Concave Rowland-type diffraction grating on speculum metal, grating area 139 x 57 mm, with scratched markings reading 'Ruled at J. H. U. 1934 / R. W. Wood & W. H. Perry / 30,000 lines per inch / 21' radius of curvature'. (J. H. U. = Johns Hopkins University.)
Details
- Category:
- Optics
- Object Number:
- 2000-1447
- Materials:
- speculum metal
- Measurements:
-
overall: 24 x 160 mm
- credit:
- Imperial College of Science,Technology & Medicine (Spectroscopy Group)
