Sample cell for polarimetry, polarimeter, and polarimetry

A sample cell for polarimetry is disclosed. It comprises: a base member having a tubular cavity for holding a specimen and for permitting a light to transmit therethrough, and a pair of light-transmitting windows for sealing a pair of open ends of the cavity; and a coil arranged around the base member for generating a magnetic field inside the cavity along an axial direction of the cavity. The specimen is supplied to the cavity through a channel for communicating the cavity with the outside.

BACKGROUND OF THE INVENTION 
The present invention generally relates to polarimetry (measurement on 
optical activity of specimen, expressed in angle of rotation), and more 
particularly to an improvement in a sample cell for accommodating a liquid 
specimen subjected to the polarimetry. 
The polarimetry has heretofore been applied to identification, examination 
on purity, determination, and the like of a solute in a liquid specimen. 
Specifically, the polarimetry is employed in determining the 
concentrations of fructose, sucrose, glucose and the like contained in an 
aqueous solution. In recent years, an application of the polarimetry to an 
examination of urine sugar value (glucose concentration) or urine protein 
value (albumin concentration) is also proposed (International Patent 
Publication No. WO 97/18,470). 
An angle of rotation ".alpha." of a solution containing optically active 
substance is directly proportional to a product of a specific rotatory 
power "[.alpha.]" of the optically active substance and a concentration 
"C" thereof. If it is assumed that the length of the light path for the 
measurement is "L", then the angle ".alpha." is represented by the 
following equation (1): 
EQU .alpha.[degree]=L[cm].times.[.alpha.].times.C[kg/dl] (1) 
It is therefore possible to derive a concentration of the optically active 
substance contained in the liquid specimen by measuring the angle of 
rotation of the liquid specimen. 
One of the conventional methods of examining sugar or protein in a urine 
includes a use of a test paper impregnated with a reagent. The test paper 
is dipped in the urine and a color reaction thereof is observed by a 
spectrophotometer or the like. In this method, expendable supplies such as 
test papers are required. 
Glucose and albumin in the urine demonstrate optical activities but the 
other components in the urine do not demonstrate the optical activity. In 
view of this point, the above publication proposes derivations of the 
urine sugar value and urine protein value by the polarimetry on the urine. 
According to this method, even if the glucose or the albumin contained in 
the urine is small, it is possible to determine the urine sugar value or 
urine protein value without using any expendable supplies. In this 
publication, the rotated angle of the plane of vibration i.e., the angle 
of rotation, is directly derived by projecting a light having a particular 
plane of vibration on a specimen to be detected and detecting a plane of 
vibration of the light transmitted through the specimen by using a rotary 
analyzer. 
An example of the conventional polarimeter is shown in FIG. 15. A light 
source 81 configured with a sodium lamp, a band-pass filter, a lens, a 
slit and the like projects a substantially parallel light composed of a 
sodium D ray having a wavelength of 589 nm. A polarizer 82 transmits only 
a component that has a specific plane of vibration coincident with a 
transmission axis thereof, out of the light projected from the light 
source 81. A sample cell 83 for holding a specimen to be determined is 
arranged so that the light transmitted through the polarizer 82 can 
transmit therethrough. An analyzer 84 transmits only a component that has 
another specific plane of vibration, out of the light transmitted through 
the sample cell 83. An analyzer rotator 85 is for rotating the 
transmission axis of the analyzer 84 in a plane perpendicular to the 
direction of the advance of the light. An photosensor 86 is for detecting 
the light transmitted through the analyzer 84. The computer 87 controls 
the analyzer rotator 85 while recording and analyzing an output signal 
from the photosensor 86. 
The principle of this polarimeter for the measurement will be explained as 
follows. In FIG. 16, the abscissa represents the relative angle ".THETA." 
formed between the light transmission axis of the polarizer 82 and the 
light transmission axis of the analyzer 84, and the ordinate represents an 
intensity "I" of the light that has reached the photosensor 86, i.e., the 
output signal of the photosensor 86. Herein, the solid line indicates the 
output signal in the case where the specimen to be determined demonstrates 
no optical activity. Under this condition, the relationship between 
".THETA." and "I" is represented by the following equation (2): 
EQU I=T.times.I.sub.o .times.(cos .THETA.).sup.2 (2) 
where, "T" is transmittance of the specimen, and "I.sub.o " is an intensity 
of the light incident upon the specimen. Herein, a transmission loss and a 
reference loss of the sample cell 83 and the analyzer 84 respectively are 
ignored. As shown, a point where "I" reaches its minimum (hereinafter, to 
be referred to as "extinction point") appears for every .pi. with the 
variation in ".THETA.", i.e., the rotation of the analyzer 84. 
In a case wherein the specimen demonstrates an optical activity and its 
angle of rotation is ".alpha.", the intensity "I.sub..alpha. " of the 
light that reaches the photosensor is represented by the dashed line in 
FIG. 16. The intensity "I.sub..alpha. " is given by the following equation 
(3): 
EQU I.sub..alpha. =T.times.I.sub.o .times.{cos (.THETA.-.alpha.)}.sup.2(3) 
As seen from this, the extinction point of the specimen which demonstrates 
an optical activity displaces by ".alpha." as compared with that of the 
specimen which does not demonstrate the optical activity. It is therefore 
possible to measure the angle of rotation by finding the displacement of 
the extinction point by the computer 87. In the case of such polarimeter, 
S/N ratio in the output signal of the photosensor 86 is however 
comparatively inferior and it is difficult to accurately determine the 
position of the extinction point. As a result, it is difficult to measure 
the specimen having a small angle of rotation with high accuracy. 
For this reason, there has been proposed another polarimeter which makes 
use of optical Faraday Effect, i.e., a phenomenon that when a light is 
permitted to transmit through a medium while being applied a magnetic 
field along the direction of its transmission, the direction of 
polarization of the light rotates with the advance of the light. 
