Broadband (achromatic) antireflection coatings
There are several ways to solve achromatization problems in our laboratory:
1) Obtaining of standard broadband antireflection coatings with decreased value of reflectance, for example for 400 - 700 nm (three-layered antireflection coating) due to usage of controllable refraction index inhomogeneity of layers.
2) Obtaining of extended achromatization bands (for example, 400 - 750 nanometers, 400 - 800 nanometers) with low value of reflectance, these are 4 - 7- layer coatings for various substrates materials (oxides and fluorides).
3) Obtaining of achromatic coatings for 350 - 950 or 350 - 1100 nanometers with increased reflectance (R <1-1.5 %). We have achieved very good results for BK-7 glass, including details which work with 45 degrees angle of incidence.
4) Nowadays we are developing a super achromatic coating for 250 - 900 nm wavelength range. There are difficulties, due to a limited choice of the materials working in UV range and with a high dispersion at the same range.
The examples of broadband antireflection coatings are shown on the curves below.