Humboldt State University
Robert A. Paselk Scientific Instrument Museum
Wide Field Binocular Microscope
Bausch & Lomb
Humboldt State College, 1946
This is a general purpose, low magnification (3 150 x) microscope used for three-dimensional viewing in biology (sometimes referred to as a dissecting scope), assembly and inspection in industry, etc. This type of low power, binocular microscope was first designed by Greenough in 1897, and was first manufactured by Zeiss.1 It consists of two independent microscopes with erecting prism systems focused on the same object from slightly different angles to give an exaggerated stereoscopic view. Because of the inclinations of the optical axis of the two microscopes from the vertical, only the center of the field is in focus for both, however, the composite image appears sharp over the entire field due to the opposite nature of the focusing errors, the accommodation of the eye, and the great depth of view of the low power objectives.
The microscope stands 9" high when closed, the base is 5 1/4" wide by 7 1/8" deep. It is scribed HSC 43765 on the right-hand stage-bracket and the right-hand prism cell next to the B&L logo and serial number (TP 484). The stand is finished in black crinkle-paint, while the base and optical head is black japanned. The 0.7x objectives are built in to the drum nose-piece. Two additional sets of objectives, 1.5x and 2.0x, are on dove-tail sliders. Both eyepieces are replacements as is the glass stage.
The identical instrument is described and illustrated as item 37271, Bausch and Lomb Wide Field Binocular Microscope Model AKW-5-With Stand A in the 1940 Braun-Knecht-Heiman-Co. catalog, pg. 697. According to a table in Bracegirdle2 this microscope was manufactured in 1946.
Three missing screws on the left prism housing were replaced with black steel flathead screws of the same thread size. The dust from the optics was removed by gentle swabbing with dampened lens tissue. Screws inside the prism boxes were tightened, but not adjusted (note: the alignment was out of adjustment as seen when eyepieces were placed into the instrument). All outer surfaces of the instrument were cleaned with a cotton cloth dampened with "Pledge" spray wax and polished. A new stage was made from old 3/16" plate glass, and sanded on all edges. The four screws holding the stage brackets were wire-brushed to remove surface rust, and reinstalled.
1Needham, George Herbert. The Practical Use of the Microscope. Charles C. Thomas Publisher. Springfield. (1958) p. 64.
2Bracegirdle, Brian. Notes on Modern Microscope Manufacturers. Quekett Microscopical Club, Oxford (1996) p 11.