DD270448A3 - Method for calibrating temperature measuring devices - Google Patents

Abstract

The aim of the invention is the calibration of temperature measuring devices, in particular microscopic heating and cooling devices, primarily for biology and medicine, whereby the systematic temperature measurement error of the actual temperature sensor can be determined depending on the object temperature in the usable temperature range. According to the invention, a concentration series is formed from crystalline liquid test substances having different Klaertemperaturen characterizing the transition from the anisotropic to the isotropic state. In particular, mixtures according to the invention of 4-n-methoxybenzoic acid (4-n-pentylphenyl ester) and 4-n-hexylbenzoic acid (4-n-propylphenyl ester) are used.

Description

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Field of application of the invention

The invention relates to a method for calibrating temperature measuring devices on heating and cooling devices, primarily for microscopes.

Characteristic of the known technical solutions

Known heating and cooling devices on microscopes are generally equipped with a temperature Meßrnittel (expansion thermometer, resistance thermometer, thermocouple). Since microscopic objects have only very small heat capacity because of their very small mass and size, the approach of the temperature sensor, which is desirable in itself, leads to the respectively observed object location. U. significant falsification of Tsmperaturfeldes in the object space. Therefore, one arranges the temperature sensor at some distance from the observed object field and thus accepts a generally temperature-dependent, systematic measurement error of the temperature display in purchasing. Determination of size and temperature dependence of this measurement error is carried out in a known manner so that as a microscopic test preparation pure crystalline or liquid substances or mixtures of such substances (test substances) is used, in which observable in the temperature range usable with the heating and cooling device transformations (melting, solidification , Modification changes, etc.). If one uses a series of such test substances whose transformation temperatures are distributed as uniformly as possible over the usable temperature range, the systematic measurement error of the temperature measuring means used can be determined as a function of the object temperature. When determining the systematic measurement error, a prescribed working regime must always be observed. (L. Kofier, A. Kofier: Micromethods for the Identification of Organic Substances and Mixtures., Universitätsverlag Wagner GmbH, Innsbruck 1948).

With heating and cooling devices for microscopic studies in biology and medicine is generally worked at Temperaturerf, which differ only relatively little from the human temperature + 37 ° C. The use of test substances of the type described is questionable, since depending on the geographical location of the Einwirkortes the microscopic device, the critical transformation temperatures - especially melting and solidification temperatures - of the test substances used more or less often exceeded or fallen below, thereby in Veriauf the time z. B. initially fine-crystalline-present test substances melt together. Subsequent comminution can easily lead to contamination or other influences on the test sub-assemblies, which make their use for measuring error detection practically impossible. (B.Hahne, R. Herrling, M. Neupert, HH Seyfarth: The heating and cooling table -20 ... + 80 ⁰ C and its application Jenaer Rundschau 17 / 1972-2 / 75-83).

Furthermore, a method is known in which the transition temperature from the anisotropic state to the isotropic state is used for substances with liquid crystal structure in order to characterize temperature fields occurring on integrated circuits during operation by determining isotherms.

It has already been proposed. Liquid crystals, which show typical optical changes at the phase transition temperatures, to determine isotherms on solid surfaces. (GB Patent 1,442,802: F.N. Sinnadurai, C.E. Stephens, A.J. Melia / Post Office, London, Temperature Measurement Using Liquid Crystals IPK-GOIK 11 / 12.9, 2. 73/14, 7. 76). This process has the disadvantage that the liquid crystal substances to be used have fixed transformation temperatures which can not be changed by the proposed process. However, it is often necessary to measure a specific temperature determined by the problem to be solved.

It will '·. The literature also describes a method in which the clearing temperature of a substance with liquid crystal structure for Terr.peraturermittlung is used, wherein the clearing temperature is variable by the addition of a solvent. (Gti-Paientschrift 2078954: HJ Coles / The Victoria University of Manchester: A liquid crystal temperature indicator. IPKG01K '· 1 / 16.1. 7. 80 / 13.1. 82). This method has the disadvantage that the solvent evaporates easily and thus changes the transition temperature, which can lead to considerable measurement errors.

Object of the invention

The aim of the invention is the calibration of temperature measuring devices, especially on microscopic heating and cooling devices primarily for biology and medicine, whereby the systematic Temperaturmeßfehler the actual temperature sensor (extension thermometer, resistance thermometer, thermocouple) can be determined in dependence on the object temperature in the usable temperature range.

