When you say light meter, we assume you mean Lux meter, not a photographic light meter.
Though a light meter can be used with a ceiling bounce comparing output to known lights.
Here is a link to what I did with PVC and a cheap lux meter.
I never got around to doing a write up on the finished version. Need to get off my butt and do that one of these days.
The ceiling bounce method is quite useful as long as you keep the conditions the same for each measurement.
Or you can re-calibrate with a known light for each test.
Or, perhaps the easiest solution, give Texas Ace a jingle and see if he has any calibrated lumen tubes left for sale.
