Does the vial have a tamper-evident seal over a polyurethane stopper? Please tell us if the plastic tube is actually an isotope label. Expired pharmaceuticals? Cheers.
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"Education illuminates the compass directing us beyond imagination." c-MMV
What about the refractive index/flammability/photosensitivity of the liquid, the refractive index etc. of the bottle material, the irregular shape of the bottle, and the depth of the penetration you require?
Perhaps a laser isn't the way you want to go.
What's the description of the actual situation you intend to correct?