The optical Faraday Effect is represented by the following equation (4): 
EQU a=V.times.H.times.L (4) 
where, "a" represents an angle of rotation of the plane of vibration of the 
light [minute], "V" is Verdet's constant of the medium [minute/A] and "L" 
is a distance of transmission [m]. Herein, "V" varies with a medium, 
wavelength of light or temperature. 
As one which utilizes this optical Faraday effect, there is an optical 
Faraday modulator. The optical Faraday modulator includes, for instance, a 
rod of flint glass and a solenoid coil configured around the rod. When a 
current is flown through the solenoid coil for generating a magnetic field 
inside the rod while permitting a light to transmit through the rod along 
an axis of the rod, the plane of vibration of the light propagating inside 
the rod rotates. By controlling the intensity of the current flown through 
the solenoid coil, it is possible to vary the angle of rotation of the 
plane of vibration at will. 
An example of the polarimeter which employs the optical Faraday modulator 
is shown in FIG. 17. In this figure, parts and components which are 
identical with those used in the polarimeter shown in FIG. 15 are tagged 
with the same reference numerals. 
The optical Faraday modulator 88 vibrates the plane of vibration of a light 
transmitted through a polarizer 82 by a modulation signal from a signal 
generator 89. A lock-in amplifier 90 is for phase sensitive detection of 
an output signal from the photosensor 86 with reference to the 
vibration-modulated signal from the optical Faraday modulator 88. 
In FIG. 18, the abscissa and the ordinate represent ".THETA." and the 
output signal "I" of the photosensor, respectively. Herein, FIG. 18 shows 
the extinction point and the neighborhood thereof in an enlarged view. 
When the optical Faraday modulator 88 vibration-modulates the plane of 
vibration with an amplitude of ".delta." and an angular frequency of 
".omega.", "I" is given by the following equation (5): 
EQU I=T.times.I.sub.o .times.(cos 
[.THETA.-.alpha.+.delta..times.sin(.omega..times.t)]}.sup.2(5), 
where, "t" is time. 
".THETA." is given by the following equation (6): 
EQU .THETA.=.pi./2+.beta.(where, .vertline..beta..vertline.&lt;&lt;1)(6) 
Substituting this equation (6) into the equation (5) gives the following 
equation (7): 
EQU I=T.times.I.sub.o 
.times.{sin[.beta.-.alpha.+.delta..times.sin(.omega..times.t)]}.sup.2(7) 
When it is assumed that the angle of rotation attributable to the specimen 
and an amplitude of the modulation are small, that is, 
.vertline..alpha..vertline.&lt;&lt;1, and .delta.&lt;&lt;1, the equation (7) is 
approximated by the following equation (8): 
##EQU1## 
This indicates that the output signal "I" of the photosensor contains 
signal components of angular frequency equals 0 (DC), ".omega." and 
"2.times..omega.", respectively. This is obvious also from FIG. 18. By the 
phase sensitive detection of the value "I" with the vibration-modulated 
signal as a reference signal in the lock-in amplifier, it is possible to 
pick up the component of the angular frequency ".omega.", i.e., the value 
"S" shown by the following equation (9): 
EQU S=T.times.I.sub.o .times.2.times.(.beta.-.alpha.).times..delta.(9) 
This "S" equals to zero only when .beta.=.alpha., i.e., at the extinction 
point. In the process of rotating the analyzer, in other words, sweeping 
".beta.", the value of ".beta." is the angle ".alpha." of rotation when 
"S" becomes zero. 
As described previously, by modulating the direction of polarization, it is 
possible to pick up the signal of the modulated frequency component 
selectively while separating the signal from noises attributable to an 
intensity of the light source, a fluctuation in the power source, a 
radiation and the like, thereby to derive a signal "S" with high S/N 
ratio. Therefore, the extinction point can be determined accurately by 
using this value of "S", and hence highly accurate measurement of the 
angle ".alpha." of rotation is permitted. 
A sample cell for accommodating the specimen used in the above-mentioned 
polarimeter has a pair of transparent light-transmitting windows which 
permit the light to transmit through the inside thereof. Heretofore, the 
sample cells have been configured, for instance, in a box made of glass 
with its top end open. Liquid specimens are introduced into the cells 
through the top open end by the use of a pipette, a syringe and the like. 
The measurement is performed for every sample cells and the replacement of 
the specimen is also performed for every sample cells. Namely, the 
measurement is performed after introducing the specimen into the sample 
cell and arranging the sample cell in an optical system. The specimen is 
therefore required to be replaced together with the sample cell. Further, 
for using the sample cell again, it is required to exhaust the specimen 
from the sample cell taken out from the optical system and to wash the 
sample cell. As described previously, the conventional polarimetry 
consumes much man power. 
In addition, when the specimen is dropped into the sample cell, bubbles are 
liable to be produced in the specimen. Therefore, it has a problem that 
the bubbles existing in the optical path during the measurement 
deteriorates the accuracy of the measurement. 
BRIEF SUMMARY OF THE INVENTION 
An object of the present invention is to provide a sample cell for 
polarimetry which permits easy replacement of the liquid specimen. 
Another object of the present invention is to provide a sample cell capable 
of preventing mixing of bubbles into the liquid specimen and performing 
the polarimetry with high accuracy. 
The present invention provides a sample cell for polarimetry comprising: 
a tubular base member having a cavity which pierces through the member and 
connects a pair of end faces of the base member for accommodating a 
specimen, and a pair of flanges provided around the end faces; 
a pair of light-transmitting windows for sealing a pair of open ends of the 
cavity; and 
a coil configured by winding a wire on the base member between the flanges. 
