. The microscope; an introduction to microscopic methods and to histology. Microscopes. 286 TUBE-LENGTH AND COVER-GLASS THICKNESS [Ch IX. glass. If the lenses are fixed in position in the objective it wiU be evident that one must select a cover-glass which is of the exact thickness to satisfy the correction of the objective. The makers of objectives are now very precise in stating exactly how thick the covers should be for their objectives, and it is the part of wisdom to pay heed to their statements if one hopes to get the best re- sults. If one's objectives are adjustable (§ 134-135), it is
. The microscope; an introduction to microscopic methods and to histology. Microscopes. 286 TUBE-LENGTH AND COVER-GLASS THICKNESS [Ch IX. glass. If the lenses are fixed in position in the objective it wiU be evident that one must select a cover-glass which is of the exact thickness to satisfy the correction of the objective. The makers of objectives are now very precise in stating exactly how thick the covers should be for their objectives, and it is the part of wisdom to pay heed to their statements if one hopes to get the best re- sults. If one's objectives are adjustable (§ 134-135), it is possible to so arrange the combinations that quite a range of cover-glass thickness. Fig. 169. Spherical Aberration Introduced by the Cover-glass. Axis The principal optic axis extending through the condenser and up through the object and microscope. Slide The glass slide on which the object is mounted. Object The object to be studied; it is mounted on the slide. Balsam The medium in which the object is mounted. It has practically the same refractive index as the cover. Cover-glass The thin glass plate over the object. 123 The light rays extending obliquely upward from the object. 321 Light rays traced backward to their apparent origin, the most oblique ray (j) being most bent, thus rendering its origin apparently highest. r r r Points of refraction of the three oblique rays. or mounting medium thickness can be used and still get the best optical effect by balancing the aberrations (§462). § 461. Tube-length. — The length of the tube on the microscope must be made of the standard for which the objective used was cor- rected or aberrations will appear. If the tube is shorter than the objective was corrected for, the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Gage, Simon Henry, 1851-1944. [Ithaca, N
Size: 2121px × 1178px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectmicroscopes, bookyear
