, unless, which I don't doubt with Solion, he makes the LED output brighter then the SUN, I don't think anyone needs to worry about being blinded

But even then, I've stared at the sun, and eclipses a lot as a youth and despite what they say on TV, my eye sight is a perfect 20/20

[Solion]

Here is a great example of what I am talking about when we talk about diffused energy, And the frequency of that energy. IR is very safe untill you get it shoved into coherent beams. First,take a look a picture of my 2000W space heater under the table.


THEN look at the video. I don't think anyone has any fears of looking at their space heater, In fact this throws out so much IR that even blocking the lens with my finger, the image is grey from the IR passing through it

[ame]http://www.youtube.com/watch?v=kftZavnxrUE[/ame]



I think it is great we ask these questions about safety because they do need to be asked, and through it we begin to understand a few things about how things work and how they don't.

ISn't science FUN! so the next question is this. if we can assure safety to the public and to ourselves. why not go for broke? Sufficient array of Leds (in the correct NM range) to blind the gun.

Well nothing really, except for power, and if you will throw a jam code or not. So lets talk about the first. Power...on average lets say we get a nice big PNP power transistor to flip with a lidar detector to fire an array of LED's how much would you need? well In amps to drive them about 10. about 4 watts minimum of Ir output should overwhelm the pulses from the gun. Could you do 20 - 30 - 100 , sure. but keep in mind the ammount of current you will need to switch and regulate.

Second, JAM codes... Sadly I don't have a Lidar gun , much less one that will throw a jam code. But IF we are not outputting a pulsed signal and just a constant ON will a gun see that as a jammer? or just a bright IR source.... Hmmmmmmm dunno , Only Cat4 can answer that one for me. Id say if he has a space heater to fire his gun at it and see if it pulls up a jam code. Just an idea in a long list of em

If you COULD jam with a solid on output, why not leave it on? .. well thats simple, you want a triggered on because the same system that jams the detector in the lidar gun will probly jam the detector in your laser/radar detector from light pollution (its why you cant see the stars at night in a city ) . and you want to know when you are being hit.

Why do I have a feeling the MIB or a hit squad is getting ready.....

[fulcrum]

A space heater is useless against a lidar.
Don't mix up "near infrared" (IR-A ; 700-1400nm) and "long infrared" (IR-C ; 3000-10000000nm). A photodiode (SI-pin diode) has 0 sensitivity in the IR-C spectrum.
You might be able to overwhelm a lidar with a non-pulsed IR source, but you will need a lot more power then 4 watt. You will probably need a very expensive, very dangerous and very power hungry cw ir laser. The receiver end of a lidar is designed to separate background noise (sunlight, xenon headlights etc.) from its short reflected ir pulses, and it does a very good job at it.

[The Chariot]

You might be able to overwhelm a lidar with a non-pulsed IR source, but you will need a lot more power then 4 watt. You will probably need a very expensive, very dangerous and very power hungry cw ir laser. The receiver end of a lidar is designed to separate background noise (sunlight, xenon headlights etc.) from its short reflected ir pulses, and it does a very good job at it.

A lot less expensive than you might think. You can buy 1.5 million candlepower IR spotlights and floodlights in the 900-950 nm range for about $150 - $250. Its non-laser. Basically a spotlight designed to put a huge amount of candle power in the approximate range and an IR filter to block out any visible light leakage. It'll plug into a 12 v power source such as a cigarette lighter. I linked to a couple of them in a thread somewhere here on the site, to discuss the feasibility of using one to brute force jam.