US 12,241,781 B2
Device and method for measuring optical constant
Daisuke Hirano, Tokyo (JP); Makoto Gonokami, Tokyo (JP); and Kosuke Yoshioka, Tokyo (JP)
Assigned to THE UNIVERSITY OF TOKYO, Tokyo (JP)
Filed by THE UNIVERSITY OF TOKYO, Tokyo (JP)
Filed on Feb. 15, 2022, as Appl. No. 17/672,114.
Application 17/672,114 is a continuation of application No. PCT/JP2020/030878, filed on Aug. 14, 2020.
Claims priority of provisional application 62/887,077, filed on Aug. 15, 2019.
Prior Publication US 2022/0252453 A1, Aug. 11, 2022
Int. Cl. G01J 3/18 (2006.01); G01J 3/02 (2006.01); G01J 3/10 (2006.01); G01J 3/28 (2006.01); G01J 3/45 (2006.01)
CPC G01J 3/18 (2013.01) [G01J 3/0229 (2013.01); G01J 3/10 (2013.01); G01J 3/2823 (2013.01); G01J 3/45 (2013.01)] 11 Claims
OG exemplary drawing
 
1. An optical constant measurement apparatus comprising:
a coherent light source structured to output coherent light including high-order harmonics obtained by irradiating short-pulse laser light to a nonlinear medium;
a spectrometer comprising a grating structured to diffract the coherent light and an image sensor structured to measure an image of light diffracted by the grating;
a first double slit having a pair of apertures arranged with an interval in a first direction, which are arranged at a predetermined position between the coherent light source and an incident slit of the spectrometer in a first state;
a second double slit having a pair of apertures that are a replica of the first double slit, which are arranged at the predetermined position as a replacement of the first double slit in a state in which one from among the pair of apertures holds a sample in a second state; and
a calculation processing device structured to calculate optical constants of the sample based on a first interference image formed on the image sensor due to the harmonics of the coherent light in the first state and a second interference image formed on the image sensor due to the harmonics in the second state, wherein the optical constant measurement apparatus in the first state and the optical constant measurement apparatus in the second state are respectively modeled using parameters,
wherein the calculation processing device calculates a first intensity distribution formed on the image sensor in the first state based on a first model representing the optical constant measurement apparatus in the first state using a one-dimensional Fresnel diffraction expression,
the calculation processing device calculates a second intensity distribution formed on the image sensor in the second state based on a second model representing the optical constant measurement apparatus in the second state using the one-dimensional Fresnel diffraction expression,
and wherein the calculation processing device calculates the parameters of the first model and the second model and the optical constants of the sample such that the first intensity distribution matches the first interference image and the second intensity distribution matches the second interference image.