Explanation of the essence of the invention

The object of the invention is the use of substances which are stable, colorless and non-hygroscopic, have no sublimation phenomena and have transition temperatures without hysteresis effects, ie test substances for calibrating microscopic heating and cooling devices.

It has been found that zv. Calibration of temperature measuring for heating and cooling devices, in particular for microscopes, chemical compounds of a series of liquid-crystalline substances and different, the transition from anisotropic to isotropic state characterizing clearing temperatures are excellent as test substances.

In particular, mixtures of a concentration series between 4-methoxybenzoic acid (4-n-pentyphenylester) and 4-n-hexylbenzoic acid (4-n-propyiphenylester) may be used as the test substance. It is advantageous to observe the test substances at the clearing point in polarized light between crossed polar. These test substances are sta't. Of the usual objects heated and cooled to determine the systematic error of the display of the actual Temperaturmeßmittels (expansion or resistance thermometer, thermocouple) in its size and temperature dependence.

A> isfiihrungsbeispiele

example 1

The substances listed below have clearing temperatures which cover a wide temperature range and are suitable for use according to the invention in microscopic heating and cooling devices.

It means:

K = crystalline - solid

N = nematic state

Sc = smectic C phase

Is = isotropic - liquid

2) CHpO- / OE-COO- / O) -OcBL,

3) C ₅ H ₁₁ O- (O) -CJOO- (0) -Cr

4) CH ₀ O- <V> -COO- <V

5) O ₆ H ₁₃ O- (Oy-COO- (O) -OC ₉ H ₁₇

6) O ₂ H ₅ O- (θ) -COO- (θ) -O-CC ₄ Hq

7) C ₃ H ₇ O- (θ) -N = N- (o -OC ₃ H ₇

8) CH ₃ O- (θ) -N = N- <V) -OCH ₃

9) C ₈ H ₁₇ O-COO- (θ) -COO- (θ) -OOC- (θ) -

Cl

K 9,3 N 15 Is

K 29 N 42 Is K 43 N% Is K 55 N? 8.5 Is K 51 N 89 Is K 95.5 N106.5Is

K118,2N135,2Is

K 76 H 157

10) O ₂ HcO- (O) -NaN- (O) - (XJ ₂ H ₅ K136,6N167,5Is

11) O ₂ H ₅ - (S) -000- (O) -000- (O) -OC ₇ H ₁₅ K62 (Sc41.5) N 183Is

12) o ₅ h ₁₁ 000- (ö) -000- (ö) -000- (o) -oo-o ₅ h ₁₁

Oh T

E 100 N 209 Is

13) 0 ^ H ₉ O- (O) -000- (O) -OOO- (O) -OC ₅ H ₁₁ K 140 N 229 Is

14) C ^ H ₁₁ 000- (O) -000- (O) -000- (θ)

K 155 Π 246 Is

Depending on their composition, the mixtures of each two adjacent substances of this table permit sweeping of all temperatures between the clearing points (n / ls) of the pure substances.

Example 2 The substances

4-n-Methoxybenzoic acid (4-n-pentylphenyl ester) (A)

GH ₃ O - <O> - COO -

and 4-n-hexylbenzoic acid (4-n-propylphenyl ester) (B)

° 6 ^H 13 ""

Form between the solid and the isotropic-liquid state of a nematic crystalline-liquid phase. The table below gives the transition temperatures of the transition nematic to isotropic-liquid (clearing temperatures) for both the equiax components and some selected mixtures.

Mole fraction of component A clearing temperature ( ⁰ C)

1.0 42.0-42.5

0.9 37.7-38.0

0.8 33.9-34.1

0.7 29.7-30.0

0.6 26.9-27.1

C.5 23,2-23,4

0.42 20.5-21.0

0.30 17.0-17.4

0.15 12.0-12.4

For mixtures with arbitrary concentrations, the clarification temperature of Fig. 1 can be read off.

Claims (3)

1. A method for calibrating temperature measuring devices to heating and cooling devices, in particular for microscopes, characterized in that a series of concentrations is formed from crystalline liquid test substances with different, the transition from anisotropic to isotropic state characterizing clearing temperatures. 2. The method according to claim ^, characterized in that the concentration series of 4-methoxybenzoic acid (4-n-pentylphenyl ester) and 4-n-hexylbenzoic acid (4-n-propylphenylester) is formed. 3. The method according to claim 1 to 3, characterized in that the illumination of the microscope is carried out with linearly polarized light, wherein polarizer and analyzer are used in the crossed position of the vibration directions.