I think the best option is to run that detector (both the amplifier side and the LED side) from a regulated 5V supply. However, the readings you are getting appear to be roughly ratiometric with the supply voltage. Therefore, if you feed the output into in analog input of an Arduino that is powered from the same 5V supply, then the ADC will approximately compensate for supply voltage variation.
thank for reply,
my readings are taken from arduino, and checked with multimeter, to get voltage i use bandgap for the adc ref voltage, so it does not compensate reading. to check adc i try the compensation why different voltage using other sensor, or using a simple resistor, and it works!, but this times not; i think is the output of this sensor that change with voltage supply changing, but datasheet unfortunately do not tell anything about sensitivity over voltage.
anyway, i suppose you are right, best option is to run it over regulated 5v power.