What is small light in left side of turntable

[sudhirbhosale]

Hi
While going through turntable pics, I found two things for which I could not understand purpose:
1. I found smal LED type light Red/Blue on the left side of turn table focussing on edge of turning wheel
2. Many turn table have black and white chequered design (like chess bord)

What is purpose of these. are those ment to track the RPM and auto correct/calibrate?

Thanks

 

[jls001]

Please read this page:

How a turntable strobe works | eBay

 

[analogadikt]

turning wheel

This is known as platter in turntable terminology.

Regards