DIY Night Vision

[Klein1415]

Hello, I am making some night optics. I plan on integrating it into a mandalorian helmet of some kind. I'm trying to integrate a phone camera and IR LEDs into the rangefinder (the part that flips down) and create a HUD design using a small projector incorporated into the side of the helmet.
I plan on pulling parts from a motorola moto z2 force, as it allows for their modular system, which has a projector attachment. I would use an arduino with a switch on the rangefinder to control the power to the HUD and to the camera. However, I am very new to this level of electronic design, so any input would be greatly appreciated.

I do have a few questions already.
What would be the easiest way to limit the strength of the projector? I know I need full power to the LCD, but I don't want to blind myself with the full strength of the LEDs behind it.
Is there an easy way to make the phone a slave through bluetooth? I would like to be able to connect my phone to it to play music, record video, gps, etc.

 

[gophert]

What would be the easiest way to limit the strength of the projector? I know I need full power to the LCD, but I don't want to blind myself with the full strength of the LEDs behind it.

the easiest way is to get a transparent gray plastic to filter out some of the light.
the more practical way would be to add a manually controlled Pulse-width-modulated control of the backlight LEDs.

Is there an easy way to make the phone a slave through bluetooth?

Likely, the answer is "no" to the easy part of your question but you'll have to define "easy" to confirm.

 

[Klein1415]

For the projector, I was thinking about using a photoresistor to detect ambient light and using that to control the power to the LEDs. My experience with a photoresistor leads me to believe that the variability within the photoresistor is too great, and I wouldn't be able to directly wire it in series with the LEDs.

I have dealt with bluetooth modules through arduino, so I have a little experience. When I say "easy" I mean is it something that I could do without recoding the entire phone. I want to be able to do this with under 100 lines of code.

 

[gophert]

Ok, if you can write code, then an Arduino "analog" output does PWM. You may need a pass transistors to avoid drawing too much current from the Arduino gpio pin.

Now, if you can find the LED back light pins, it should be easy.

 

[Klein1415]

I thought of this earlier today.
Astronomers don't use white light inside their buildings, as it is easier for eyes to adjust from red light. Would it be possible/make sense to replace the white led with a red one, and have the output to the lcd be in black and white?

 

[unclejed613]

use green... red or blue lack definition under certain circumstances, the human eye is most sensitive in the green region, which is why real night optics use green.

 

[Klein1415]

That makes sense, thanks for the help! I'm still not sure how to go about dealing with the bluetooth. I don't need line by line assistance, but a relatively indepth explanation would be most appreciated.

 

[gophert]

Are you looking into a night vision camera (it can "see" body heat in the 7000 to 14000nm range) or are you talking about a standard digital camera without a nearIR filter and illuminating the area with near-IR L.ED?

 

[Klein1415]

Neither. Camera sensors automatically pick up ir light, so they come with a filter to block it out. I'm going to use the camera from the phone and remove the ir filter.

 

[gophert]

Neither. Camera sensors automatically pick up ir light, so they come with a filter to block it out. I'm going to use the camera from the phone and remove the ir filter.

there is not much IR light in the dark unless you have some 750 to 1100nm (near-IR) illumination (the kind of IR that simple digital camera can see). Good luck.

 

[Klein1415]

So the plan is to incorporate ir leds and a more powerful ir flashlight, with a rangefinder to toggle between the two.

 

[unclejed613]

i used to sell standard flashlight bulbs (with the incandescent bulb replaced by a resistor and IR-LEDs) specifically for night vision use... you may want to do some experimentation with some IR-LEDs and your camera... i know i had to do a lot of experimentation to get it right i sold two IR "flood" bulbs, one of them had one LED, and the other had two LEDs... then i had an IR narrow beam LED which worked well at several times the distance the "flood" LEDs worked at because it had about a 5 degree beamwidth as opposed to the 45 degree width of the "flood" LEDs. i did extensive testing to get the right amount of current, the right amount of illumination, and balancing that with battery life. i also had several visible LED bulbs (and these built into standard flashlight bulb bases after desoldering the glass bulb from the socket and installing a 10mm LED and dropping resistor). you will need to test IR LEDs with the camera you intend to use to make sure the emission spectrum is a good match for the IR that the camera will detect... iirc 750-900nm is about the wavelength range you are looking for...

 

[Klein1415]

Thanks for the info. I just got the phone and tested the camera, and it detects IR light from a TV remote. Do you know where I can get the IR-LEDs you were talking about? I see that Sparkfun sells some, but they aren't very bright, and only one wavelength.

 

[gophert]

Thanks for the info. I just got the phone and tested the camera, and it detects IR light from a TV remote. Do you know where I can get the IR-LEDs you were talking about? I see that Sparkfun sells some, but they aren't very bright, and only one wavelength.

how many wavelengths do you need?

 

[Klein1415]

I'm not sure. I am only going to use one, but I will need different wavelengths to determine the most effective wavelengths. Probably at least 3.

 

[gophert]

Digikey.com

search "IR emitter"

 

[Klein1415]

Thanks for that. I plan on testing 950nm and 850 nm, then using a larger emitter from digikey for the final build.

I am still unsure on how to connect the bluetooth. I do have coding experience, but little with android. Any help would be appreciated.

 

[Klein1415]

I have all of the hard parts, finally. I should just need to reassemble them, add a few buttons, and then change the code. However, within the process of reassembling everything, I have run into this adapter. It connects a pcb to a small projector, and I need an extension cable so I can put everything where it needs to be. Any help on what this specific connector is called and places where I can buy an extension would be helpful. I have looked for lcd extension cables, but I end up seeing several special specialized connections but nothing identical to this, at least in stock.