Characterization of liquid crystal tunable filter spectral response with diverging incident light
The normalized spectral transmission of a liquid crystal tunable filter was characterized. Light was focused using a lens, and the diverging light from the focus is made incident to the LCTF. The output spectrum is measured by a spectrometer when the LCTF is set to allow a certain wavelength (λLCTF). We found that spurious transmissions are observed in wavelengths away from λLCTF, especially at higher effective NA.