The intensity of the reflected light (λ = 546nm) perpendicular to the incident light on the polished surface of the vitrinite is measured by the photoelectric converter under the oil immersion objective of the microscope. The intensity of the reflected light is compared with that of the reference material with known reflectivity under the same conditions.
Due to the slight difference of optical properties among vitrinite particles in single coal seam, the difference is greater in mixed coal, so it is necessary to obtain enough measurement values from different particles to ensure the representativeness of the results.
The light source with enough brightness and stable output should be used, and the halogen quartz lamp with power of 50W or 100W should be used.
The polarizer can be sheet polarizer or prism polarizer.
Objective lens: it is suitable for polarizing and oil immersion lens with refractive index of 1.518. It has low diffuse reflectance and magnification of 20 ~ 60.
The eyepiece consists of two observation eyepieces, one of which shall be equipped with a cross wire. The magnification of observation eyepiece and test eyepiece should be consistent. The total magnification of eyepiece, objective and adapter should be between 250 and 750.
Resolution: the reading of instrument display should be able to distinguish 0.01% reflectivity.
During the detection process, the variation range of the measured value of any reference material within 30 minutes should not be greater than 2% of the standard value of the reference material.
The reflectivity should be linear between 0.59% and 7.45%. The difference between the measured value of any reference material and the standard value should not exceed ± 0.02%.
Method of detrmining microscoplly the reflectance of vitrinite in coal
MT/T1053-2008 Technical conditio of microscope photometer for vitrinite reflectance determination
a. Vitrosomes, transverse section, large tracheids of subsquare or subequidiameter polygons. b. Vitrinite of koda wood structure, diameter section. Shows cross fields and tight squeeze holes. c. Homogeneous vitrinite; d. vitrinite, secondary xylem, striatum.