Optics: measuring and testing – By particle light scattering – With photocell detection
Patent
1992-10-30
1995-08-29
Turner, Samuel A.
Optics: measuring and testing
By particle light scattering
With photocell detection
359370, G01B 902
Patent
active
054465400
ABSTRACT:
A phase-contrast microscope with a quarter-wave plate in a pupil plane with a thickness of .lambda..theta./2.pi. is provided for the inspection of a phase-shifting mask. The angle .theta. and the wavelength .lambda. are adjustable to optimize the phase detection sensitivity. A similar .theta. and .lambda. optimization scheme is applied to an interference microscope assembly wherein an inspection beam is split into two beams by a beam splitter to be reflected by mirrors and then recombined at a second beam splitter. A mirror in one of the beams can be moved to change .theta. to its optimum value at a given .lambda. which can be changed by light source selection or by filter change.
REFERENCES:
patent: 2685228 (1954-08-01), Kavanagh
patent: 4446548 (1984-05-01), Bouwhuis et al.
patent: 5124927 (1992-06-01), Hopewell et al.
patent: 5246801 (1993-09-01), Pierrat
Lin, Burn J., "Phase-Shifting and Other Challenges in Optical Mask Technology" 10th Annual Symposium on Microlithography, SPIE vol. 1496, pp. 54-78, Sep. 26-27, 1990.
M. Born & E. Wolf, Principles of Optics, Pergamon Press, 3rd Edition, pp. 300-302, 424-428. 1964.
Crockatt Dale M.
International Business Machines - Corporation
Jones II Graham S.
Kim Robert
Turner Samuel A.
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