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M 2 is useful because it reflects how well a collimated laser beam can be focused to a small spot, or how well a divergent laser source can be collimated. It is a better guide to beam quality than Gaussian appearance because there are many cases in which a beam can look Gaussian, yet have an M 2 value far from unity. [1]
The square metre (international spelling as used by the International Bureau of Weights and Measures) or square meter (American spelling) is the unit of area in the International System of Units (SI) with symbol m 2. [1] It is the area of a square with sides one metre in length.
When measuring the beam parameter product and M 2, one uses the D4σ or "second moment" width of the beam to determine both the radius of the beam's waist and the divergence in the far field. [ 2 ] The BPP can be easily measured by placing an array detector or scanning-slit profiler at multiple positions within the beam after focusing it with a ...
1 feddan = 24 kirat = 60 metre × 70 metre = 4200 [2] square metres (m 2) = 0.420 hectares = 1.037 acres [3] In Syria, the feddan is a vaguer quantity, referring to the amount of land that can be ploughed by a pair of oxen in a year, being about 5–12 ha (12–30 acres). [4]
There was an average BSA of 1.73 m 2 for 3,000 cancer patients from 1990 to 1998 in a European Organisation for Research and Treatment of Cancer (EORTC) database. [19] During 2005 there was an average BSA of 1.79 m 2 for 3,613 adult cancer patients in the UK. Among them the average BSA for men was 1.91 m 2 and for women was 1.71 m 2. [20]
In the paper and fabric industries, it is called grammage and is expressed in grams per square meter (g/m 2); for paper in particular, it may be expressed as pounds per ream of standard sizes ("basis ream"). A related area number density can be defined by replacing mass by number of particles or other countable quantity, with resulting units of ...
E = the RMS electric field strength in volts per meter, H = the RMS magnetic field strength in amperes per meter. [6] The above equation yields units of W/m 2. In the USA the units of mW/cm 2, are more often used when making surveys. One mW/cm 2 is the same power density as 10 W/m 2. The following equation can be used to obtain these units ...
Modigliani risk-adjusted performance (also known as M 2, M2, Modigliani–Modigliani measure or RAP) is a measure of the risk-adjusted returns of some investment portfolio. It measures the returns of the portfolio, adjusted for the risk of the portfolio relative to that of some benchmark (e.g., the market).