Why doesn't incense set off the smoke alarm?

Factual Questions
1

I was watching the cloud of smoke from the burning incense gather under a lamp and had to ask. It’s not very far from the smoke alarm (nothing in my place is) and closer than the kitchen. I’ve had the alarm go off from smaller amounts of smoke from the kitchen.

Enlighten, oh wise ones.

2

For that matter, why doesn’t cigarette smoke?

3

Smoke alarms ‘scan’ for particulate matter larger and more densely than what a cigarette or a small bit of incense produces. Keep on adding more and more cigarettes or incense, or, hold it right under the alarm and you’ll get it to go off.

4

I’m not about to try that! It seems strange that the smoke from the oven from burning some cheese is so much less visible than the incense, but set it off. I guess the incense is more stuff but so much smaller.

Thanks!