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EP-4343293-B1 - SAMPLE HOLDER FOR HOLDING A PLATE-SHAPED SAMPLE IN A LASER/LIGHT FLASH ANALYSIS

EP4343293B1EP 4343293 B1EP4343293 B1EP 4343293B1EP-4343293-B1

Inventors

  • Lauerer, Alexander
  • Lunev, Artem
  • LAUTERBACH, STEFAN
  • SHINODA, YOSHIO

Dates

Publication Date
20260506
Application Date
20220926

Claims (10)

  1. A sample holder (1) for holding a plate-shaped sample during a laser/light flash analysis of the sample, wherein the sample has a first side and a second side opposite to the first side, and wherein the laser/light flash analysis comprises - irradiating two first rectangular areas on the first side of the sample with an electromagnetic excitation pulse from a radiation source, - detecting thermal radiation emitted from a second rectangular area on the second side of the sample as a result of the excitation pulse by means of a radiation detector, wherein a longitudinal axis of the second rectangular area is parallel to a longitudinal axis of the two first rectangular areas and offset orthogonally to the direction of the longitudinal axis of the two first rectangular areas, wherein the sample holder (1) comprises - a first mask (10) provided to face the radiation source during the laser/light flash analysis and adapted to define two first slits (12-1, 12-2) corresponding to the two first rectangular areas on the first side of the sample, - a second mask (20) provided to face the radiation detector during the laser/light flash analysis and adapted to define a second slit (22) corresponding to the second rectangular area on the second side of the sample, and - a receiving space (30) provided between the first mask (10) and the second mask (20) adapted to receive the sample with the first side facing the first mask (10) and the second side facing the second mask (20), characterized in that the sample holder (1) is adapted to enable - a change of a length and a width of the two first slits (12-1, 12-2) defined by the first mask (10) to correspondingly change a length and a width of the two first rectangular areas on the first side of the sample, wherein the first mask (10) comprises - a first frame member (11) having at least one through opening (13-1, 13-2) formed therein, - a first pair of masking panels (14-1, 14-2) supported oppositely to each other on the first frame member (11) and each slidably adjustable in a direction of a longitudinal axis of the two first slits (12-1, 12-2) such that the length of the two first slits (12-1, 12-2) is adjustable by sliding these masking panels (14-1, 14-2), wherein these masking panels (14-1, 14-2) are guided in corresponding recesses on a flat side of the first frame member (11), - a second pair of masking panels (16-1, 16-2) each supported oppositely to each other on the first frame member (11) and each slidably adjustable orthogonally to the direction of the longitudinal axis of the two first slits (12-1, 12-2) such that the width of the two first slits (12-1, 12-2) is adjustable by sliding these masking panels (16-1, 16-2), wherein these masking panels (16-1, 16-2) are guided in corresponding recesses on said flat side of the first frame member (11), and - a central masking panel (15) interchangeably supported on the first frame member (11) such that a distance between the two first slits (12-1, 12-2) is changeable by interchanging the central masking panel (15).
  2. The sample holder (1) according to claim 1, wherein the central masking panel (15) is interchangeably held form-fittingly in a corresponding recess on said flat side of the first frame member (11).
  3. The sample holder (1) according to claim 2, wherein the central masking panel (15), the first pair of masking panels (14-1, 14-2) and the second pair of masking panels (16-1, 16-2) each are arranged at their own respective levels on said flat side, and wherein the vertical distance between two adjacent levels corresponds to the respective thickness of the respective panel or panels (15; 14-1, 14-2; 16-1, 16-2), such that in an assembled state of the sample holder (1), the masking panels (15; 14-1, 14-2; 16-1, 16-2) arranged on adjacent levels are in contact with each other.
  4. The sample holder (1) according to any of claims 1 to 3, wherein the sample holder (1) is further adapted to enable - a change of a length and/or a width of the second slit (22) defined by the second mask (20) to correspondingly change a length and/or a width of the second rectangular area on the second side of the sample, wherein the second mask (20) comprises a second frame member (21) having a central through opening (23) formed therein, and at least one masking panel (24-1, 24-2, 26-1, 26-2) interchangeably and/or slidably adjustable supported on the second frame member (21) such that the length and/or the width of an aperture of said through opening (23) representing the second slit (22) is changeable by interchanging and/or sliding said at least one masking panel (24-1, 24-2, 26-1, 26-2).
  5. The sample holder (1) according to claim 4, wherein the second mask (20) comprises - a first pair of masking panels (24-1, 24-2) supported oppositely to each other on the second frame member (21) and each slidably adjustable in a direction of a longitudinal axis of the second slit (22) such that the length of the second slit (22) is adjustable by sliding at least one of these masking panels (24-1, 24-2), - a second pair of masking panels (26-1, 26-2) each supported oppositely to each other on the second frame member (21) and each slidably adjustable orthogonally to the direction of the longitudinal axis of the second slit (22) such that the width of the second slit (22) is adjustable by sliding at least one of these masking panels (26-1, 26-2).
  6. The sample holder (1) according to claim 5, wherein the second frame member (21) has a pair of grooves (27) opposing each other in the direction orthogonal to the sliding direction of one (24-1, 24-2) of the first and second pairs of masking panels (24-1, 24-2, 26-1, 26-2) and each running in the direction of this sliding direction, wherein rims of the masking panels of the respective pair of masking panels (24-1, 24-2) opposing each other in the direction orthogonal to the sliding direction engage into the grooves (27) so as to provide a linear guide for sliding of the respective pair of masking panels (24-1, 24-2).
  7. The sample holder (1) according to claim 6, wherein the masking panels of the other one (26-1, 26-2) of the first and second pairs of masking panels (24-1, 24-2, 26-1, 26-2) each are slidably adjustably clamped between surfaces of the second frame member (21), on the one hand, and the masking panels (24-1, 24-2) guided by the pair of grooves (27), on the other hand.
  8. The sample holder (1) according to any of claims 4 to 7, further comprising - a third frame member (41) having a central through opening (23) formed therein and constituting the receiving space (30) for accommodating the sample, wherein the third frame member (41) is sandwiched between the first frame member (11) and the second frame member (21).
  9. The sample holder (1) according to claim 8, further comprising - means for holding together the third frame member (41) and the first mask (10).
  10. A method of laser/light flash analysis of a plate-shaped sample, comprising - irradiating two first rectangular areas on a first side of the sample with an electromagnetic excitation pulse from a radiation source, - detecting thermal radiation emitted from a second rectangular area on a second side of the sample opposite to the first side as a result of the excitation pulse by means of a radiation detector, wherein a longitudinal axis of the second rectangular area is parallel to a longitudinal axis of the two first rectangular areas but offset orthogonally to the direction of the longitudinal axis of the two first rectangular areas, wherein the sample is held in a sample holder (1) according to any one of the preceding claims.

