This kind of glass only transmits the light within a narrow wavelength range as shown in figure. Its spectral characteristic is composed of maximum transmissivity (TM) wavelength of the peak (lM), front-cut-off wavelength, behind-cut-off wavelength, and half-peak width.
The wavelength corresponding to the half of the maximum transmissivity are l2 and l1. And the half-peak width is determined by l2 – l1. Front (behind)-cut-off wavelength is corresponding to the wavelength of “zero” transmissivity. But there are a few types which transmissivities of the behind-cut-off wavelengths can’t approach to zero, then they are determined by the transmissivity of the certain wavelength.
Band-Pass Filter Glass is named DTB, and wavelength of the peak is used as its serial number.
Spectrum Characteristic Curve of Band-Pass Filter Glass
Technical Indexes
| No. | Type | Maximum Transmissivity (TM/lM nm) | Front Cut-off (T/l nm) | Behind Cut-off (T/l nm) | Half-peak Width l2 – l1 (nm) | Thickness (nm) |
| 1 | DTB400 | >45/400+/-2 | 0/320+/-5 | 0/525+/-5 | <90 | 2 |
| 2 | DTB435 | >48/435+/-2 | 0/340+/-5 | <2.0/540+/-5 | <100 | 4 |
| 3 | DTB470 | >40/470+/-2 | 0/340+/-5 | 0/600+/-5 | <115 | 4 |
| 4 | DTB500 | >48/500+/-2 | 0/380+/-5 | 0/630+/-5 | <100 | 4 |
| 5 | DTB530 | >48/530+/-2 | 0/420+/-5 | 0/670+/-5 | <95 | 2 |
| 6 | DTB545 | >48/545+/-2 | 0/400+/-5 | 0/720+/-5 | <100 | 4 |
| 7 | DTB560 | >40/560+/-2 | 0/435+/-5 | 0/725+/-5 | <104 | 4 |
| 8 | DTB600 | >36/600+/-2 | 0/470+/-5 | <1.0/800+/-5 | <95 | 4 |
| 9 | DTB660 | >44/660+/-2 | 0/500+/-5 | <2.0/800+/-5 | <115 | 4 |
| 10 | DTB700 | >28/700+/-2 | <0.5/570+/-5 | <2.0/820+/-5 | <95 | 4 |
| 11 | DTB720 | >50/720+/-2 | 0/500+/-5 | <9.0/900+/-5 | <140 | 4 |
| 12 | DTB740 | >25/740+/-2 | 0/650+/-5 | <4.0/900+/-5 | <85 | 4 |
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