In a preferred mode of the present invention, the sample cell further 
comprises at least one channel for permitting said cavity to communicate 
with the outside. Herein, the channel includes an inlet channel for 
introducing the specimen into the sample cell, an outlet channel for 
expelling the specimen from the sample cell and a vent hole for permitting 
a flow of air between the inside and the outside of the sample cell at the 
time of introducing and expelling the specimen. However, it is not 
imperative to provide these three kinds of channels, respectively, and a 
channel which can perform a plurality of the above functions may be 
provided instead. For instance, one channel can serve both as the inlet 
channel and the outlet channel. As shown, by providing the channel which 
communicates the cavity with the outside, the replacement of the specimen 
and the washing of the inside of the cell are made easy. Preferably, the 
vent hole is preferentially provided above an optical path of a 
transmitting light, whereas the channel for introducing or expelling the 
specimen or the like is provided above the optical path or at the 
undermost part of the cavity. 
In another preferred mode of the present invention, the top face or bottom 
face of the cavity is inclined with respect to the direction of advance of 
the transmitting light. By virtue of this, it is possible to move the 
bubbles produced in the specimen, thereby to remove them from the 
direction of advance of the transmitting light. 
The present invention further provides a polarimetry comprising the steps 
of: 
arranging a sample cell which comprises a tubular base member having a 
cavity which pierces through the base member and connects a pair of end 
faces of the base member for accommodating a specimen, and a pair of 
flanges provided around the end faces, a pair of light-transmitting 
windows for sealing a pair of open ends of the cavity, and a coil 
configured by winding a wire on the base member between the flanges, while 
inclining an axis of the cavity; 
introducing a liquid specimen to be measured into the cavity; and 
projecting a light upon the light-transmitting window along the axis of the 
cavity. 
In a preferred mode of the present invention, channels for communicating 
the inside of the cavity with the outside thereof are provided at top end 
and bottom end of the cavity of the sample cell, respectively, and the 
specimen is introduced into the cavity through the channel at the bottom 
end. By so designing, bubbles are hardly generated during the introduction 
of the specimen, and it is possible to move the bubbles produced during 
the introduction towards the upper end of the cavity more effectively. 
If a movement of the bubbles is taken into consideration, the same effect 
may also be obtained by inclining the sample cell and projecting the light 
in the horizontal direction. However, in this case, in order to secure an 
optical path length equivalent to the case of inclining the direction of 
projecting light, there is a need for enlarging the diameter or the length 
of the cavity. And hence, a larger amount of specimen is required. By 
contrast to this, according to the polarimetry of the present invention, 
it is possible to make the amount of specimen for one measurement small, 
by inclining also the direction of projecting light. 
While the novel features of the invention are set forth particularly in the 
appended claims, the invention, both as to organization and content, will 
be better understood and appreciated, along with other objects and 
features thereof, from the following detailed description taken in 
conjunction with the drawings.

DETAILED DESCRIPTION OF THE INVENTION 
In the present invention, a tubular sample cell of substantially 
sealed-type having a cavity is used instead of a box-type sample cell 
which has been used in the conventional polarimeter. Both the end faces of 
the cavity is sealed with a light-transmitting material and the specimen 
is contained in the cavity. A coil is provided around the sample cell for 
generating a magnetic field inside the cavity. 
Not being limited to the case of the optical Faraday modulator configured 
with flint glass, an optical Faraday effect attributable to the specimen 
itself is also brought in the case of applying the magnetic field to the 
specimen accommodated in the cell, for rotating the plane of vibration of 
the light transmitting through the inside of the cell. By this phenomenon, 
it is possible to permit the sample cell itself to function as the optical 
Faraday modulator, and hence a simplification and a miniaturization of the 
configuration of the polarimeter becomes possible. 
The optical Faraday effect can be obtained also in the cases of using 
water, chloroform, acetone and the like which are widely used as the 
medium. 
Verdet's constants V of the typical media are shown in TABLE 1. In the 
cases of any media, the Verdet's constant V varies with the kind of the 
medium, the wavelength of light and the temperature. 
TABLE 1 
______________________________________ 
Medium V [minute/A] 
______________________________________ 
Water 1.645 .times. 10.sup.-2 
Chloroform 2.06 .times. 10.sup.-2 
Acetone 1.42 .times. 10.sup.-2 
Quartz 2.091 .times. 10.sup.-2 
Flint glass 4.85 .times. 10.sup.-2 
______________________________________ 
at 20.degree. C. wavelength = 598 nm 
Incidentally, means for applying a magnetic field includes a solenoid coil, 
a permanent magnet or the like which applies a magnetic field along the 
direction of the advance of light. It is possible to modulate the magnetic 
field by modulating the current flown through the solenoid coil or by 
modulating the distance between the permanent magnet and the specimen. By 
winding the coil directly around the sample cell in particular, it is 
possible to combine the sample cell and the means for applying the 
magnetic field into a single unit while making it small and durable at a 
low cost. In a case of providing a pair of flanges on the both ends of the 
sample cell, it is possible to secure a space for retainers for the coil 
and channels for the specimen at these portions. 
Such sample cell uses a base member configured by cutting a block of a 
non-magnetic material such as aluminum. 
When an inlet channel for introducing the specimen into the sample cell, an 
outlet channel for exhausting the specimen from the sample cell and a vent 
hole are provided on the sample cell, it is possible to perform a 
replacement of the specimen and washing of the inside of the cell without 
detaching the sample cell from the optical system. 
When the same sample cell is used for a long term or repeatedly without 
washing or flushing the inside of the cavity, the light transmitting 
window planes of the sample cell are contaminated and an accurate 
measurement becomes impossible. In coping with such contamination, a more 
accurate measurement is made possible by performing a correction in the 
following manner. 
If the contamination is attributable to a substance which does not 
demonstrate an optical activity, the contamination corresponds to a 
substantial decrease in the value "T" in the equation (2) and makes the 
position of the extinct point unclear. Due to this fact, the accuracy of 
the measurement value is deteriorated. In this case, a ratio of the 
variance in the value "I" to the variance in the value ".THETA." in the 
equation (3), or a ratio of the value "S" to the value ".beta." in the 
equation (9) becomes small. It is therefore possible to derive a value due 
to the contamination by measuring a reference specimen whose "T" is known 
and taking the obtained decrease in the value into account. When the value 
due to the contamination exceeds a certain value, washing or replacement 
of the sample cell may well be instructed. In the process, it is not 
imperative to use the reference specimen and the value due to the 
contamination may alternatively be derived from a result of a measurement 
conducted by the use of a specimen whose minimum value of "T" is known. 