Description

The present invention relates to a sample holder for holding a plate-shaped sample in a laser/light flash analysis according to claim 1. A laser/light flash analysis of a sample, usually also referred to as "LFA", well known from the prior art comprises irradiating a first side of a sample with an electromagnetic excitation pulse from a radiation source (e.g. a laser or a flash light source), and detecting thermal radiation, which is emitted from a second side of the sample opposite to the first side as a result of the excitation pulse, by means of a radiation detector (e.g. an IR detector). In many application cases and in view of the invention described below, a more specific embodiment of such an LFA is of interest, which is often also referred to as an "in-plane LFA" and whose characteristic features are that: the irradiation with the electromagnetic excitation pulse is carried out only in one or more predetermined localised subareas on the first side of the sample, andonly thermal radiation emitted from one or more predetermined localized subareas on the second side of the sample as a result of the excitation pulse is detected, wherein said localized areas on the second side of the sample are offset orthogonally to the normal of the sample plane with respect to the localized areas on the first side of the sample. For the implementation of such an in-plane LFA, the applicant has in the past developed and tested, for example, sample holders according to claim 1, i.e. for holding a plate-shaped sample having a first side and a second side opposite to the first side, wherein the laser/light flash analysis comprises: irradiating two first strip-shaped areas on the first side of the sample with an electromagnetic excitation pulse from a radiation source, anddetecting thermal radiation emitted from a second strip-shaped area on the second side of the sample as a result of the excitation pulse by means of a radiation detector, wherein a longitudinal axis of the second strip-shaped area is parallel to the longitudinal axes of the two first strip-shaped areas but symetrically offset orthogonally to the direction of the longitudinal axes of the two first strip-shaped areas, and wherein the sample holder comprises: a first mask provided to face the radiation source during the laser/light flash analysis and defining two first slits corresponding to the two first strip-shaped areas on the first side of the sample, for providing a selective irradiation of the two first strip-shaped areas,a second mask provided to face the radiation detector during the laser/light flash analysis and defining a second slit corresponding to the second strip-shaped area on the second side of the sample, for providing a selective detection of radiation emitted from the second strip-shaped area, anda receiving space provided between the first mask and the second mask for receiving the sample with the first side facing the first mask and the second side facing the second mask. Such a "slit-in-plane sample holder" can advantageously be used for measurements of in-plane thermal diffusivities, i.e. orthogonal to the direction of passage of the heat transfer (heat conduction and/or radiation) through the sample. In the LFA and the in-plane LFA, a temporal progression of the detected intensity of the thermal radiation emitted from the second side of the sample is characterised primarily by a half-time, which can be defined, for example, as half of the time that is required to reach the maximum of the registered detector signal after the excitation pulse has hit the first side of the sample. If "d" denotes the lateral distance between the first slit (irradiation area) and the second slit (detection area) and "a" the thermal diffusivity of the sample measured in the plane of the sample in the direction orthogonal to the slits, the aforementioned half-time results as proportional to the expression d2 / a. Due to the given fixed arrangement of the slits in the known sample holder, the numerator (d2) in this expression is constant. Therefore, a decreasing thermal diffusivity (a) leads to longer measurement times. However, with longer measurement times, a heat exchange between the sample and an environment of the sample (in particular e.g. sample holder), which cannot be completely avoided in practice, can make a parasitic contribution to the measured signal (The contribution of the sample holder to heat exchange adds uncertainty to the thermal diffusivity measurement). This finally leads to a biased value of the thermal diffusivity determined by means of the LFA. On the other hand, if the measurement time is too short, additional uncertainty is associated with the finite pulse effects. Therefore, the distance "d" between the slits is ideally selected experimentally so that the measurement time in the LFA lies within a desired range (usually e.g. about 100 ms). Another result of the applicant's tests of the slit-in-plane sample holder is that the widt