Irina Harder, Gerd Leuchs, Klaus Mantel, and Johannes Schwider, "Adaptive frequency comb illumination for interferometry in the case of nested two-beam cavities," Appl. Opt. 50, 4942-4956 (2011)
The homogeneity test of glass plates in a Fizeau interferometer is hampered by the superposition of multiple interference signals coming from the surfaces of the glass plate as well as the empty Fizeau cavity. To evaluate interferograms resulting from such nested cavities, various approaches such as the use of broadband light sources have been applied. In this paper, we propose an adaptive frequency comb interferometer to accomplish the cavity selection. An adjustable Fabry–Perot resonator is used to generate a variable frequency comb that can be matched to the length of the desired cavity. Owing to its flexibility, the number of measurements needed for the homogeneity test can be reduced to four. Furthermore, compared to approaches using a two-beam interferometer as a filter for the broadband light source, the visibility of the fringe system is considerably higher if a Fabry–Perot filter is applied.
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
You do not have subscription access to this journal. Figure files are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
You do not have subscription access to this journal. Article tables are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
You do not have subscription access to this journal. Equations are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
Measured Optical Cavity Length for the Cavities of the Nested Configuration via the Resonant Cavity Lengths of the FP Filtera
Optical cavity length
FP filter cavity/mm
Refractive index N is the group index for the BK7 plate. Thickness of the glass plate in the center can be derived from the above values to .
Table 2
Visibility Figures for Single Cavities in Presence of Incoherent Intensity Contributions from Competing Cavitiesa
Combination
Combination
Combination
Combination
Combination
Spatially coherent light has been assumed for the calculation of the visibility figures of the resonant cavities. The above visibility values have to be multiplied with the reflectivity of the FP filter, which in our actual experiment is .
Table 3
Visibility Figures for the Case of Spatially Blocked Intensity Contributions from Parasitic Cavities, Assuming Spatially Coherent Lighta
Surfaces
Surfaces
The visibility value for the empty cavity with the surfaces has been omitted because it is even closer to 1. The latter measurement would be necessary to remove the surface contributions of the Fizeau cavity from the homogeneity data.
Tables (3)
Table 1
Measured Optical Cavity Length for the Cavities of the Nested Configuration via the Resonant Cavity Lengths of the FP Filtera
Optical cavity length
FP filter cavity/mm
Refractive index N is the group index for the BK7 plate. Thickness of the glass plate in the center can be derived from the above values to .
Table 2
Visibility Figures for Single Cavities in Presence of Incoherent Intensity Contributions from Competing Cavitiesa
Combination
Combination
Combination
Combination
Combination
Spatially coherent light has been assumed for the calculation of the visibility figures of the resonant cavities. The above visibility values have to be multiplied with the reflectivity of the FP filter, which in our actual experiment is .
Table 3
Visibility Figures for the Case of Spatially Blocked Intensity Contributions from Parasitic Cavities, Assuming Spatially Coherent Lighta
Surfaces
Surfaces
The visibility value for the empty cavity with the surfaces has been omitted because it is even closer to 1. The latter measurement would be necessary to remove the surface contributions of the Fizeau cavity from the homogeneity data.