|
 Technical
Specifications
With
UKAS Accredited Certificates of Calibration for Polarimeter
Standardization
A quartz
plate consists of one (or two) thin discs of optically worked
crystalline quartz mounted in a tube, forming a "standard"
sample for a polarimeter. These are the ideal standards for
quality control laboratories as the quartz plate comes with
a Certificate of Calibration accredited by UKAS, the United
Kingdom Accreditation Service. The UKAS mark on the certificate
of Calibration is your assurance that the laboratory (in this
case, Optical Activity Ltd.) issuing the certificate has been
stringently assessed by independent experts and that the measurements
are traceable to National and International Standards.
Optical
Properties of Quartz
Crystalline Quartz resembles an ordinary uniaxial crystal.
When a beam of light passes through such a crystal, the lights
is split into two beams polarized at right angles. In the
special case of uniaxial crystal cut perpendicular to its
optic axis, the state of polarization for a beam passing through
the crystal remains unchanged. Quartz however, is Optically
Active. This phenomenon of optical activity was discovered
in 1811 by Arago, who observed that with quartz, unlike an
ordinary uniaxial crystal, the plane of polarization is also
rotated with respect to the incident beam. A number of crystals,
both uniaxial and biaxial, are optically active, quartz being
the best known example.
Quartz
exists in two forms; one form, called Dextro-Rotary quartz,
rotates polarized light in a clockwise direction, Laevo-Rotary
quartz rotates in an anti-clockwise direction.
The specific
rotation of quartz (i.e. the rotation of a 1mm thick plate)
at a 20° C for light of wavelength 589.4400nm (sodium
yellow) is 21.7 degrees. Variations with both temperature
and wavelength are well known for quartz.
Optical
Activity Quartz Control Plates
All Optical Activity quartz controlled plates are manufactured
to the specifications laid down by I.C.U.M.S.A. (The International
Commission for Uniform Methods of Sugar Analysis) and are
available with or without the facility for temperature control
of the plates. The quartz disc or discs are mounted in a central
cell, which provides the best protection from dirt or careless
handling. In the temperature controllable version, the central
cell is thermally insulated from the supporting sections and
can be connection to a thermocirculator to control the temperature
by flowing fluid.
Optical
Activity quartz plates are supplied in a fitted wooden box
for safe storage.
Optical
Activity quartz plates can be used in most polarimeters, which
accept the standard 30mm diameter end collars. Optionally,
plates can be supplied adapted to fit polarimeters, which
require larger support collar diameters.
Standard
Rotation Values Available (normally ex-stock) are nominally:
Angular
Degrees +34°, +17° or +8.5°
International Sugar Scale (Z°) +99, +50 or +50
Other
rotations, either positive or negative, can be made to special
order. If a plate or rotation less than 8.5° (less than
25°Z) is required, this must be made as a double plate
because the minimum thickness of any quartz plate meeting
the I.C.U.M.S.A. specification is 0.4mm. Smaller rotation
standards are made by using one dextro and one laevo-rotary
quartz disc, the difference in rotation giving the required
positive or negative rotation. Any rotation up to 90°
can provide for general use in checking and calibrating polarimeters,
however only plates up to a maximum thickness of 1.6mm giving
a rotation of ±34° (100°Z) come within the
I.C.U.M.S.A. specification.
 Check
our credentials at UKAS.
Optical Activity is a UKAS accredited calibration laboratory
for the calibration of polarimeters and quartz control plates.
All Optical Activity quartz controlled plates are supplied
with the a UKAS accredited Calibration Certificate. The metal
mount is engraved with a serial number for unique identification
along with the optical rotation value at a temperature of
20° C and at the wavelength 589.4400nm (unless otherwise
requested). A temperature calibration table is also supplied
for each plate.
|
|
| Non-Temperature
Controllable Quartz
Plates |
Codes |
Dimensions
|
Wooden
Box Dimensions |
| 99°Z
(International Sugar Scale) |
03-01
|
Length:
120mm
Support
collar diameter: 30mm*
Maximun
height above optical centre: 15mm
Approx.Weight:
255g
|
Size
(lxdxh):
160 x 62 x 52mm
Approx.
Weight: 200g
|
| 50°Z
(International Sugar Scale) |
03-02
|
| 25°Z
(International Sugar Scale) |
03-03
|
| 34
angular degrees |
03-04
|
| 17
angular degrees |
03-05
|
| 8.5
angular degrees |
03-06
|
| Special
single plate, rotation to choice between 8.5 and
90 angular degrees (25 and 100°Z) positive or
negative |
03-07
|
| Special
double plate, rotation to choice between 0.5 and
8.5 angular degrees (1.5 and 25°Z) positive
or negative |
03-08
|
| |
| Temperature
Controllable
Quartz Plates |
Codes |
Dimensions
|
Wooden
Box Dimensions |
| 99°Z
(International Sugar Scale) |
03-01
|
Length:
172mm
Support
collar diameter: 30mm*
Maximun
height above optical centre: 45mm
Approx.Weight:
400g
|
Size
(lxdxh):
233 x 78 x 53mm
Approx.
Weight: 550g
|
| 50°Z
(International Sugar Scale) |
03-02
|
| 25°Z
(International Sugar Scale) |
03-03
|
| 34
angular degrees |
03-04
|
| 17
angular degrees |
03-05
|
| 8.5
angular degrees |
03-06
|
| Special
single plate, rotation to choice between 8.5 and
90 angular degrees (25 and 100°Z) positive or
negative |
03-07
|
| Special
double plate, rotation to choice between 0.5 and
8.5 angular degrees (1.5 and 25°Z) positive
or negative |
03-08
|
| |
03-11
|
|
*Larger
Diameters Available
Back
to Top
|
