In:
Review of Scientific Instruments, AIP Publishing, Vol. 76, No. 2 ( 2005-02-01)
Kurzfassung:
An analog circuit which simultaneously performs radiation power and position measurement of an IR-laser spot (wavelength 1.3μm) on a four quadrant photodiode is presented and described. Its main features are 2MHz-bandwidth and low noise (14mVrms) for a nominal working radiation power of 2mW. This circuit has been implemented for the detection stage of an internal IR-laser deflection set-up, used to measure internal temperature gradients and free carrier concentration in vertical power devices. The measurements of the previously mentioned magnitudes inside the drift region of a 600V PT-IGBT are presented under critical operation conditions. This circuit, however, can also be used in other noncontact position and power radiation detection systems that require a high bandwidth and low noise levels. Moreover, the different noise sources along the detecting system have been identified. It is shown that the main contribution to the noise level at the processing circuit output is basically introduced by its second stage (analog divisor), assuring, for a 1mm laser spot centered at the photodetector, a maximum resolution in position measurement below 2μm.
Materialart:
Online-Ressource
ISSN:
0034-6748
,
1089-7623
Sprache:
Englisch
Verlag:
AIP Publishing
Publikationsdatum:
2005
ZDB Id:
209865-9
ZDB Id:
1472905-2
SSG:
11
