Petrological or polarization microscopes
Petrological or polarization microscopes are essentially optical microscopes with all their components that also polarize monochromatic light. After passing through the object of study, it is analyzed and its characteristics can be identified. These are complex devices that are also called mineralogical microscopes.
Fig 1. Ancient petrological microscope
Fig 2. Modern petrological microscopeo
The first devices with polarization accessories, already in the middle of the XIX century, facilitated the knowledge of minerals. Essential to the development of mineralogy as a science, the polarization microscope has evolved over the years with different models to observe and measure the optical properties of minerals. This technique is based on the changes that light undergoes as it passes through it to determine its structure and composition.
Essentially, petrology or polarization microscopes have two prisms. A double Nicol prism, under the condenser, which polarizes the monochromatic light that comes from the base and passes through it. The already polarized light passes through the condenser and reaches the stage, which is circular divided into 360º and has a rotary movement, where the sample to be observed is located.
After passing through the object, the rays reach the target and pass through the analytical polarizer, which is located in the optical tube. This is also called a sheet polarizer and it is easily removed (fig. 1 and 2). Finally, the image reaches the eyepiece. Although this device has maintained its essential structure over the years, it has continued to evolve until 1950. The initial models are characterized by their functional elegance, beauty being part of their design. Consequently, these models and their accessories have become collector’s items due to their aesthetics and qualities (fig. 3 and 4).
44c. Microscopio mineralógico portátil. Alemania. 1910.
44d. Microscopio mineralógico portátil. Swift&son. London. 1.900.
77. Microscopio de luz polarizada. Swift & son. Londres. c.1890
77a. Microscopio mineralógico Nachet. c1890
77b. Pequeño microscopio mineralógico. Nachet. c1895
78. Microscopio de luz polarizada. Swift & son. Londres. 1907
79. Gran microscopio monocular mineralógico. W. Watson & son. Londres
