Is it possible to see objects at 600m distance in infrared

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Discussion Overview

The discussion revolves around the feasibility of seeing objects at a distance of 600 meters using a 500 lumen torch equipped with an infrared filter and infrared goggles. Participants explore the implications of different types of infrared light, the specifications of the equipment, and environmental factors affecting visibility.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants question whether the goal is to see the beam itself or an object illuminated by the beam, suggesting that visibility may depend on environmental conditions such as mist or fog.
  • It is noted that the effectiveness of infrared goggles and the reflectivity of the scene will influence visibility.
  • One participant shares experience with a thermal IR scope capable of identifying distant objects, highlighting differences in technology and application compared to the original query.
  • There is a distinction made between thermal infrared and near-visible infrared, which may affect the outcome of the inquiry.
  • Concerns are raised regarding the assumption that the 500 lumen torch emits infrared light, with one participant suggesting that a standard flashlight may not produce any infrared radiation, potentially rendering the infrared filter ineffective.
  • Another participant emphasizes the lack of information about the infrared output of the torch based solely on its lumen rating, questioning the specifications of the infrared filter and goggles.

Areas of Agreement / Disagreement

Participants express differing views on the capabilities of the torch and goggles, with no consensus reached regarding the feasibility of seeing objects at 600 meters under the specified conditions.

Contextual Notes

Limitations include uncertainty about the infrared output of the torch, the specific characteristics of the infrared filter and goggles, and the impact of environmental conditions on visibility.

Calconceptofnumber1
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Hi I am wondering if it is possible to see the full distance of a 600m beam from a 500lm torch with an infrared filter and infrared goggles?
 
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Do you really want to look at the beam - or an object at the end of the beam that is illuminated?
To look at the beam, you would have to project it into a mist (perhaps up into a cloud).

As long as you are not looking through fog, there should be no problem.
Of course, it will depend on the goggles and on the reflectivity of the scene.
I would review the specs on the goggles.

I have used a thermal IR scope that was capable of identifying a swimmer at 2 clicks.
That's not the same as your situation for a couple reasons:
1) Thermal IR does not require illumination.
2) The device was considerably larger than goggles (roughly an 18cm aperture).
3) It had a price tag well over $200K - likely not what you are considering.

I have also used a portable IR scope - but for distances out to only roughly 150m.
That one had a price tag of about $120.
 
Also, it matters if you are talking about thermal or near visible infrared, (illuminated or self illuminating).
 
Calconceptofnumber1 said:
Hi I am wondering if it is possible to see the full distance of a 600m beam from a 500lm torch with an infrared filter and infrared goggles?
On taking a second look at your question, there is a problem. I was originally assuming that your 500 lumen torch was an IR torch - and that you were looking at it through a IR filter.

If it is a normal torch (aka "flashlight"), it may not put out any IR at all. So the IR filter could come pretty close to blacking the flashlight out all together.
IR will not travel through glass. So the light bulb will block a lot of the IR. If the flashlight uses a glass pane, that will block almost all of what's left.
 
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Calconceptofnumber1 said:
Hi I am wondering if it is possible to see the full distance of a 600m beam from a 500lm torch with an infrared filter and infrared goggles?

This is a confusing question: if your light output is specified with 'lumens', you have no information about the radiated power outside of the visible spectrum- there could be none, or there could be a lot. Then there's the issue about 'infrared filter/goggles': what is the passband of the filter, what is the detection band of the goggles?
 
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