By contrast, if the contamination is attributable to a substance having an 
optical activity, the position of the extinction point, i.e., the obtained 
angle of rotation, shifts as much as the displacement in the position. The 
value "I.sub..alpha. " in the equation (3) and the value "S" in the 
equation (9) also vary. The displacement is an angle of rotation due to 
the contamination substance and may simply be added to the angle of 
rotation attributable to the specimen to be determined. For this reason, 
when a measurement has previously been conducted on a reference specimen 
whose angle of rotation is known, and a correction is made on the 
measurement value of the specimen to be determined by the difference 
between the previous measurement value and the known angle of rotation, it 
is possible to ignore an error produced by the contamination substance. 
According to such corrections, it is possible to conduct a measurement with 
high accuracy even if the same sample cell is used repeatedly for a long 
term. It is therefore possible to greatly extend a term set for washing or 
replacement of the sample cell (for instance, until the transmittance of 
the light transmitting window decreases to a specified value), and to make 
the maintenance and management easy. 
In a case of using this polarimeter as a urinalysis equipment for household 
use in particular, its easiness in maintenance and management greatly 
promotes its popularization. 
In the following paragraphs, preferred embodiments of the present invention 
will be described with reference to the drawings. 
EXAMPLE 1 
FIG. 1A and FIG. 1B show a sample cell in accordance with this embodiment. 
The sample cell 1 is obtained in the following manner. 
A base member 2 is obtained by cutting a rectangular solid aluminum block. 
First, by cutting side faces of an aluminum block having a square 
cross-section with a side of 25 mm and a length of 55 mm, a cylindrical 
part with a diameter of 12 mm is formed on the center thereof, while 
leaving untouched parts with a width of 10 mm on the both ends, thereby to 
form flanges 2a and 2b. Then, by forming a cylindrical cavity 3 with a 
diameter of 8 mm which is coaxial with the cylindrical part between the 
both end faces, the base member 2 is obtained. On both open ends of the 
cavity 3, shallow holes with a diameter of 12 mm and a depth of 2.5 mm are 
provided, and glass plates 4 with a diameter of 12 mm and a thickness of 
2.5 mm are tightly fitted into the holes, respectively. The cavity 3 has a 
length i.e., the length of an optical path, of 50 mm and can accommodates 
a specimen of about 2.5 cc therein. 
By winding an enameled wire with a diameter of 0.7 mm around the 
cylindrical part cut between the flanges 2a and 2b of the base member 2 
for 600 turns, a solenoid coil 5 with a length of 35 mm is formed. The 
solenoid coil 5 is for applying a magnetic field to the specimen 
accommodated in the cavity 3. As shown, by providing the flanges 2a and 
2b, the configuration of the solenoid coil 5 is made easy. Threaded holes 
6a and 6b are provided on the flanges 2a and 2b, respectively for fixing 
the sample cell 1 on a polarimeter. The diameter of the threaded holes 6a 
and 6b is 3 mm and the depth thereof is 5 mm. Only after providing the 
flanges 2a and 2b on the base member 2, provision of these threaded holes 
6a and 6b becomes possible. With this measure, installation of the sample 
cell 1 on the polarimeter becomes easy. 
An example of the polarimeter which uses the sample cell 1 is shown in FIG. 
2. A semiconductor laser projector module 8 projects a semiconductor laser 
with a wavelength of 780 nm of an elliptical cross section with a long 
diameter of about 4 mm and a short diameter of about 2 mm in a substantial 
parallel ray as indicated by the dashed line in the figure. The 
semiconductor laser projector module 8 also contains a driving circuit for 
the semiconductor laser which permits the semiconductor laser to oscillate 
continuously. A polarizer 9 transmits only such specified polarized 
component of the projected semiconductor laser that has a plane of 
vibration which is, for instance, parallel to the plane of this paper. An 
analyzer 10 is arranged so as to transmits only such a polarized component 
of the light transmitted through the sample cell 1 that is perpendicular 
to the axis of transmission of the polarizer 9. The photosensor 11 detects 
the light transmitted through the analyzer 10. All of these components are 
fixed on a rail-shaped base plate 7 having a length of 150 mm. 
A current source 12 can supply a sweep current of from -5 A to +5 A to the 
solenoid coil 5 on an instruction signal from a computer 13. The computer 
13 also records and analyzes an output signal from a lock-in amplifier 15. 
A signal generator 14 supplies a modulation signal to the current source 
12 for modulating the current to be supplied to the solenoid coil 5 of the 
sample cell 1. The current source 12 interposes the modulation current due 
to the modulation signal in the sweep current instructed by the computer 
13, and supplies the interposed current to the solenoid coil 5. In this 
embodiment, the current source 12 supplies the modulation current with an 
amplitude=0.02 A to the solenoid coil 5 based on the modulation signal of 
1.3 kHz. The lock-in amplifier 15 performs a phase sensitive detection on 
the output signal of the photosensor 11 by taking the modulation signal of 
the signal generator 14 as a reference signal. The output signal of the 
lock-in amplifier 15 corresponds to the component of the angular frequency 
".omega." of the output signal of the photosensor 15 in the equation (8) 
i.e., the value "S" in the equation (9). Therefore, a time point when "S" 
equals to zero is in the extinction point. 
FIG. 3 shows the output signal of the lock-in amplifier 15, when the 
current to be supplied to the coil 5 is swept in a range between -1.5 A 
and +1.5 A. In FIG. 3, the abscissa indicates the current "J" to be 
supplied to the coil 5 and the ordinate represents the output signal 
(arbitrary value) of the lock-in amplifier 15. 
