a white light - emitting diode 2 having high luminous intensity , such as a 240 lumen lumiled luxeon led , is actuated by a controllable analog voltage source 1 a and , via an optical waveguide 3 , irradiates the light - absorbing part of a photodiode 5 . a siemens bpw 34 is provided as the photodiode . a controller 1 for controlling the voltage of a plurality of such light - emitting diodes 2 , such as a computer , is provided . the computer 1 comprises the voltage source 1 a , which in the present example is a digital - to - analog converter . the photodiode 5 generates the desired current in accordance with the light intensity of the light - emitting diode 2 controlled by the voltage of the voltage source 1 a . the electrical contacts of the photodiode 5 are connected either to a straight wire 6 a in order to generate an electrical dipole , or to a wire 6 b which is wound in a coil shape in order to generate a magnetic dipole . such embodiments of the photodiodes are shown in fig2 to 4 . in fig2 , the electrically positive contact 22 and the electrically negative contact 23 of the photodiode are connected to each other at the back 21 of the photodiode by the electrically conductive wire 24 . in fig3 , the electrically positive contact of the photodiode 32 and the electrically negative contact 33 of the photodiode are connected to each other at the back 31 of the photodiode by the electrically conductive wire 34 wound as a coil having 20 turns . in the case of a two - color diode for the phantom according to the invention , the electrical contacts according to fig4 are positioned and connected to each other so as to generate an electrical dipole . at the back 41 of the photodiode , reference numerals 42 and 43 denote the positive and negative contacts of the electrical output of the two - color photodiode that is part of the first wavelength region . reference numerals 42 a and 43 a denote the electrically positive and negative contacts of the electrical output of the two - color photodiode that is part of the second wavelength region . the contacts are connected to each other , in the manner described , by the wires 44 and 44 a . alternatively , wire 44 and / or 44 a can also be replaced by a coil , as shown in fig3 . when the resistance is known , the magnetic or electrical dipoles generated by the light can be exactly calculated , in keeping with the designs of these current conductors and the ratio between the applied voltage and the applied current of the photodiode 5 , and the time line of the applied voltage , without having to take into consideration any interfering influence from any supply of energy . the dipoles generated in this way are captured in the measurement region 4 of the respective measurement system , the electroencephalograph or the magnetoencephalograph ( see fig1 ). it is a matter of course that a plurality of light - emitting diodes 2 , optical waveguides 3 , and specially configured photodiodes 5 can be used in the phantom , in keeping with the number and type of the dipoles to be generated , and can be connected to the voltage source and / or the controller .
a phantom comprises at least one first means for generating at least one dipole and at least one second means for actuating the first means in a non - electrical manner .