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P5832 Refractometer PDF Download page

  • Index of refraction
  • Reflection by prism
  • Abbe's refractometer
  • Index of refraction of liquids
  • LED Beam collimating
Principle of operation
The spectral narrow-band emission of a LED is collimated and polarised and enters converging the prism. Due to the multitude of incident angles with respect to the hypotenuse of the prism a couple of rays leaving the prism whereas some rays are reflected and imaged via lens 2 on the optical screen forming a half shade. Under ideal conditions the shade is completely black. The position of the dark limit depends on the index of refraction at the hypotenuse.
  • Examples of investigations and measurements
An narrow-band chromatic LED (5) is used as light source. The output power is controlled by a digital controller (4) which automatically recognises the kind of connected LED and sets the proper injection current range by its software. The emission is polarised (2) by rotating the film polariser which is mounted into the holder (11). The left beam bending mirror assembly guides the beam via the lens 1 inside the prism assembly. The reflected beams are guided by the right beam bending assembly (19) and imaged on the optical screen (1). The liquid to be measured is applied to the hypotenuse of the prism and the offset of the limit of the half shade is measured by means of the vertical scale of the optical screen (1).
Finally the index of refraction is calculated by using the given formula for the instrument factor.
Measurements
The figures on the right are showing two test measurements. The figure A has been taken without any test liquid, that means zero measurement against air. The other one (figure B), has been taken with water on top of the prism. It clearly can be seen that in this case the half shade limit drops by 3 mm.
Entering this value into the respective equation the related index of refraction can be calculated and if necessary the instrument factors adapted.
A -air B - water  
The index of refraction of the provided liquids are:
Water: 1.33
Acetone: 1.36
sugar solution: 1.44
(60 Brix)
Set of test liquids
As test liquids contained in 15 ml dropping bottles water, acetone and a 60 Brix sugar solution is provided.
Brix is a definition of the content of the dry matter in a solution. If 1 g of sugar is solved in 99 g of water the solution has 1 Brix.
Other sugar solutions can be made very simple, the corresponding index of refractions are to be found in the provided manual.
  • P5832 Abbe Refractometer consisting of:
ItemCodeQtyDescription
12B-01801Optical screen, 40 x 80 mm with horizontal and vertical scale
24B-01421Polariser, click 25
36T-01001Set of test liquids
4ED-00101Adaptive power supply APS-05
5LS-00301LED amber
6MC-01001Screen holder on carrier 20
7MC-02601Profile Rail MG 65, 500 mm
8PM-01001Prism assembly
9PM-01101Bending mirror assembly 22.5° - 45°, left
10PM-01201Bending mirror assembly 22.5° - 45°, right
11XM-10901Mounting Plate, including carrier 20 mm, C 25
12XM-11101Adjustment holder, 4 axes, carrier 20 mm