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Oxford Uni - Biological motors glossary
Category: Sciences
Date & country: 16/12/2007, UK
Words: 16


Acousto-optic Deflector
A solid-state device used for steering laser beams. Consists of a crystal of a material such as Tellurium dioxide (TeO2) and a piezoelectric transducer. A radio frequency signal input to the transducer generates a sound wave in the crystal which acts as a diffraction grating. The frequency of the signal determines the angle of deflection; the amplitude determines the intensity of the deflected spot. More details.

Boltzmann's constant
The value of Boltzmann's constant (kB) is 1.380 6503 × 10-23 J·K-1 ( NIST)

Critical Angle
The minimum angle of incidence at which Total Internal Reflection can occur. More details.

Evanescent Wave
The oscillating electric field produced at an interface where total internal reflection occurs; hence Evanescent Wave Microscopy (another name for TIRFM).

External Reflection
Reflection that occurs when light encounters a medium with a higher optical density (refractive index). More details.

Internal reflection
Reflection that occurs when light encounters a medium with a lower optical density (refractive index). More details.

Lorentzian
A curve describing the power spectrum of the motion of a trapped bead.

Oil immersion objectives
These objectives use an immersion oil between cover slip and lens to achieve a higher NA than is possible with dry objectives. They are corrected to yield the best results when looking through the thickness of a standard cover slip. (Focussing deeper into an aqueous specimen will cause spherical aberration).

Parseval's Theorem
This states that the integral of the power spectrum is equal to the total variance of a signal.

S1 (Subfragment 1)
A proteolytic fragment of myosin II consisting of a single motor domain and accompanying regulatory domain.

Snell's law
The law in optics governing the angle of a refracted ray:
n1 ·
sin θi = n3 · sin θt
(More Details)

Spherical aberration
Lens aberration where rays entering a lens at different positions come to a focus at different points. Often seen when focussing into a thick specimen with oil immersion objectives (Interactive tutorial).

Stoke's Law
The law giving the drag coefficient of a spherical object:
γ = 6·π·η·r

TIR - Total Internal Reflection
An optical phenomenon occurring at the interface between a medium of high refractive index and one of lower refractive index (e.g. quartz and water respectively). An incident ray of light will be totally reflected if it meets the interface at an angle greater than the critical angle.

yocto
SI prefix for 10-24 (See SI Units page at NIST)

zepto
SI prefix for 10-21 (See SI Units page at NIST)