I was going to build a DIY Lepton based thermal camera as a compact simple ‘quick check’ device. Granted I was going to use the lepton 3 that offers 160 x 120 pixel resolution, but I can honestly say that the offer of the above detailed device for £100 made the idea of a DIY mini self contained camera redundant for me
Now before anyone gets too excited over this camera, a few things to note …….
Pro’s
1. The camera is self contained and very compact
2. The camera is Radiometric in that it can provide pretty accurate temperature measurements
3. High and low Temperature tracking is provided in the firmware
4. There is the ability to save images for later use in reports or just as a record of the scene
5. The camera provided emissivity adjustment which is important fir accurate measurements on various target surfaces.
6. This particular Lepton core deployment makes use of both the high and low gain modes for a temperature measurement capability of -10C to +400C
7. A close focus lens is easily added to the nice flat face of the casing for PCB work
8. It cost me £100 which fir such a complete solution is excellent value even in the current market if less expensive thermal cameras coming out of China…… IF the resolution is adequate for the task though !
Con’s
1. The camera uses the Lepton 2.5 core. This core uses 80 x 60 pixels so image will suffer pixelation on larger screens. FLIR use techniques to reduce the effect of such low resolution but it will always be at the lower end of useable resolution. The image is interpolated from 80 x 60 up to 320 x 240 on the LCD display. My usual threshold is 160 x 120 pixels but I went below that for this low cost camera that has its uses to me.
2. The Lepton core is not a great performer in low Delta T scenes like when looking at a plasterboard lined wall for the plaster dabs or battens ! It produces better images when there is decent temperature differential in a scene. Look at the above referenced video to see the difference in image noise content when looking at low Delta T and high Delta T scenes. Noise is a fact of life in microbolometer based thermography and, IMHO, only becomes a serious issue when low Delta T scenes are being imaged.
3. The lens on the camera is quite wide angle at 51 x 38 degrees so the Instantaneous Field Of View (IFOV) is relatively large per pixel. This is not that great an issue for many users but does tend to highlight the low pixel count in an image. You have to move closer to the target to gain more detail. A 24 Degree HFOV might have been a better choice for PCB work. Not a deal breaker for me though.
4.
I believe the saved images will be just images and not fully Radiometric image files that contain the temperature of every pixel within the scene. This prevents easy Radiometric analysis of the saved image on a computer, but spot temperature measurements should be present so it is not the end of the World. This should be considered if intending to analyse the thermal image after capture however. Correction, saved images are fully radiometric and analysis software is provided.
5. The camera uses a small, 2.4”, LCD display. This may be too small for some users ?
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