Lens Question for Design of an Infrared Spotlight

In summary, the conversation revolved around building an infrared spotlight with the goal of lighting up a distant object on an IP enabled night vision camera. The main challenge was figuring out how to focus the light from an LED or cluster of LEDs onto a 40m tall object that is 400m away, using off-the-shelf cheap plastic lenses. However, it was mentioned that IR transparency and plastic are mutually exclusive and that using LEDs with a 6 degree beam angle may be a better solution. The conversation also touched on the use of IR optics and the fact that plastics are typically transparent in the near IR range.
  • #1
zlj06
3
0
Hello All.

I'm working on a project to build an infrared spotlight which will hopefully light up a distant object so that I can see it on an IP enabled night vision camera. The lens problem seems very straight forward, but I could use some help. Per the attached diagram, I want to focus the light from an led (or cluster of LEDs) on an object that is 40m tall, 400m away. Ideally, I'd like the LEDs + Optics to be housed in a piece of PVC pipe less than 2m long. Whats the easiest way to do this with off the shelf cheap plastic lenses?

Thanks for the help...
 

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  • #2
zlj06 said:
shelf cheap plastic lenses?
IR transparency and plastic are mutually exclusive.
 
  • #3
I'm not an expert but I suspect you will need more power than that type of LED can produce. How sensitive is the camera? Perhaps start with that and work back?

Perhaps you could use LEDs that have a 6 degree beam angle? No optics needed then.
 
  • #4
Bystander said:
IR transparency and plastic are mutually exclusive.

You might have to explain that. How do TV remote controls work if (at least some) plastic isn't IR transparent.
 
  • #5
  • #6
CWatters said:
You might have to explain that.
Just googled IR optics, and no plastic components.
 
  • #7
zlj06 said:
Great call CW! That's a much easier solution. Digikey has some very narrow radiation angle LEDs, so I'll solder together a cluster of those first and give that a try. Thanks, Zach
Bystander said:
Just googled IR optics, and no plastic components.
The LED in question is in the near IR, at 850 nm. Aren't plastics typically transparent there?
 

1. What is an infrared spotlight and how does it work?

An infrared spotlight is a type of lighting device that emits infrared radiation, which is outside the visible spectrum of light. It works by using a lens to focus the infrared light into a concentrated beam, making it ideal for illuminating objects or areas that are not easily visible with traditional lighting.

2. What are the important factors to consider when designing a lens for an infrared spotlight?

The design of a lens for an infrared spotlight involves several key factors, including the type of material used, the shape and size of the lens, and the desired focal length. Additionally, the lens must be able to transmit and focus infrared light while minimizing any distortion or aberrations.

3. How can the efficiency of an infrared spotlight be improved with lens design?

One way to improve the efficiency of an infrared spotlight is by using a lens with high transmittance for infrared light. This means that the lens should allow as much infrared light as possible to pass through without being absorbed. Additionally, the lens should be designed to minimize any reflections or scattering of the light, which can decrease its overall efficiency.

4. What types of lenses are commonly used in the design of infrared spotlights?

There are several types of lenses that are commonly used in the design of infrared spotlights, including refractive lenses, Fresnel lenses, and reflective lenses. Each type has its own advantages and disadvantages, and the choice will depend on the specific application and design requirements.

5. Can a single lens be used for both visible and infrared light in an infrared spotlight?

While it is possible to use a single lens for both visible and infrared light in an infrared spotlight, it is not recommended. This is because the materials and design considerations for visible and infrared light are different, and using a single lens may result in reduced performance for one or both types of light. It is generally more effective to use separate lenses for each type of light in an infrared spotlight.

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