Linsseinä

Could you please clarify what Linsseinä refers to? Is it a real Finnish term in optics, ophthalmology, or another field? Could it be a place name (toponym) in Finland, or a fictional concept for a story or setting? With that context, I can draft a concise, neutral wiki-style article under 300 words. If you’d like, I can also proceed with a neutral stub that treats Linsseinä as a hypothetical term and outline plausible meanings (e.g., an optical boundary or a fictional locale) until you specify the intended use.