having a corresponding receiver connected thereto the refractometer housing protects the internal components including the transmitter from damage caused by test fluids and cleaning fluids application_number US 87759101 A description referring to fig1 through 3 an automatic hand held refractometer formed in accordance with a preferred embodiment of the present invention is shown and broadly designated by the reference numeral 10 refractometer 10 is of a type that provides digital measurement data in the presently preferred embodiment refractometer 10 uses optical means in combination with a photosensitive detector analog to digital conversion electronics for digitizing output from the detector and microprocessing electronics for evaluating the digitized information to provide digital measurement data as taught in commonly owned u s patent application ser no 09 842463 now u s pat no ______ which is hereby incorporated by reference in the present specification refractometer 10 includes a multiple piece assembled housing that generally comprises an upper housing portion 12 a lower housing portion 14 a sample well 16 mounted in upper housing portion 12 a display button panel 18 mounted in upper housing portion 12 a communication window 20 mounted in lower housing portion 14 and a battery cover 22 threadably attached to lower housing portion 14 upper.