Table I
The isolation of mercury arc radiations with color filters. The filters are characterized in the first column by their wave-length “centers of luminosity.” Their composition is shown in the second column; C.=Corning, J.=Jena (Schott und Gen.), W.=Wratten (Eastman). In the third column is shown the radiation of the high-pressure mercury arc transmitted by the filters, as viewed visually in a spectroscope, or—in the case of the 365 filter—a quartz spectrograph.
Filter (mμ) | Composition | Spectroscopic transmission of Hg radiation |
---|
365 | C. 5860, 738; J. BG12 | Lines at 365–366 mμ. |
405 | C. 3060, 4305, 5970 | Bright line at 405, dim line at 408 mμ |
436 | C. 3389, 5113 | Very bright line at 436, dim lines at 434, 435 mμ; dim continuum at 436–438 mμ. |
492 | W. 75, 48 | Brighter line at 492 mμ, dimmer at 496 mμ; dim continuum about 471–490 mμ. |
546 | W. 74, C. 5120 | Very intense line at 546 mμ, flanked by dim continuum to 549, very dim continuum to 536 mμ. |
578 | C. 4303, 3480 | Intense lines at 577, 579 mμ. |
621 | C. 2412, 9780 | Bright line at 623, dim line at 612 mμ. Continuum from about 609–635 mμ. |
691 | W. 91, C. 3962 | Bright line at 691 mμ, dim continuum from about 670–710 mμ. |
713 | W. 88, C. 3962 | Line at 707 mμ with dim continuum fading toward longer wave-lengths. |
750 | C. 5031, 2403; J. BG17 | Continuum from about 735–777 mμ. |
Table II
Stability of radiation of the high pressure mercury arc. Energies at various wave-lengths, measured at intervals over a period of 17 months, at the exit field of the adaptometer. Energies are in arbitrary units, relative to that at 578 mμ. Only data involving filter combinations used continuously for long periods are shown; omissions in the table mark points at which filter combinations were changed.
Radiation (mμ) | Relative energy |
---|
6–25–43 | 8–3–43 | 11–11–43 | 1–4–44 | 4–18–44 | 4–24–44 | 7–23–44 | 11–29–44 | Averages |
---|
365 | — | — | 10.12 | 10.13 | 9.70 | 9.60 | 10.21 | 9.61 | 9.90 |
405 | 1.21 | 1.24 | 1.18 | 1.20 | 1.21 | 1.21 | 1.23 | 1.17 | 1.21 |
436 | 6.02 | 5.96 | 5.66 | 5.96 | 6.31 | 6.27 | 6.25 | 6.66 | 6.14 |
546 | — | — | — | 1.10 | 1.08 | 1.08 | 1.10 | 1.16 | 1.10 |
578 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
621 | — | 0.060 | 0.062 | 0.063 | 0.067 | 0.067 | — | — | 0.064 |
750 | — | — | 1.95 | 2.03 | 1.95 | 1.90 | 1.83 | 2.18 | 1.97 |
Table III
Test of filters by reinforcement. In this test the absolute threshold of vision is measured through a filter supposed to isolate a restricted region of the spectrum, and again through this filter combined with another of similar properties. Red filters are thus tested by reinforcement with the red Corning 2412, and an ultraviolet filter is tested with the Jena UG-1. If the filter being tested transmits only the expected wave-lengths, the added filter has the effect calculated from its spectrophotometric transmission at these wave-lengths. If the test filter, however, has a radiation leak elsewhere in the spectrum, the added filter—with very low transmission at these supposedly excluded wave-lengths—has an exaggerated visual effect.
| | Change in log visual threshold due to added filter |
---|
Filter | Composition | Calculated | Observed |
---|
Red (691 mμ) | W. 91, C. 3962 | | |
This +C. 2412 | | 0.05 | 0.08 |
Red (750 mμ) | C. 2403, C. 5031 | | |
This +C. 2412 | | 0.06 | 0.03 |
Ultraviolet (365 mμ) | C. 5860, C. 738, J. BG-12 | | |
This +J. UG-1 | | 0.22 | 0.16 |
Red (690 mμ) | W. 89, C. 3962 | | |
This +C. 2412 | | 0.05 | 0.31 |
Red (680 mμ) | W. 70, J. BG-19 | | |
This +C. 2412 | | 0.05 | 1.44 |
Red (>640 mμ) | W. 70 | | |
This +C. 2412 | | 0.06 | 1.32 |
Note: C.=Corning, J.=Jena, and W.=Wratten.
Table IV
Test of filters by exclusion. If a filter which supposedly transmits radiation in a restricted region is combined with one which excludes this region though transmitting elsewhere, the combination should be opaque, or may transmit a small fraction of radiation in the region of overlapping transmissions. Here the Jena BG-18, which excludes visible radiation longer than about 650 mμ, is used to test red filters; the combinations should be opaque or may transmit some visible red from an intense source. The Corning 3060 is similarly used to test an ultraviolet filter; the combination should be opaque.
Filter | Combined with | Appearance of sun through combination |
---|
Wratten 70 | Jena BG-18 | Bright violet |
Wratten 87 | Jena BG-18 | Very deep red |
Wratten 88 | Jena BG-18 | Opaque |
Wratten 88A | Jena BG-18 | Opaque |
Wratten 89 | Jena BG-18 | Deep Orange |
Wratten 89A | Jena BG-18 | Bright blue-green |
Jena RG-5 | Jena BG-18 | Deep red |
Jena RG-8 | Jena BG-18 | Deep red |
Corning 5860 | Corning 3060 | Deep red |