Accession Number : AD0629542

Title :   REFRACTOMETER RESPONSE TO A HUMID ENVIRONMENT.

Descriptive Note : Scientific rept. (Interim), 1 Nov 64-31 Oct 65,

Corporate Author : UNIVERSITY OF WESTERN ONTARIO LONDON DEPT OF PHYSICS

Personal Author(s) : Hay,Donald R. ; Turner,H. Edward ; Ting,Chia-luan

Report Date : NOV 1965

Pagination or Media Count : 70

Abstract : The theory of the ellipsometric technique for observing the vapour layer on the sensing element of a refractometer has been examined and an assessment made of its precision of measurement. This instrument shows that an invisible layer of adsorbed water vapour forms on the sensing element of the refractometer at humidities exceeding 60 percent (for temperatures about 20C) and the depth increases to 1500 A as its refractivity increases to 1.025 near saturation. At saturation, microscopic droplets form on the sensor surface, apparently in association with surface contamination. The refractometer anomaly depends upon the method of vapour injection into the environment: it is the same for relative humidities increasing to 75 percent when the vapour is injected either by steam or by pan evaporation; at higher humidities, the larger vapour droplets from steam produce a greater anomaly in indicated refractivity. Vapour injection by slow evaporation produces a lesser anomaly than that by rapid evaporation; lower temperatures also are associated with smaller refractometer anomalies. Preliminary observations in the tunnel have been made at sub-freezing temperatures with different techniques of vapour injection. (Author)

Descriptors :   (*REFRACTOMETERS, ENVIRONMENTAL TESTS), (*HUMIDITY, REFRACTOMETERS), AIR, WATER VAPOR, OPTICAL PROPERTIES, ADSORPTION, CONDENSATION

Subject Categories : Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE