Bird friendly electrochromic devices
Various embodiments herein relate to electrochromic windows that are bird friendly, as well as methods and apparatus for forming such windows. Bird friendly windows include one or more elements that make the window visible to birds so that the birds recognize that they cannot fly through the window. An electrochromic window includes one or more transparent substrates, wherein at least one of the substrates is an electrochromic (EC) lite including an electrochromic device and a pattern formed on at least one of the substrates by a laser, the pattern including a first feature configured to provide a set of optical properties different than optical properties of the transparent substrate. The set of optical properties includes one or more characteristics of refractivity, reflectivity and diffraction.
1. A method of fabricating an electrochromic (EC) window, the method comprising:
preparing an EC lite of the EC window by disposing an EC device on a first transparent substrate, and
forming, with a laser, a pattern on or in at least one of the EC lite and a second transparent substrate of the EC window, the pattern including a first feature configured to provide a set of optical properties different than optical properties of the transparent substrates; wherein
the set of optical properties includes one or more characteristics of refractivity, reflectivity and diffraction;
the laser operating regime includes a train of micro-pulses, each micro-pulse being less than 10 nanoseconds duration; and
the train of micro-pulses integrates into a laser exposure period of about 100-1000 microseconds.
2. The method of claim 1 , wherein forming the pattern on the EC lite includes operating the laser in a regime selected to form the pattern without damaging electrochromic device.
3. The method of claim 1 , wherein forming the pattern on the EC lite includes operating the laser in a regime selected to form the pattern elements by inducing local changes to a refraction index of the EC lite.
4. The method of claim 3 , wherein the laser-induced local change to the refraction index is configured to result in the pattern being visible to birds and invisible to humans.
5. The method of claim 3 , wherein the laser operating regime results in a pulse fluence that creates local densification of the EC lite that locally increases the refractive index of the EC lite and is below a microcracking threshold of the EC lite.
6. The method of claim 5 , the train of micro-pulses includes less than 100 micropulses.
7. The method of claim 5 , the train of micro-pulses includes less than 20 micropulses.
8. The method of claim 1 , wherein the pattern includes a diffraction grating on a surface of the EC lite opposite to the electrochromic device and forming the diffraction grating on the EC lite includes operating the laser in a regime selected to locally ablate micro-spots, each micro-spot having a dimension in the range of 1 to 50 μm.
9. The method of claim 8 , wherein the micro-spots have a diameter to depth ratio greater than 20.
10. The method of claim 1 , wherein the pattern comprises elements including one or more intersecting or non-intersecting stripes or bars and/or a plurality of dots.
11. The method of claim 1 , wherein the pattern is formed on the EC lite.
12. The method of claim 11 , wherein the pattern is formed on a surface of the EC lite opposite to the electrochromic device.
13. The method of claim 11 , wherein the pattern includes a sequence of microcracks formed on a surface or in an interior of the EC lite by operating the laser.
14. The method of claim 1 , wherein the electrochromic window is configured such that the pattern is positioned outboard of the electrochromic device.
15. The method of claim 1 , wherein the pattern is formed on the window after the EC lite and at least one additional transparent substrate are formed into an insulated glass unit (IGU).