Hall rotary encoder tempco--wisdom?

That would be a huge advance. I know, i monitored my blood glucose for about 3 months, with rather complete logging, to convince my doctors that i was not borderline diabetic. Hardly ever an pain or discomfort, just the nuisance factor. As a large secondary win, big cuts in the cost of supplies and the sharps disposal issues. You may reach individual users a lot faster than you think.

?-)

I imagine that sticking your finger all the time would get old fast.

The problem that has caused so much grief the is physiology, rather than the sensor _per_se_. Subcutaneous fat, calluses, and other such variations destroy the correlations you're working off.

It turns out that the right place to measure is in the web between your first and second fingers. The skin is always thin there, there's never any fat or callus, and there are two arteries right near by. (Not my idea, but I think it's very clever--the company has a patent on measuring there.)

If you can control the physiological variation, the actual sensor is pretty straightforward--you calculate the SNR and resolution, and then try not to screw it up in the detailed design.

Cheers

Phil Hobbs

Count your blessings. Labview is sort of like Excel or Arduino--easy to get twitching, hard to debug, hard to maintain, lots of non-obvious pitfalls. C++ for me, any day. (Of course I'm not attached to GUIs in general. Console code forever!)

The usual approach is a sine bar drive, i.e. you mount the grating on a pivot and use a ball-end lead screw to push it one way and a spring to pull it back. For small motions, the sine bar gives you a linear optical frequency scale. (When used with a fixed pivot, the lead screw actually sets the tangent of the angle rather than the sine, but it's still called a 'sine bar'. Go figure.)

The main source of repeatable error in your average sine bar drive is the runout of the ball on the lead screw.

Cheers

Phil Hobbs

On a sunny day (Tue, 14 Jan 2014 09:01:38 -0500) it happened Phil Hobbs wrote in :

I can recommend xforms (libforms, it is open source) in Linux. It even has fdesign, a GUI designer that outputs C code callbacks, where you only have to fill in your own code. I do not normally use fdesign, I like to make layouts writing by hand, but is is a help to get started I guess. Having done 100+ projects with it, it will do what I need. Unlike other GUI libraries that are often bloatware, libforms is only:

# l /usr/lib/libforms.so.2.0.0

-rw-r--r-- 1 root root 566148 May 3 2012 /usr/lib/libforms.so.2.0.0

Interesting, thanks. I've written a couple of OS/2 GUI apps down on the metal (or what passes for the metal in GUI apps, i.e. the OS APIs), but for the last 15 years or so I've mostly just done console code plus gnuplot or HTML for prettiness.

Cheers

Phil Hobbs

Well, some people are blessed with both inertial and volumetric advantages over others.

Coming to Photonics West this year?

Somebody once explained both the amplifier Miller effect and the beer Miller effect as "The more the gain, the more the capacity." ;)

'fraid not this year. Too many promises made to customers. (Not that I'm complaining about customers, you understand, but that whole spectrometer debug thing threw a monkey wrench into my plans.)

Cheers

Phil Hobbs

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Big time. You have to keep varying fingers, hands, and go elsewhere for really long term use. Particularly is you are actually diabetic, as it reduces healing significantly.

I think they deserve it.

Keep me in mind for field testing at the consumer level. I'm supposed to test four times a day, and the ends of my fingers are sore most of the time.