wha wtf???
I'm going to try to translate the questions..
1) How do I test a LED to compare to the data sheet?
2) Do I use an oscilloscope to check the current?
Sorry..need more info .
I cringe at how nonenglish the details will be.
D from BC
Did we fail to read the subject before we pounced on this poor fella?
If you want to measure the on/off time of an LED you might try using a
moderately high-speed photodiode; at least 2X faster than the LED
datasheet specification (some Nyquist thingy or something ?). Make
sure that the spectral response of your photodiode is appropriate for
the LED you are testing (i.e. the photon energy of your LED is greater
than the band gap of your photodetector). Silicon photodiodes will
work out to about 1.1 microns, InGaAs will work between 900 nm and 1.7
microns. Attach the output of your photodiode to the input of an
oscilloscope (again, the analog bandwidth of your o-scope must be at
least 2X the frequency you are trying to measure) and measure the
voltage drop across 50 ohm input impedance. You might need to use a
lens to focus the LED emission onto the photodiode in order to get
enough signal to make this measurement across 50 ohms. If you have a
high speed scope probe with small capacitance (~10 pf for a passive
probe these days) you can also make this measurement across a 1MegOhm
input impedance for a larger signal.
I know nothing about the subject matter at hand, but I hope this
helps
Did we fail to read the subject before we pounced on this poor fella?
If you want to measure the on/off time of an LED you might try using a
moderately high-speed photodiode; at least 2X faster than the LED
datasheet specification (some Nyquist thingy or something ?). Make
sure that the spectral response of your photodiode is appropriate for
the LED you are testing (i.e. the photon energy of your LED is greater
than the band gap of your photodetector). Silicon photodiodes will
work out to about 1.1 microns, InGaAs will work between 900 nm and 1.7
microns. Attach the output of your photodiode to the input of an
oscilloscope (again, the analog bandwidth of your o-scope must be at
least 2X the frequency you are trying to measure) and measure the
voltage drop across 50 ohm input impedance. You might need to use a
lens to focus the LED emission onto the photodiode in order to get
enough signal to make this measurement across 50 ohms. If you have a
high speed scope probe with small capacitance (~10 pf for a passive
probe these days) you can also make this measurement across a 1MegOhm
input impedance for a larger signal.
I know nothing about the subject matter at hand, but I hope this
helps
