Device and method for measuring semiconductor-based light sources
Methods and devices for the sequential measurement of a plurality of semiconductor-based light sources that operate faster, more accurately and more sensitively than known methods and devices. In accordance with one implementation, a current pulse is applied by a pulsed current source to the low-luminosity light sources consecutively or simultaneously. The emitted light pulse of LED is converted into electric charge carriers by a photodiode, the electric charge carries are added up by means an integrator circuit, the added-together charge carriers are converted by an A/D converter into a digital signal and the digital signal is forwarded to a measurement and control unit.
1. A method for the sequential measurement of a plurality of optical pulses, comprising:
emitting pulsed light radiation into an Ulbricht sphere via an inlet opening,
measuring a first portion of the pulsed light radiation, which exits the Ulbricht sphere following interaction with the same through a first outlet opening, by means of at least one first detector and
measuring a second portion of the pulsed light radiation, which exits the Ulbricht sphere without interaction with the same through a second outlet opening, by means of at least one second detector, which measures the temporal progression of the individual optical pulses, wherein the second detector comprises a photodiode, an A/D converter connected thereto and a digital memory, which records the temporal progression of the voltage and/or the current of the photodiode, and wherein the second detector detects the temporal progression with a temporal resolution of 10 ns or less.
2. The method of claim 1 , wherein the second detector detects the temporal progression with a temporal resolution of 1 ns or less.
3. The method of claim 1 , wherein the second outlet opening is arranged opposite the inlet opening with respect to the central point of the Ulbricht sphere.
4. The method of claim 1 , wherein the first detector measures a radiometric parameter, such as the radiation output, and/or a photometric parameter, such as luminous flux.
5. The method of claim 1 , wherein the first detector is a spectrometer.
6. The method of claim 1 , wherein the first detector is a spectroradiometer.
7. The method of claim 1 , wherein the optical pulses are generated by a current pulse being applied respectively to an arrangement of a plurality of light sources simultaneously or consecutively by means of a pulsed current source.
8. The method of claim 7 , wherein the light sources are semiconductor-based light sources such as LEDs, VCSELs or OLEDs.
9. The method of claim 7 , wherein the conversion efficiency of light sources is determined from the ratio of the electric energy impressed by a current pulse and the energy of the individual optical pulses measured by means of the second detector.
10. The method of claim 7 , wherein the frequency of current pulses applied consecutively to the light sources is more than 100 kHz, and wherein the duration of an individual optical pulse is less than 1 μs.
11. The method of claim 7 , wherein the frequency of current pulses applied consecutively to the light sources is more than 1 MHz and wherein the duration of an individual optical pulse is less than 1 μs.
12. The method of claim 7 , wherein the frequency of current pulses applied consecutively to the light sources is more than 1 MHz and wherein the duration of an individual optical pulse is less than 100 ns.
13. The method of claim 7 , wherein the frequency of the current pulses which are applied consecutively to the light sources is more than 100 kHz, and wherein the duration of an individual optical pulse is less than 100 ns.
14. A device for the sequential measurement of a plurality of optical pulses, comprising: a pulsed current source, a photodiode, an integrator circuit, an A/D converter and a measurement and control unit which is configured to perform the method according to claim 1 .
15. A device for the sequential measurement of a plurality of optical pulses, comprising:
a pulsed current source configured to generate a current pulse being applied respectively to an arrangement of a plurality of light sources consecutively,
an Ulbricht sphere, which receives pulsed light radiation via an inlet opening,
wherein a first portion of the pulsed light radiation, which exits the Ulbricht sphere following interaction with the same through a first outlet opening, encounters a first detector arranged behind the first outlet opening,
wherein a second portion of the pulsed light radiation, which exits the Ulbricht sphere without interaction with the same through a second outlet opening arranged opposite the inlet opening, encounters a second detector arranged behind the second outlet opening, and
further comprising a measurement and control unit connected to the first and the second detector, whereby the measurement and control unit being configured to execute the method according to claim 1 .
16. The device of claim 15 , wherein the first and/or the second outlet opening is connected via an optical fiber to the first or second detector, respectively.
17. The device of claim 15 , wherein an optical fiber comprises an input and at least two outputs, the pulsed light radiation exiting the outputs at different intensities, wherein each output of the optical fiber is assigned a first or second detector.