In the figure, the solid line "a" represents the case wherein pure water 
which does not demonstrate an optical activity is measured as the 
specimen. In this case, when "J" equals to zero i.e., any magnetic field 
is not applied to the pure water as the specimen, an extinction point 
appears. When "J" is allowed to vary, the plane of vibration of the light 
rotates due to the optical Faraday effect and the output signal "S" of the 
lock-in amplifier 15 varies as in the case of varying p in the equation 
(6) i.e., of rotating the analyzer 10. 
In contrast to this, the dashed line "b" in FIG. 3 indicates the case of 
using a sucrose aqueous solution with a concentration of 250 mg/dl at 
20.degree. C. as the specimen. In this case, an extinction point appears 
at J=1.21 A. Namely, the dashed line "b" coincides to a straight line 
obtained by parallelly shifting the solid line "a" along the abscissa by 
+1.21 A. The width of this shift of the extinction point corresponds to 
the angle of rotation due to the specimen. 
In the following description, the above-mentioned fact will be confirmed 
quantitatively. 
On the basis of the equation (1), the angle of rotation ".alpha." 
attributable to the sucrose in the specimen is: 
EQU .alpha.=[.alpha.]/10000.times.0.05.times.250.apprxeq.0.0831[degree]. 
Next, when an angle of rotation in the direction of polarization due to the 
optical Faraday effect "a" is calculated by the use of the equation (4), 
the following result is obtained. 
Based on the characteristics of the solenoid coil 5, it is derived that the 
magnetic field H=6.05.times.103 A/m under the condition of J=1.21 A. From 
this value and the Verdet's constant "V" of water shown in TABLE 1, 
EQU a=1.645.times.10.sup.-2 .times.0.05.times.10.sup.4 
.times.0.05.apprxeq.4.976[minute]=0.083[degree] 
is derived. 
As described above, it is confirmed that the angle of rotation due to the 
specimen coincides with the angle of rotation due to the optical Faraday 
effect. 
In a manner similar to the above, the angles of rotation are additionally 
measured at 20.degree. C. by using sucrose aqueous solutions with 
concentrations of 50, 100, 150 and 250 mg/dl, respectively. The results 
thereof are shown in FIG. 4. In FIG. 4, the abscissa represents the 
concentration of the sucrose and the ordinate represents the current "J" 
for reaching the extinction point. As seen from FIG. 4, it is recognized 
that the one is proportional to the other. 
Although such a case where the extinction point exists in the range of 
sweeping the magnetic field is shown in this embodiment, the angle of 
rotation can also be calculated, even in another case where no extinction 
point exists in the range of sweeping, by extrapolating the characteristic 
in the range, because the output signal "S" of the lock-in amplifier 15 
varies linearly with respect to the magnetic field i.e., the current "J", 
as illustrated by FIG. 3 and indicated by the equation (9). In addition, 
since "J" and "S" are in a proportional relationship, it is not imperative 
to sweep the magnetic field continuously but the angle of rotation can 
instead be calculated by interpolating or extrapolating the results of the 
measurements on at least two points. By this procedure, it is also 
possible to shorten the time for conducting the measurement. 
Next, a similar measurement is conducted on pure water as the specimen by 
using a sample cell whose transmitting windows are contaminated as a 
result of being stood for a long term without washing. In that case, an 
extinction point appears at J=0.02 A. From this value, the angle of 
rotation "d" attributable to the contaminating substance on the light 
transmitting windows of the sample cell is derived on the basis of the 
equation (4) and TABLE 1 as: 
EQU d=1.645.times.10.sup.-2 .times.10.sup.2 
.times.0.05.apprxeq.0.082[minute].apprxeq.1.4.times.10.sup.-3 [degree]. 
In a case of measuring the angle of rotation attributable to a fresh 
specimen by the use of this sample cell, an accurate angle of rotation can 
be obtained by correcting the measurement value by subtracting "d" from 
it. Namely, even in such a case of using the same sample cell repeatedly 
for a long term, it is possible to perform a measurement with high 
accuracy by correcting the measurement value of the specimen with a 
measurement value of a reference sample whose angle of rotation is known. 
By this procedure, it is possible to extend the time period set for 
washing or replacement of the sample cell until the transmittance of the 
light transmitting windows decreases to a specified value. 
Further, by sweeping the magnetic field i.e., varying the magnetic field 
from a specified intensity to another specified intensity (including a 
change of polarity in the magnetic field), it is possible to continuously 
rotate the plane of vibration of light. By this procedure, it is possible 
to obtain an effect which is the same as the rotation of the analyzer. 
Therefore, by placing the polarizer and the analyzer in an orthogonal 
Nicol's state, in other words, maintaining the relative angle formed 
between the transmission axes of the both at 90 degrees, it is possible to 
negate the optical rotation attributable to the optical active substance 
in the specimen by sweeping the intensity of the magnetic field generated 
in the specimen, thereby to calculate the angle of rotation based on the 
intensity of the magnetic field at that time. 
In other words, it is possible to measure the angle of rotation by reading 
out the current value supplied to the coil at an appearance of an 
extinction point, and by converting it into the intensity of the magnetic 
field and further into the angle of rotation attributable to the optical 
Faraday effect. According to this procedure, the angle of rotation can be 
derived based substantially on the intensity of the magnetic field at the 
time when the angle of rotation produced by the optical active substance 
in the specimen coincides to the angle of rotation in the plane of 
vibration due to the optical Faraday effect. 
As described above, according to this embodiment, it is possible to apply a 
magnetic field to the specimen by winding a coil directly around the 
sample cell. 
EXAMPLE 2 
A sample cell in accordance with this embodiment is shown by FIG. 5A and 
FIG. 5B. 
The sample cell 22 has the same structure as that used in EXAMPLE 1. An 
inlet/outlet channel 23 with a diameter of 6 mm is however provided on the 
sample cell 22, for communicating the inside of the cavity 3 with the 
outside. The inlet/outlet channel 23 is arranged above the cavity 3, in 
particular, so that it is positioned at an upper side of the optical path 
for the projected light. 
