Single molecule force measurements Flashcards
1
Q
Optical tweezers Principle
A
Refraction and reflection of laser light in spheres (glass latex) with refractive index larger than surrounding (water)
2
Q
Calibration
A
- Determination of stiffness:
- Passive: Fokus position fixed, thermal motion measured
- Active: focus position moved, response measured
3
Q
Active Calibration
A
- constant motion
- jump response
4
Q
Laser
A
- Mostly IR laser (890 or 1064 nm)
- high power (some Watts!): avoid absorption!
5
Q
Position detection
A
- Camera
- Quadrant diode (+additional diode for z)
