| 摘要 |
PROBLEM TO BE SOLVED: To set a band from a visible range to a near-infrared range (particularly, a band from 400 nm to more than 1000 nm) to be a transmission band.SOLUTION: An optical filter 4 includes a crystal plate 6, and a filter group 8 formed on the crystal plate 6 and having transmission properties in two wavelength bands of a visible range and a near-infrared range. The filter group 8 includes a wide band transmission filter group 87 having transmission properties for continuous transmission of preset wavelengths from a visible range to a near-infrared range, and a preset wavelength of a near-infrared range is more than 1000 nm. |
