Device and method for radiometric measurement of a plurality of samples
The invention relates to a method for photometrically investigating sample radiations of at least one sample, which are caused by the radiation of N emitter elements of at least one radiation element wherein said N emitter elements are emitting radiation during time periods which at least partially overlap, to detect the sample radiation of at least two samples as a sum signal during time periods which at least partially overlap and to evaluate the sample radiation of at least one individual sample from said sum signal.
1. Method for radiometrically investigating N (N is a natural number with N>1) sample radiations of at least two samples, which are caused by the radiation of N emitter elements of at least one radiation element wherein said N emitter elements are emitting radiation during time periods which at least partially overlap, wherein the sample radiation is fluorescent light, comprising the steps:
determining a set of N basic frequencies,
adding one reference frequency to each of said basic frequencies wherein said reference frequency is higher than each of said basic frequencies,
using the N sums of the reference frequency and of the basic frequency to provide N modulation signals wherein each modulation signal is used to modulate the radiation of a different emitter element,
detecting the N sample radiations as a sum signal wherein each sample radiation is modulated according to the modulated radiation which caused the respective sample radiation,
demodulating the sum signal by using a demodulation method,
performing a transformation to transfer the demodulated sum signal from a time dependent signal into a frequency dependent signal, and
determining the quantity of at least one individual sample radiation from the amplitude of said frequency dependent signal in dependence of the basic frequency.
2. Method according to claim 1 characterized in that the N basic frequencies are chosen from a frequency range of 0 kHz to 1 MHz.
3. Method according to at least one of the previous claims characterized in that the reference frequency is at least as high as each of said basic frequencies multiplied by 2.
4. Method according to claim 2 characterized in that said N basic frequencies are chosen from a frequency range of 0 kHz to 4 kHz.
5. Method according to claim 1 characterized in that it further comprises a step of digitizing said sum signal and/or a step of digitizing said demodulated sum signal by sampling and A/D-converting.
6. Method according to claim 1 characterized in that it further comprises a step of averaging said sum signal and/or a step of averaging said demodulated sum signal over the time.
7. Method according to claim 1 characterized in that it further comprises a step of filtering said sum signal by a digital high-pass filter prior to demodulation.
8. Method according to claim 1 characterized in that the demodulation method demodulates said sum signal by multiplying it with the reference frequency.
9. Method according to claim 1 characterized in that the demodulation method demodulates said sum signal by performing a digital calculating.
10. Method according to claim 1 characterized in that a further step of sub-sampling is performed.
11. Method according to claim 1 characterized in that the reference frequency is chosen from a frequency range of 80 kHz to 120 kHz.