The specimen is introduced into the cavity 3 through the inlet/outlet 
channel 23. At the time of the introduction, air inside the sample cell 22 
is expelled therefrom through the inlet/outlet channel 23 to the outside. 
Herein, since the inlet/outlet channel 23 is formed above the optical 
path, no air remains in the optical path of light after the introduction 
of the specimen. Therefore, an accurate measurement is made possible. 
The specimen is expelled therefrom by being suctioned through the 
inlet/outlet channel 23. At the time of washing the cavity 3 of the sample 
cell 22, water or a cleaning solution is introduced into the cavity 3 
through the inlet/outlet channel 23. 
By providing the inlet/outlet channel 23 on the sample cell 22 as in this 
embodiment, replacement of the specimen or washing of the sample cell 
becomes easy. 
EXAMPLE 3 
A sample cell in accordance with this embodiment is shown by FIG. 6A and 
FIG. 6B. 
The sample cell 24 of this embodiment is obtained in the following manner. 
First, by cutting side faces of an aluminum block having a square 
cross-section with a side of 25 mm and a length of 55 mm, a cylindrical 
part with a diameter of 17 mm is formed on the center thereof, while 
leaving untouched parts with a width of 10 mm on its both ends, 
respectively, thereby to form flanges 25a and 25b. Then, a cavity 26 
having a rectangular cross-section is formed between the both end faces. 
The cross-section of one open end of the cavity 26 is a rectangle of 8 
mm.times.13 mm and the cross-section of the other open end is a square of 
8 mm.times.8 mm. The top face of the cavity 26 has an inclination of about 
5.7 degrees (tan.sup.-1 (5/50)) between the both open ends. On the wider 
open end of the cavity 26, a circular hole with a diameter of 22 mm and a 
depth of 2.5 mm is provided, and a glass plate 27a with a diameter of 22 
mm and a thickness of 2.5 mm is tightly fitted into the hole. On the 
narrower open end of the cavity 26, a circular hole with a diameter of 12 
mm and a depth of 2.5 mm is provided, and a glass plate 27b with a 
diameter of 12 mm and a thickness of 2.5 mm is tightly fitted into the 
hole. 
On the upper end of the cavity 26 i.e., the wider open end side of the 
inclined top face of the cavity 26, an inlet/outlet channel 28 having a 
circular cross section with a diameter of 6 mm is provided. 
The length of the optical path of the sample cell 24 thus obtained is 50 mm 
and the cavity 26 thereof can accommodate a specimen of about 4.2 cc. 
The specimen is introduced into the cavity 26 through the inlet/outlet 
channel 28. At the time of the introduction, air inside the cavity 26 is 
expelled therefrom through the inlet/outlet channel 28 to the outside. 
Herein, since the inlet/outlet channel 28 is provided above an optical 
path, no air remains in the optical path after the introduction of the 
specimen. 
In addition, since the top face of the cavity 26 is inclined and the 
inlet/outlet channel 28 is provided at the uppermost part thereof, bubbles 
produced during the introduction of the specimen, after floating 
themselves upwards, move along the inclined top face up to the 
inlet/outlet channel 28. Namely, it is possible to prevent the disturbance 
on a transmitting light by the bubbles mixed with the specimen in the 
cavity 26. Therefore, a measurement on the angle of rotation can be 
conducted more accurately as compared with the sample cell 22 of EXAMPLE 
2. The specimen introduced into the cavity 26 is expelled therefrom by 
being suctioned through the inlet/outlet channel 28. At the time of 
washing the cavity 26, water or a cleaning solution is introduced therein 
through the inlet/outlet channel 28. 
EXAMPLE 4 
A sample cell in accordance with this embodiment is shown by FIG. 7A and 
FIG. 7B. 
The sample cell 30 has a structure similar to the sample cell 24 used in 
EXAMPLE 3. However, the sample cell 30 has a vent hole 31 having a 
circular cross-section with a diameter of 1.0 mm provided on the uppermost 
part i.e., the wider open end side of the inclined top face of the cavity 
26 for communicating the inside with the outside, instead of the 
inlet/outlet channel 28. On the bottom face at the narrower open end side 
i.e., the undermost part of the cavity 26, an inlet/outlet channel 32 of a 
circular cross-section with a diameter of 2.5 mm is arranged. The specimen 
is introduced into the cavity 26 through the inlet/outlet channel 32. At 
the introduction, air inside the cavity 26 is expelled therefrom through 
the vent hole 31. After the measurement, the specimen is expelled 
therefrom through the inlet/outlet channel 32. At that time, air flows 
into the cavity 26 through the vent hole 31. At the time of washing the 
cavity 26, water or a cleaning solution is introduced and expelled through 
the inlet/outlet channel 32. 
In the case of the sample cell of this embodiment, by virtue of providing 
the inlet/outlet channel 32 at the undermost part of the cavity 26, the 
expelling of the specimen becomes more easy as compared with the sample 
cell 24 of EXAMPLE 3. In addition, it is possible to suppress a mixing the 
specimen introduced into the cavity 26 with air, and to greatly reduce the 
amount of the bubbles produced during the introduction of the specimen. 
EXAMPLE 5 
A sample cell in accordance with this embodiment is shown by FIG. 8A and 
FIG. 8B. 
The sample cell 34 uses a base member 35 configured by working on an 
aluminum block similar to those in the above-mentioned embodiments, in 
which an axis of the cylindrical cavity 36 is inclined. The sample cell 34 
is produced in the following manner. 
First, by cutting side faces of an aluminum block, a cylindrical part with 
a diameter of 17 mm is formed on the center thereof, while leaving 
untouched parts with a the width of 10 mm on the both ends, thereby to 
form flanges 35a and 35b. Then, a cylindrical cavity 36 having a diameter 
of 12 mm and an axis inclined by about 5.7 degrees (tan.sup.-1 (5/50)) 
with respect to the axis of the cylindrical part is provided between the 
both end faces. On both open ends of the cavity 36, holes with a diameter 
of 22 mm and a depth of 2.5 mm are provided, and glass plates 37a and 37b 
with a diameter of 22 mm and a thickness of 2.5 mm are tightly fitted into 
the holes, respectively. The cavity 36 has a length i.e., length of the 
optical path of 50 mm and can contain the specimen of about 5.7 cc. 
