polarizing microscope
Date1850-1900
Inventory Number1205
ClassificationPolarimeter
Subject
Collector
Harold C. Ernst
?
1856 - 1922
User
Department of Geology and Geography, Harvard University
1890 - 1961
Cultural Region
Dimensions31.5 × 11 × 20 cm (12 3/8 × 4 5/16 × 7 7/8 in.)
Material
DescriptionThis instrument looks like a microscope. The base is V-shaped and supports a mirror and a stack of glass plates, acting as a polarizer. Both mirror and glass plates pivot. They are fixed in place by a screw found on each side of the pivot axes. In the middle is a circular stage with a condenser. The stage would also hold the transparent sample to be analyzed. The stage rotates and is used to measure the angle of rotation of the polarized light passing through the sample. There is a silvered scale for this purpose. Above the stage is an optical tube and eyepiece, in which is found a Nicol prism (the analyzer). The tube and condenser simply slide up and down for coarse adjustment.
Signedunsigned
Curatorial RemarksFrench physicist Etienne Louis Malus (1775-1812) discovered the polarization of light by reflection in 1808 and double refraction (bi-refringence) in crystals in 1810. The explanation of the first phenomena is a convincing demonstration of the transverse nature of light waves and leads to Malus' law, which describes the intensity of polarized light in terms of the square of the cosine of the angle of polarization. The polarizing microscope was devised by Giovan Battista Amici (1786-1863) around 1830. German chemist Johann Gottlieb Christian Nörrenberg (1787-1862) was the first to use a Nicol prism as an analyser with this form of apparatus (c. 1830-1840).
FunctionThis instrument would have been used to measure the optical rotation of light caused by a transparent substance. Particularly, in this case, for petrological studies.
Sunlight (most likely) would be reflected from the plain mirror onto the stack of glass plates (polarizer), which would polarize the light and refract it upwards. This polarized light would encounter a condenser (to focus the light), held in place by a stage, on which would be put the transparent sample to be analyzed. Light would go through the sample and up towards the tube and eyepiece, which has the analyzer (a Nicol prism). The angle of polarization is measured by rotating the stage, on which is a graduated scale.
For other types of polarimeters, see the following website.
Sunlight (most likely) would be reflected from the plain mirror onto the stack of glass plates (polarizer), which would polarize the light and refract it upwards. This polarized light would encounter a condenser (to focus the light), held in place by a stage, on which would be put the transparent sample to be analyzed. Light would go through the sample and up towards the tube and eyepiece, which has the analyzer (a Nicol prism). The angle of polarization is measured by rotating the stage, on which is a graduated scale.
For other types of polarimeters, see the following website.
ProvenanceFrom the Department of Geology and Geography, mineralogy section, Harvard University.
Jean Baptiste François Soleil
Date: 1840-1860
Accessories: carrying case; objective; double refraction ocular; substage polarizer; rotating stage plate; horizontal case; stage forceps; oculars (2)
Object number: 1215
Ernst Leitz (company)
Date: circa 1919
Accessories: oculars (2): 3, 8x; accessory box; Leitz objectives (5); wrenches (2); ground glass; N.A. 1.45 condensor cap; Abbe condensor; rotary stage; case
Object number: 1345
Ernst Leitz (company)
Date: 1950-1960
Accessories: carrying case
Object number: 2004-1-0375
Ernst Leitz (company)
Date: circa 1937
Accessories: standard eyepieces (3): 8X P, Periplan. OK 10X, and Periplan. Ok. 25X; wide eyepieces (3): 1, 1, 8X, 10X; objectives (4) in fitted case: 1b 4.3X, 3 10X, P7 62X, P 1/12 oel; waveplates (2); condenser with polarizer; mechanical stage; loupe 6x; box of cover glasses; standing case; key; objective adaptors (4); and watch keys (2)
Object number: 1999-1-0020a
R. & J. Beck
Date: 1876
Accessories: oculars (2) in microscope; Darker's selenite retarding filters (3); wheel diaphragm; mechanical rotary stage; stage slider. Other accessories are in the case (1122b), including monocular draw tube; oculars (3); objectives in cans (5); empty can; Lieberkühn; polarizing set; slides; camera lucidas (2); etc.; plus a Beck patent substage condenser (1122c); and apertometer (1122d).
Object number: 1122a
Spencer Lens Company
Date: circa 1937
Accessories: objectives in quick-release mounts (3): Spencer 6x and 20x, B&L 45x; full wave plate; quartz wedge; rotary vernier stage; Abbe condenser; Ahrens prism polarizer; case
Object number: 1320
Louis Jules Duboscq
Date: circa 1875
Object number: 1997-1-1477a
Spencer Lens Company
Date: circa 1940
Accessories: oculars (3): 6x, 10x, and pinhole; objectives (4): B&L 45x, AO 40x, Spencer 10x, B&L 16 mm; quick-change objective holders (2); quick-change centerable objective holders (3); petrographic substage condenser and polarizer; Amici-Bertrand lens; Polaroid analyzer; quartz wedge; full-wave plate; blue filters; case, key
Object number: 1378a
Ernst Leitz (company)
Date: circa 1948
Accessories: objectives (2): P3b A 0.40 16,5:1 C and P6L A 0.65 45:1; ocular "0"; polarizing condenser; analyzer; box with 14 older petrographic slides [1346b]; standing case
Object number: 1346a