Optical measurement of thin films
Embodiments of measurement apparatus for measuring the optical properties of a sample film are described. The measurement apparatus includes a first stage, a second stage, and an arm structure coupled to the second stage. The first stage includes an optical source and a block of transparent material. The block of transparent material includes a surface that supports a sample film. The second stage includes a plurality of layers and an optical detector. The arm structure is designed to translate the second stage with respect to the first stage.
1. An apparatus configured to measure optical properties of a sample film, the apparatus comprising:
a first stage comprising:
an optical source, and
a block of transparent material, wherein a surface of the block of transparent material is configured to support the sample film;
a second stage comprising:
a plurality of layers comprising at least one diffuser film,
an optical detector, and
a metal sheet disposed between the optical detector and the plurality of layers; and
an arm structure coupled to the second stage, and configured to translate the second stage with respect to the first stage.
2. The apparatus of claim 1 , wherein the plurality of layers comprises at least one light-recycling film.
3. The apparatus of claim 1 , wherein the second stage further comprises a second block of transparent material such that the sample film is sandwiched directly between the block of transparent material and the second block of transparent material when the second stage is brought into contact with the first stage.
4. The apparatus of claim 3 , wherein the second stage further comprises a third block of transparent material such that the plurality of layers are sandwiched between the second block of transparent material and the third block of transparent material.
5. The apparatus of claim 1 , wherein the optical detector is a spectrometer.
6. The apparatus of claim 1 , wherein the arm structure comprises a plurality of beams coupled to the second stage.
7. The apparatus of claim 1 , wherein the arm structure is further coupled to one or more springs.
8. The apparatus of claim 1 , wherein the optical source comprises one or more blue light emitting diodes.
9. The apparatus of claim 1 , wherein the arm structure is configured to translate the second stage between a first position such that the first stage contacts the second stage and a second position such that the second stage is positioned apart from the first stage.
10. The apparatus of claim 1 , wherein the second stage comprises a light shield around a perimeter of the second stage.
11. A method of measuring optical properties of a sample film, the method comprising:
placing the sample film onto a first stage;
positioning a second stage onto the sample film using an arm structure coupled to the second stage, such that the sample film is sandwiched between the first stage and the second stage, the second stage having an optical detector, a given layer structure with at least one diffuser film, and a metal sheet disposed between the optical detector and the given layer structure;
generating light via an optical source in the first stage;
receiving light at the optical detector; and
determining one or more optical properties of the sample film based on the light received by the optical detector.
12. The method of claim 11 , wherein the determining comprises determining a peak wavelength of light emission from the sample film when the sample film includes a luminescent material.
13. The method of claim 11 , wherein the determining comprises determining a full-width half-max (FWHM) of a spectrum associated with the sample film when the sample film includes a luminescent material.
14. The method of claim 11 , wherein the determining comprises determining a brightness of the sample film when the sample film includes a luminescent material.
15. The method of claim 11 , wherein receiving light at the optical detector comprises receiving light generated by a luminescent material in the sample film.
16. The method of claim 15 , wherein the luminescent material comprises a plurality of quantum dots.
17. The method of claim 11 , wherein positioning the second stage comprises translating the second stage from a first position separated apart from the first stage to a second position where the second stage contacts the sample film.
18. The method of claim 17 , wherein the first position is at least 15 centimeters above the first stage.
19. The method of claim 11 , wherein the first stage includes a first block of transparent material, and the sample film is placed on the first block of transparent material.
20. The method of claim 19 , wherein the second stage includes a second block of transparent material, and positioning the second stage comprises lowering the second stage onto the sample film such that the sample film is sandwiched directly between the first block of transparent material and the second block of transparent material.