NLS-Glossary

M of an avalanche photodiode (APD) is defined as $M=\frac{Multiplied photo current}{Primary unmultiplied pho tocurrent }=\frac{I_{ph}}{I_{pho}}$ where Iph is the APD photocurrent that has been multiplied and Ipho is the primary or unmultiplied photocurrent.

is the excess noise in the photocurrent of an avalanche photodiode due to the statistics of the multiplication process occurring in the avalanche region. The avalanche process does nor occur continuously and smoothly in time but as discrete events whose frequency of occurrence fluctuates in the avalanche region about some mean value. Thus the multiplication M fluctuates about a mean value. The result of the statistics of impact ionization is an excess noise contribution,called avalanche noise, to the multiplied shot noise. The noise current in an avalanche photodiode (APD) is given by, $i_{n-APD}= {[2𝑒(I_{do} +I_{pho}) M^2𝐹𝐵]}^{1/2}$  where F is called the excess noise factor and is a function of M and the impact ionization probabilities(called coefficients). Generally, F is approximated by the relationship $F\approx M^x$ where x is an index that depends on the semiconductor, the APD structure and the type of carrier that initiates the avalanche (electron or hole). For Si APDs, x is 0.3 - 0.5 whereas for Ge and III-V (such as InGaAs) alloys it is 0.7 - 1.

 is a photodiode with a depletion region in which the field is sufficiently large for an avalanche multiplication of photogenerated charge carriers by impact ionization. The avalanche process in the APD occurs over a limited region of the depletion layer and the photodiode design allows only the multiplication of one type of carrier for example electrons for Si.

The average or the Mean filter corresponds to the arithmetic average/mean. Average = 1/n*(x1+...+xn). With the Laser line triangulation , this filter is used to "smooth" the profiles. To some extent, the Noise is suppressed. Significantly deviating values change the result clearly.

Ex: 4, 6, 7, 10, 19  Average = 9.2
If the outlier "19" should be less considered in the result, the values can be corrected using the Mean filter.

A bar code verification term. Expressed as a percent.                                                                                                                                                                                                     

is the number of atoms in exactly 12 grams of Carbon-12. It is $6.022 \times {10}^{23}$. . Since atomic mass is defined as 1/12 of the mass of the carbon-12 atom, NA number of atoms of any substance has a mass equal to the atomic mass, Mat, in grams.