| The Sharples
Edge Stress Meter has been developed to offer a convenient method of measuring
the edge stresses in glass sheets. Amongst the applications are the measurements of edge stresses in : - 1. Laminated glass sheets; e.g. Windshields, Safety windows. 2. Toughened or tempered glass. 3. Heat-Strengthened glass. |
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The Sharples
Edge Stress Meter is a portable instrument which allows quantitative measurements
to be of stresses at the edges of glass sheets by employing the Senarmont
(or Friedel) method of compensation.
The measurement is taken from an analogue scale graduated in degrees and may be related to stress units such as Mega Newtons per sq metre or to an optical retardation measured in nanometres. A transparent scale is provided in the optical field which allows measurements to be made at distances of up to 50mm from the edges of the sheets. Measurements away from the edges are only possible where the principal stresses are parallel and perpendicular in direction to the edges of the ribbon. In toughened glass the principle stress directions are random. |
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The standard model accommodates sheets of up to 25mm in thickness. An adjustable magnifying lens, incorporating a monochromatic green filter, is provided for observing the interference fringes, visible near the edges of sheets, when taking quantitative measurements. The lens may be moved out of the field if desired. Dimensions: Length: 200mm Width: 90mm Height: 240mm |
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SHARPLES EDGE STRESS
METER FOR AUTOMOTIVE GLASS (REF. S-69) |
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This instrument has been specifically developed for measuring the stresses near the edges of automotive glasses with BLACK OBSCURATION BANDS. The instrument uses four of the latest LED spot lamps and works by reflective polarised light. Three of the lamps are green (wavelength = 514nm) for qualitative analysis and one of the lamps is white to identify a zero order fringe which is black in white light. As with our original Edge Stress Meter (Ref. S-67), this instrument is portable and measurements are made using the Senarmont Method of Compensation. The measurements is taken from the analogue scale graduated in degrees, which may be converted to stress units such as MN per sq meter or to an optical retardation in nanometres. Measurements can be taken to an accuracy of +/- 1 degree of rotation of the analyser, up to 75mm from the edge of the glass. |
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Stress pattern near the edge of the Black Obscuration Band |
SPECIFICATION Dimensions: Breadth (without handle): 150mm Width: 150mm Height: 260mm Weight: 2.6 Kg Lamps: 3 - GU10 LED LIGHTS
- GREEN Power Supply: 220 -240V/50Hz or
110V/60 Hz |