The sample cell 34 has a vent hole 38 having a circular cross-section with 
a diameter of 1.0 mm provided on the uppermost part of the cavity 36 for 
communicating the inside with the outside. In addition, an inlet/outlet 
channel 39 having a circular cross-section with a diameter of 2.5 mm is 
provided at the undermost part of the cavity 36. 
By virtue of providing an inclination on the bottom face of the cavity 36 
for containing the specimen as in the sample cell 34 of this embodiment, 
the expelling of the specimen becomes more easy as compared with the 
sample cell 30 of EXAMPLE 4. 
EXAMPLE 6 
A sample cell in accordance with this embodiment is shown by FIG. 9A and 
FIG. 9B. 
The sample cell 41 has a structure similar to the sample cell 24 used in 
EXAMPLE 3. The sample cell 41 however has an outlet/vent hole 42 of a 
circular cross-section with a diameter of 2.5 mm provided, instead of the 
inlet/outlet channel 28. In addition, at the narrower open end side of the 
bottom face of the cavity 26, an inlet channel 43 of a circular 
cross-section with a diameter of 2.5 mm is provided. 
At the time of replacing the specimen, a fresh specimen is introduced into 
the cavity 26 through the inlet channel 43, and the used specimen is 
expelled therefrom by being pushed out through the outlet/vent hole 42. At 
the time of washing the cavity 26, water or a cleaning solution is 
continuously introduced through the inlet channel 43 and expelled through 
the outlet/vent hole 42. 
EXAMPLE 7 
A sample cell in accordance with this embodiment is shown by FIG. 10A and 
FIG. 10B. 
The sample cell 45 has a structure similar to the sample cell 34 used in 
Embodiment 5. However, the sample cell 45 has an inlet/vent hole 46 of a 
circular cross-section with a diameter of 2.5 mm provided, instead of the 
vent hole 38. An outlet channel 47 having a similar configuration to that 
of the inlet/outlet channel 39 is used exclusively for expelling the 
specimen from the cavity 36. The specimen is introduced into the cavity 
through the inlet/vent hole 46. 
At the same time, air inside the cavity 36 is expelled therefrom through 
the inlet/vent hole 46. At the time of replacing the specimen, a fresh 
specimen to be determined is introduced into the cavity 36 through the 
inlet/vent hole 46, while the already-examined specimen is remaining in 
the cavity 36, and the examined specimen which had previously been 
introduced into the cavity 36 is expelled through the outlet channel 47. 
At the time of washing the cavity 36, water or a cleaning solution is 
introduced therein through the inlet/vent hole 46 and expelled through the 
outlet channel 47. 
As mentioned above, by designing the base member so as to introduce the 
fresh specimen into the cavity from the top thereof, and to expel the 
examined specimen in the cavity from the bottom thereof, both the 
specimens are rendered hardly liable to mix with each other, and the 
replacement of the specimen in the cavity becomes easy. For the same 
reason, the washing of the cavity is made easy. 
EXAMPLE 8 
A sample cell in accordance with this embodiment is shown by FIG. 11A and 
FIG. 11B. 
The sample cell 49 has a structure similar to the sample cell 34 used in 
EXAMPLE 5. However, the sample cell 49 has an inlet channel 51 is 
additionally provided on the bottom of the cavity 36 at a position 
opposite to the vent hole 38. In addition, an outlet channel 50 having a 
similar configuration to that of the inlet/outlet channel 39 is used 
exclusively for expelling the specimen. 
A specimen to be examined is supplied to the cavity 36 through the inlet 
channel 51. Air inside the cavity 36 is expelled therefrom through the 
vent hole 38. As shown, by the virtue of inclining the axis of the 
cylindrical cavity 36, even in a case of involving the bubbles in the 
cavity 36, the bubbles do not interfere with the transmitting light 
because the bubbles move along the wall of the cavity 36. 
In addition, by providing the inlet channel 51 on the bottom, it is 
possible to suppress a mixing of the air inside the cavity 36 with the 
specimen at the time of introducing the specimen, and to greatly reduce 
the bubbling. The specimen in the cavity 36 is expelled therefrom through 
the outlet channel 50. At that time, air is flown into the cavity 36 
through the vent hole 38. By virtue of inclining the axis of the 
cylindrical cavity 36, the expelling is easy. At the time of replacing the 
specimen, a fresh specimen is introduced into the cavity 36 through the 
inlet channel 51, and the examined specimen which had previously been 
introduced into the cavity 36 is expelled through the outlet channel 50 by 
being pushed out. At the time of washing the cavity 36, water or a 
cleaning solution is introduced therein through the inlet channel 51 and 
expelled therefrom through the outlet channel 50. 
EXAMPLE 9 
A sample cell in accordance with this embodiment is shown by FIG. 12A and 
FIG. 12B. 
The sample cell 53 has the same structure as that used in EXAMPLE 1. 
However, a vent hole 54a having a circular cross-section with a diameter 
of 1.0 mm is provided on the top of the cavity 3 at the one open end side. 
On the top of the cavity 3 at the other open end side, another vent hole 
54b is provided. In addition, on the bottom of the cavity at its both open 
ends side, an inlet channel 55 having a circular cross-section with a 
diameter of 2.5 mm and an outlet channel 56 having a circular 
cross-section with a diameter of 2.5 mm are provided, respectively. 
By virtue of providing the inlet channel 55 on the bottom as shown, it is 
possible to greatly reduce the bubbling at the introduction of specimen. 
When the examined specimen is expelled therefrom through the outlet 
channel 56, air is flown into the cavity 3 through the vent holes 54a and 
54b. 
