Infrared and your sensor pad (pictures)

[FaultyClubs]

Hi all,

I was working on something not at all related to golf...but it involved making an infrared camera so I thought it might be educational to show infrared pictures of typical lighting and also explore the infrared world in which our sensor pads operate.

CFL versus Incandescent Lighting
Most everyone knows lighting is a big issue for the IR (infrared) sensor pads. But it is hard to visualize since we can't see infrared. So here are a couple pictures showing the difference between using a single 13 watt fluorescent 4100K bulb (sold as a "60W" equivalent) and a regular 60W incandescent bulb.

First, the 13watt CFL bulb (click on the images for a larger view):
IR-13w_flourescent4100.jpg

If you look very closely you can see my room. But it's pretty dark since there is hardly any infrared energy being emitted...just what we want in order to avoid room lighting and reflections interfering with our sensor pads. Note that to the naked eye the room is plenty bright to play golf in...in fact too bright when using a projector so I usually dim it down.

Now compare this with a 60W incandescent bulb:
IR-60w_incandescent.jpg
You might be temped to think I turned the light on! But I didn't! I just replaced the CFL bulb with a 60w incandescent and now there is infrared everywhere!

Remember to the naked eye my room looks the same in both pictures! But to the sensor pad there is a big difference! Clearly incandescents put out a lot of IR energy that will interfere with the sensors.


Sensor Pad and reflections
The next picture shows the two rows on my sensor pad, they are blindingly bright in IR and overloading my camera but to the naked eye they look very dim (faint red glow).
IR-OptishotPad.jpg

In this next picture I'm holding my 6-iron above the first sensor row. My irons are a dull finish but you can see the strong IR lighting reflecting from the sole. It's also interesting to see how much reflects off my hand. Note: the bulge is an artifact of my camera is overloading from the intense light.
IR-Optishot_IronRefection.jpg

This is what the Opti/P3pr pads see as they fire the powerful IR lights at the bottom of the club...and then try to makes sense of the reflections and turn it into something useful! And hopefully not be confused by reflections from anything else!

I didn't take pictures but it is interesting to observe how small changes in angle strongly affect the reflections. The size and shape of the reflection and its strength is all very sensitive to club shape, position and angles.


Infrared and tape
The final picture is a reminder that what something looks like to us is not necessarily what it looks like to the sensor pad!

I taped my club with two different black tapes. One was black electrician tape (out towards the toe) and the other was black hockey tape (towards the heel). To the naked eye, they both look black and one might think they would be equally good for taping a club to minimize reflections and lighting issues. But only one actually absorbs infrared and looks black, the hockey tape reflects infrared and looks white!

IR-BlackHockeyTape_vrs_BlackElectriciansTape.jpg

Neither tape is great at absorbing IR. The electricians tape at certain angles can have a pretty strong reflection. The hockey tape is actually brighter than the 6-iron (although if the 6-iron reflects straight back then it is much brighter) If you are trying to cover shiny bits on the bottom of your club then it's useful to realize that material behaves differently to IR than to visible light.

This is also important if you are trying to lay materials in your room to minimize IR reflections. Some carpets and fabric actually reflect IR (and look white in IR) while absorbing visible light (and looking black to us). I have some black fabric in my home theatre room used to absorb stray lighting...but under IR it actually looks bright white and doesn't absorb anything!

As an aside, note the golf ball in the last picture...they seem to be great reflectors of infrared.

A final miscellaneous comment, IR reflections can come from anywhere. Any window to natural lighting positively glows with IR. And the lights on my stereo system vary from invisible at infrared wavelengths to surprisingly bright. The projector is a bright IR source too (although luckily projectors are quite strongly focused on the screen and don't throw much IR light around the room...at least the IR energy is a lot less than the visible light...my projector was on in the tests above and generally helps light the room but you can see that the room appears very dark in IR).

Anyway, that's all I had time for. Hopefully some of you find it interesting.

[bubs3141]

very cool. It explains a lot thanks.