How do Lasers Measure DISTANCE??

How do lasers measure distance?? Well there's 3 ways, but one of them is the best (in my opinion). Previous Video on Velocity:    • Self-Mixing Lasers: The Future of Speed Me...   0:00 - Introduction 1:39 - Reinventing the wheel 4:56 - The magic trick 10:59 - How to change a lasers frequency 16:21 - Conclusion