Laser diode sources operating at 638 nm have been used in pico projectors and other display applications due to their high brightness and low power consumption. Recently, these sources have become more stable, making them a viable option for Raman handheld or portable instruments. Many Raman instrument manufacturers have already started incorporating the 638 nm wavelength as an excitation option.<\/p>\n
Raman scattered light is extremely weak in comparison to the intense excitation light, so high performance optical filters are essential to observe the Raman signal while suppressing the excitation and background sources.<\/p>\n
Iridian\u2019s 638 nm Raman edge pass filters provide high transmittance (>90% absolute) and low ripple (<\u00b12%) for the Raman light in addition to an ultra-steep edge (cut-off < 50 cm-1<\/sup>) and better than OD 6 blocking at 638 nm.\u00a0 As a result, Iridian\u2019s edge pass filters are able to provide more signal with less background.<\/p>\n Iridian\u2019s new 638 nm laser line filter offers a narrow bandwidth (~2 nm FWHM), high transmittance, steep roll-off and wide blocking (300-1200nm). This reduces spectral noise without compromising transmittance at 638 nm.<\/p>\n