Characteristics of optoelectronic discrete displacement converters with hollow and fiber light guides

Results and discussion
Analysis of the characteristics of bridge circuits shows that from the point of view of nonlinearity, the most preferable are circuits with two and four radiation receivers in the arms of the circuits (Fig.3, d).
Due to the fact that the considered ODCs are used in devices with built-in microprocessors, to match the ODC output with the microprocessor, preliminary processing of the output signal is necessary: amplification, conversion of the output voltage, noise suppression, etc. [2,3,4].
One of the most important elements of preprocessing ODPV signals are op-amp operational amplifiers (Fig. 3, d). At the same time, with the help of operational amplifiers, the sensitivity of the static characteristics of the DPPV is effectively increased and further converted into a discrete form.
For further calculations it is necessary to determine the relative values of e ₁ depending on the change in the total luminous flux , transducer radiation incident on the receiver [5] .
Let us analyze the dividing measuring circuit shown in Fig. 4, which is similar to the circuit in Fig. 3, a and can be considered as a chain consisting of series-connected resistances , to which the supply voltage U _{M is supplied as to the entire bridge circuit} . In this case, the voltage U _out across the resistance can be found from the expression:

,

( 10 )

where: U _M - voltage applied to the divider, I _C - current in the divider circuit.

Fig.3. ODC measuring circuits: a - dividing; b, c, d – pavements.

Since the magnitude of the photocurrent I _f is a function of the luminous flux incident on the radiation receiver and for small values of the luminous flux this dependence is linear, we can write

( 11 )

Where: - integral sensitivity .
Since the value of the dark current of the radiation receiver I _T is small compared to I _f , we can write:

( 12 )

Taking the latter into account, we can write:

( 13 )

or

( 1 4)

Substituting the values at x = X _min we find the following

( 1 5)

when x=X,

( 1 6)

From here we can write an expression for :

,

( 1 7)

And

(18)

Fig.4. ODC dividing measuring circuit.

(19)

K is the bridge symmetry coefficient .