The Evaluation of a LOMO Interference Rotary Monochromator and Its Adaptation to an Olympus Microscope and Performance Evaluations of Selected Interference Filters and Monochromators
THE MICROSCOPE
2026, Volume 73:2, pp. 64–74
DOI
https://doi.org/10.59082/PSCP9106
AUTHOR
Thomas A. Kubic, Antonio Del Valle, and Nicholas Petraco
ABSTRACT
For a number of years, Leningrad Optical Mechanical Association (LOMO), based in St. Petersburg, marketed microscopes to the West including the United States. Originally represented by LOMO America, Inc., of Prospect Heights, IL, and now discontinued by the Russian optical manufacturer, is the POLAM-L quantitative, transmitted polarized light microscope which includes many additional interesting options and accessories for the trained microscopist, such as phase contrast, dark-field, microscope objectives for higher than 10× focal plane [dispersion] staining, and an adjustable aperture contained within its viewing head to assist with conoscopic imaging of small particles.
Another accessory for the POLAM-L is the LOMO rotary interference monochromator that operates by utilizing a set of six different interference filters rotated into the light beam path. The transmitted wavelengths can be varied by tilting, i.e., manually changing the angle of the continuum of radiation incident to its surface. Forensic microscopists often use interference filters for the measurement of refractive indices and dispersion with high accuracy and precision. Some of the methodologies employ dispersive monochromators as sources, while others use high quality precision interference filters. Dispersive devices are expensive and the ability to employ a filter monochromator might be a valuable alternative. In this paper, the authors report the performance characteristics of a number of interference filters determined by employing a fiber optic spectrometer for which the calibration has been verified. The performance of a LOMO interference rotary monochromator (МИП-2) is also reported by evaluating the wavelength of maximum transmission determined by the spectrometer as a function of angle of incidence and compared to the wavelength calculated by the theoretical equation for the prediction of this wavelength. In addition, the author’s in-house constructed adapter for attaching and employing this accessory with an Olympus BHS polarized light microscope is described. The authors report on the performance of two dispersive monochromators (Bausch & Lomb) of the style often employed by forensic microscopists for high quality refractive index determinations on glass particles.
Another accessory for the POLAM-L is the LOMO rotary interference monochromator that operates by utilizing a set of six different interference filters rotated into the light beam path. The transmitted wavelengths can be varied by tilting, i.e., manually changing the angle of the continuum of radiation incident to its surface. Forensic microscopists often use interference filters for the measurement of refractive indices and dispersion with high accuracy and precision. Some of the methodologies employ dispersive monochromators as sources, while others use high quality precision interference filters. Dispersive devices are expensive and the ability to employ a filter monochromator might be a valuable alternative. In this paper, the authors report the performance characteristics of a number of interference filters determined by employing a fiber optic spectrometer for which the calibration has been verified. The performance of a LOMO interference rotary monochromator (МИП-2) is also reported by evaluating the wavelength of maximum transmission determined by the spectrometer as a function of angle of incidence and compared to the wavelength calculated by the theoretical equation for the prediction of this wavelength. In addition, the author’s in-house constructed adapter for attaching and employing this accessory with an Olympus BHS polarized light microscope is described. The authors report on the performance of two dispersive monochromators (Bausch & Lomb) of the style often employed by forensic microscopists for high quality refractive index determinations on glass particles.
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