At the time of replacing the specimen, a fresh specimen is introduced 
through the inlet channel 55 and the examined specimen is expelled 
therefrom by being pushed out through the outlet channel 56. At the time 
of washing the cavity 3, water or cleaning solution is introduced therein 
through the inlet channel 55. 
EXAMPLE 10 
By virtue of inclining the top or bottom face of the cavity in the sample 
cell or inclining the axis of the cylindrical cavity as mentioned in the 
foregoing embodiments, it is possible to suppress the bubbling at the 
introduction of specimen. However, the working on the cavity to have such 
peculiar configurations represents a low productivity. In addition, the 
cavity of the peculiar configuration needs a large amount of specimen. For 
instance, the sample cell 34 of Embodiment 5 shown in FIG. 8A and FIG. 8B 
requires a larger diameter of the cylindrical cavity 36 for securing an 
equivalent optical path length as that of the sample cell 1 shown in FIG. 
1A and FIG. 1B. 
Under the circumstances, a method of performing polarimetry on a smaller 
amount of the specimen by the use of a sample cell similar to the sample 
cell 1 of EXAMPLE 1 which is excellent in its workability will be 
described in this embodiment. 
The sample cell 61 shown in FIG. 13 has a structure similar to the sample 
cell 1 of EXAMPLE 1. 
On one open end of the cavity 3 of the sample cell 61, an inlet/outlet 
channel 62 with a diameter of 1.0 mm which communicates with the outer 
side wall is arranged. On the other open end of the cavity 3 and at a 
position axially-rotated by 180 degree with respect to the position where 
the inlet/outlet channel 62 is arranged, a vent hole 63 with the same 
diameter of 1.0 mm which also communicates with the outer side wall is 
arranged. 
The sample cell 61 is used in a manner as shown, for instance, in FIG. 14. 
As shown, by using a polarimeter similar to that in EXAMPLE 1, the axis of 
the sample cell i.e., the direction of the advance of the transmitting 
light is inclined at an angle, for example, 45 degrees. 
The sample cell 61 is arranged so that the inlet/outlet channel 62 is 
placed at its lower end and its vent hole 63 is placed at its upper end. 
At the time of introducing a specimen to be examined, the specimen is 
introduced into the sample cell 61 through the inlet/outlet channel 62 by 
using a syringe, a pump or the like. At that time, since air inside the 
cavity 3 is expelled through the vent hole 63, it is possible to introduce 
a liquid specimen smoothly. Herein, since the top face of the cavity 3 is 
inclined, bubbles are hard to generate during the introduction of the 
specimen, and since the generated bubbles move, after floating themselves 
upwards in the specimen, towards the upper end of the cavity along the top 
face of the cavity 3, the bubbles do not interfere with the transmission 
of the projected light. 
When the specimen is replaced after one measurement, the examined specimen 
in the cavity 3 is expelled therefrom through the inlet/outlet channel 62. 
In a case wherein the amount of specimen for the measurement is larger than 
the volume of the cavity, a fresh specimen may be introduced through the 
inlet/outlet channel 62 in a state where the specimen which had previously 
been measured remains in the cavity. 
At the time of washing the sample cell 61, water or a cleaning solution is 
likewise introduced into the cavity through the inlet/outlet channel 62. 
By introducing a larger amount of cleaning solution or the like than the 
volume of the cavity 3 through the inlet/outlet channel 62, thereby to 
supply the cleaning solution continuously to the cavity 3 and to expel it 
through the vent channel 63, it becomes possible to wash the sample cell 
61 effectively. 
In this embodiment, although the light is illustrated to be projected 
upwards from the bottom, a similar technical advantage will be obtained by 
projecting the light downwards from the top. 
With respect to the suppression of the bubbling in the specimen, a similar 
technical advantage is obtained in the case of measuring by using the 
sample cell 34 of EXAMPLE 5 and projecting the light in the horizontal 
direction. However, in order to prevent the refraction of the incident 
light on the specimen, the glass plate 37a for the light transmitting 
plane should be placed in perpendicular to the incident direction of the 
light. Therefore, in the case of inclining the axis of the cavity 36 of 
the sample cell 34, there is a need for elongating the length of the 
cavity 36 for securing an optical path length as that of the sample cell 
61 used in this embodiment. 
In addition, in a case of inclining the axis of the cavity 36 at a larger 
angle, there is a need for enlarging the cross-sectional area of the 
cavity 36. Therefore, a larger amount of the specimen is required as 
compared with the sample cell 61 of this embodiment. Further, since there 
is another need for inclining the normal of the transmitting plane with 
respect to the axis of the cavity 36, the workability of the sample cell 
is poor. 
In a case of applying a magnetic field to the specimen in the sample cell 
34 by the coil as in the case of the sample cell 61 of this embodiment, 
there is a need for increasing the turn number of the coil 5 or the 
current value to be supplied to the coil 5 for generating a magnetic field 
equivalent to that for the sample cell 61 because the sample cell 34 has a 
cavity 26 of larger diameter or length. If the turn number of the coil 5 
is increased, a heat generated in the coil 5 increases. When the current 
value to be supplied to the coil 5 is increased, the heat generated in the 
coil 5 increases and the preciseness in the measurement is made inferior. 
As described previously, according to the present invention, the 
measurement on the optical characteristic of the specimen can be conducted 
with a high operability because there is no requirement of detachment of 
sample cell at the measurement of the optical characteristic. In addition, 
since it is possible to suppress the adverse effect of the bubbles 
produced during the introduction of the specimen, a polarimetry with high 
precision is made possible. Further, it is possible to reduce the amount 
required for the measurement. 
It is understood that various other modifications will be apparent to and 
can be readily made by those skilled in the art without departing from the 
scope and spirit of this invention. Accordingly, it is not intended that 
the scope of the claims appended hereto be limited to the description as 
set forth herein, but rather that the claims be construed as encompassing 
all the features of patentable novelty that reside in the present 
invention, including all features that would be treated as equivalents 
thereof by those skilled in the art to which this invention pertains.