I Turned an Old Android Phone Into an Infrared Camera... Just Because I was Bored

Who would have thought that an old Android phone collecting dust in a drawer could become an infrared camera?

Well... apparently it can.

I honestly wasn't expecting much when I started this little experiment, but the results completely caught me off guard. The photos have this surreal, dream-like look that's impossible to get with a regular phone camera.

deep infrared photograph in Redmi 4X

Not bad for a phone that was basically destined for the junk drawer.

What Does an Infrared Camera Actually See?

Before we start tearing apart a perfectly good phone, let's spend a minute talking about infrared light.

You've probably heard the term before, but most people don't really think about what it means.

The light our eyes can see—what scientists call visible light—is only a tiny slice of the entire electromagnetic spectrum.

Seriously.

infrared spectrum next to visible light spectrum

Everything you've ever looked at since the day you were born has been filtered through a wavelength range of roughly 380nm to 760nm.

That's all our eyes are capable of seeing.

Right next to visible light sits infrared.

Its wavelength is a little longer, which gives it some interesting properties. Human eyes cannot detect it, but it can travel through fog much better than visible light and even penetrate a few millimeters beneath our skin.

Pretty wild when you think about it.

It also raises an interesting question.

If infrared light is literally all around us...

What would the world look like if we could actually see it?

So Why Use an Android Phone?

Taking the Camera Module Apart

If you've ever replaced an Android display before, this part probably won't scare you too much.

The camera module is tiny, though, so patience is far more important than fancy tools.

The goal here is to separate the lens assembly from the sensor without damaging the autofocus connector that hold the lens and sensor base together.

hot filter after being separated from the camera module

Some people try to bend the connector out of the way.

I didn't.

I simply cut it.

I know...

That sounds a little terrifying.

But for me it made the rest of the job much easier, and soldering it back together later wasn't nearly as difficult as I expected.

Sometimes making life easier now saves a lot of frustration later.

Removing the Filter

Now comes the part where things get interesting.

The hot mirror filter is usually sitting right on top of the CMOS sensor.

It's a tiny piece of glass with a slight reddish reflection.

Some camera modules are a little different and place the filter behind the lens instead, but either way, that's the piece we're looking for.

Removing it isn't difficult.

Removing it without scratching the sensor...

That's the real challenge.

I warmed mine with nothing more than a regular hair dryer to soften the adhesive.

After that, I carefully worked a razor blade underneath one edge.

Eventually...

Crack.

The filter shattered into several pieces.

Honestly?

I wasn't even worried.

The filter was going into the trash anyway.

The only thing that mattered was making sure none of those tiny glass fragments landed on the sensor.

Here's a small trick that helped me.

Hold the camera module upside down while prying.

That way, gravity works in your favor instead of against you.

If the glass breaks, the pieces fall away from the sensor instead of onto it.

Trust me...

You'll appreciate that little trick if your filter decides to explode like mine did

Cleaning the Sensor

With the filter finally out of the way, the next step is cleaning the sensor.

This is probably the most stressful part of the entire project.

hot filter in Android camera

At this point, one tiny speck of dust is enough to show up in every photo you take later. Worse yet, one careless move can permanently scratch the sensor.

Needless to say...

Take your time.

A simple air blower works perfectly for removing dust. Just don't go blasting it at full force.

And whatever you do...

Don't blow on the sensor with your mouth.

It might seem harmless, but tiny droplets of moisture from your breath can leave stains that are surprisingly difficult to remove. Those marks will show up in every single picture afterward.

Definitely not something you want after coming this far.

Before putting everything back together, it's worth checking whether the sensor is actually clean.

I connected the camera module back to the motherboard without installing the lens, powered up the phone, and opened the camera app.

If the preview looks nice and even—no dust spots, no mysterious streaks—you're good to go.

Congratulations.

Your phone is now officially missing its infrared filter.

Putting Everything Back Together

If you decided to cut the autofocus flex cable earlier like I did, now's the time to reconnect it.

A bit of solder, a steady hand, and you're back in business.

Once the cable is connected again, place the lens back onto the sensor and secure the module so nothing shifts around.

I simply wrapped a bit of tape around the module.

Not exactly elegant...

But it gets the job done.

Now reconnect the camera to the phone one more time and see if everything still works.

There's one thing you'll probably notice, though.

Removing the hot mirror filter changes the optical path ever so slightly.

In other words...

Your original focus point is no longer where it used to be.

To fix that, you'll need to rotate the lens little by little until everything snaps back into focus.

It's a bit of trial and error.

Take a picture.

Adjust the lens.

Take another.

Repeat.

Eventually you'll find the sweet spot where both nearby and distant subjects look sharp again.

Once you've done that...

Congratulations.

You've successfully converted your Android phone into a full-spectrum camera.

Wait...

Didn't we say infrared camera?

Not quite.

There's one last step. 

Turning It Into a True Infrared Camera

A full-spectrum camera captures much more than just infrared.

It also picks up visible light and even some ultraviolet light.

That's great if you're experimenting with different types of photography.

But for this project?

We only want infrared.

The easiest way to do that is by placing an IR Band-Pass Filter in front of the camera lens.

Think of it as a gatekeeper.

Instead of blocking infrared like the original hot mirror filter did, this one does the exact opposite.

It blocks almost everything except infrared.

You can find these filters online without too much trouble.

The most common options are 720nm, 850nm, 860nm, and 940nm.

Which one should you choose?

That depends on the kind of photos you're after.

Generally speaking, lower wavelengths let in a bit more visible light, giving you more color to play with.

Higher wavelengths produce stronger contrast and a much moodier look, but most of the color disappears along the way.

For the photos in this article, I used a 940nm filter because I really liked the dramatic black-and-white effect it produces.

Don't Want to Buy a Filter?

No problem.

There's actually a fun DIY alternative.

If you happen to have a couple of old LCD polarizer sheets lying around, try stacking two of them together at a 90-degree angle.

To your eyes, they'll look almost completely black.

Seriously...

You can barely see through them.

But place them in front of an infrared camera, and suddenly they become surprisingly transparent.

DIY infrared filter made from stacked LCD polarizers (middle)

The image won't be as clean as a proper IR filter, but it's good enough if you're just curious and want to see what infrared photography looks like.

Another trick people often use is a piece of transparent plastic colored with a black permanent marker.

Sounds a little ridiculous.

I know.

But believe it or not...

It actually works better than you'd expect.

Sometimes the best DIY projects are held together by tape, random plastic scraps, and a little bit of curiosity.

Final Thoughts

Looking back, this was one of the most enjoyable phone mods I've ever tried.

Not because it makes the phone more powerful.

Not because it improves the camera.

But because it lets you see something you've literally never been able to see before.

It's strange walking around familiar places and watching them transform into something that feels almost alien.

Trees glow.

Bright skies become darker.

Fog suddenly isn't much of an obstacle anymore.

It's the same world...

Just through a completely different kind of light.

And honestly, that's what makes this project so much fun.

If you've got an old Android phone lying around with nothing better to do, why not give it a second life?

Worst case?

You learn something new.

Best case?

You end up with a camera that's guaranteed to make people ask,

"Wait... how did you take that photo?"

Oh...

One last thing.

I've also included a short infrared video that I recorded at work a while back.

Yep.

Infrared really does cut through fog better than visible light.

It's pretty cool to see it in action.

OMG... it can see through smoke!  Now I am wondering... what else can it see through? 🤔