Fire-TICs Flir-One Lenses Project

Project 4

FLIR One with alternative lenses

This project takes a FLIR One phone camera and adapts it to a lens from an Argus3 camera, and then several other lenses. It uses the Android USB version of the camera, where capable phones from the Motorola G series can be obtained very cheaply from eBay if a dedicated processor-display is preferred, for example to build into a box.

Broken FLIR-One's from eBay are a bit of a mix, some will be battery issues while others can be poor soldering on the BGA devices of the main PCB - which is virtually unfixable for the enthusiast. More about that can be found on the EEVBlog forum.

	PCB assembly design showing FLIR One in place.
	PCB assembly design showing FLIR One in place.

Build Details

Disassemble the FlirOne, it is held together with sticky tape so does pull apart, but be careful with using sharp tools not to damage internal parts.
Extract the main PCB and the battery, keep the other bits in case you want to put it together again.
The FlirOne USB connector is 4 pins at 50 thou pitch but has no ground relying on a spring finger. For this build the spring finger is replaced by soldering a wire across.
Fit the 4 way header to the FlirOne in place of the USB adaptor PCB and position the FLIR unit with M2 screws and flush to the PCB [2]. Once in place and flat, solder the 4 pin header to the PCB.
Tighten and secure the M2 screws.
Add the grounding wire [1]
Stick the FLIR battery to the PCB, or replace with a Li-Ion cell and solder wires to the FlirOne. Placement options with the original battery are limited as the wires are quite short.
Make up the USB extension lead, using the FLIR part as a guide to pinout through to the micro USB

	Detail of FLIR One in situ [1] Ground connection wire [2] 4 way USB data [3] USB charge and charge LED [4] Switch and activity LED
	PCB design showing FLIR One connection and also fixing holes for various lens mounts from the Argus camera ranges. PCB data file is this zip
	The lens. In the fire camera design this 15mm focal length lens gave a 50° field of view but on a 320x240 50um pixel detector. With a FlirOne Lepton core having smaller 12µm pixels, and less of them at 120x160, the field is 5.5 degrees horizontal.
	Optical dimensions.
Parts Used	FLIR-One Motorola G4 phone Software 'Thermal Camera+' by Georg Freidrich App link Google Play far better than the FLIR version. Samtec FTSH-104-01-L-DV M2 screws, nuts PCB Argus3 Lens 15mm f/1 M3 screws, pillars Cable extension for USB Harwin M20 0.1" 5 way or similar and mating parts Micro USB rewireable plug (eBay) https://www.ebay.co.uk/itm/274508417065 Tripod mounting For a finished camera head you would likely also want to add: A box A handle Battery connector Battery 1 x lithium cell

Before going any further do a basic test to make sure the FLIR-One still works.
After charging up camera and phone, and found that a sequence of phone on - then connect - then turn on FLIR-One gives the most stable startup of camera+app. Phone App starts with the FLIR-One The image was as bad as you usually get with a FLIR-One without the MSX bodge of mixing in a visual image. In this setup of course the visual camera is just staring at a blank bit of PCB
I then set about refocussing the FLIR lens, which requires some disassmbly as the lens sits below the shutter.

Unsolder ground pin and lift FLIR-One off PCB
Unclip shutter
Refit FLIR-One to PCB and resolder the ground
Turn on and focus by turning the lens a little at a time, access from through the PCB. Unscrew to focus closer. Note that in this state you will need to cover the sensor from time to time and command a manual 'shutter' operation on the software, as refocussing needs access to the lens to undo it.
Refit shutter if desired

As can be seen this had a surprising effect, giving an almost reasonable image, which suggests the assembly process with the FLIR subcontractor in China does not include setting focus, just 'do up tightly'.
To fit the 15mm f/1 Argus3 lens

Unsolder ground pin and lift FLIR-One off PCB
Unscrew FLIR lens
Refit FLIR shutter. It still clips in place getting power from contacts on the Lepton sensor itself and is also held by the PCB.
Refit FLIROne to PCB and resolder the ground
Fit Argus3 lens on four M3 pillars

Videos & Images

Some images and short videos taken using the 15mm lens

Visual
Original Flir lens - but focussed
View 1
View 2
View 3
View 3

Final Thoughts

These images show that even just by focussing the lens the FlirOne can give much better imagery than as supplied. There is not much wrong with the Lepton at least for a scene with some contrast present. Moving up the quality curve on lenses helps both in resolution and as aperture reduces image noise. A 15mm is a good narrow angle choice, while not too narrow to aim sensibly.
Connecting to a mini-USB plug is not great, if you use too strong a wire then the plug breaks, use weak wire like Kynar and the wire breaks ! Using an adaptor PCB and unbodged cable would be better, but that needs finding a real fully wired 5 way OTG adaptor cable. So many are incompletely wired.
The battery is another weak point which would be best replaced. I have yet to find the correct connector but as this is the cause of many problems it is best avoided and again solder to the FlirOne PCB

Part 2 - let's try some bigger lenses .......Next Page

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Project 4FLIR One with alternative lenses

Build Details

Parts Used

Videos & Images

Final Thoughts

Part 2 - let's try some bigger lenses .......Next Page

Fire-TICs Project 5 page 24 November 2021 Images © M.W.Wilson All tradename © respective owners

Project 4

FLIR One with alternative lenses