Canon 5D Mark III sensor kill / 5D Mark III grillé au capteur à cause d'un laser
Explanation and a thought by an applied physicist: The CMOS video sensor in this camera captures voltages from a row of photodetectors at a time (each 1/60s). The photodetecters (operating in photovoltaic mode) transduce a group signal output charge (collected from photons incident on each pixel) during the integration time, which is (1/60)(e) seconds = approx. 0.045 sec. Light from a green laser has a "short" wavelength (~532 nm) and shorter wavelengths are absorbed in the first few microns of the photosensitive region of a CMOS. A Class IIIb laser will emit 4.6 x 10^18 photons per second, so the number of photons incident on a pixel in a second must be LESS THAN (5 x 10^18 photons/s)(0.045 sec)(3.14 x 3.0625 mm^2) / (28.7 mm x 19.1 mm)(8,200,000 pixel/mm^2) = 4.8 x 10^8 photons in the case of direct and constant illumination of the CMOS. The laser source has a diameter of 3.5 mm at a distance of 10m with a divergence angle of 0.17 mrad, so at a distance of 50m from each CMOS pixel, its diameter would be 8.7 mm (area = 3.14 x (4.35 mm)^2 = 59.4 mm^2). The CMOS in this example is constructed such that 70% of the area of each photodiode is optically opaque or reflective (shielded by transistors and metallic bus circuitry) so the max number of photons incident on a pixel in this case is about 2.3 x 10^7 which is not enough to melt copper. 2.3 x 10^7 photons will, however, excite copper electrons just enough to raise the temperature along a single analog->digital converter to disrupt the layer of tantalum nitride that gates (constrains) electromagnetic propagation along copper wires through a column bus, creating a logic non-function scenario (constant "open" voltage signal to MOSFETs along the bus) that causes the "gate noise" we can see as a red horizontal line. This line will be evident in all future images captured by this CMOS. Although the light made a physical change, destroying circuitry, it just as true that that laser "overcommunicated" with a logical circuit such that a passive information receptor became overloaded, killing the component by information density (or entropic brute force!) Most will not fully comprehend the implications of the previous sentence.
この程・・・・ディスコなどで強烈な光でカメラのセンサーが・・・・
今朝早く起こされて眠かったのに・・・・
今朝早くからバタバタ・・・・
