Nanometer grating window structure for improving light absorption rate of image intensifier
By introducing a nanograting window structure into the image intensifier, combined with a refractive index transition and an alumina passivation film, the problem of insufficient light absorption in the long wavelength band of multi-alkali photocathode materials was solved, achieving higher light absorption and better imaging effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHENGZHOU UNIV
- Filing Date
- 2025-06-27
- Publication Date
- 2026-07-17
AI Technical Summary
The existing multi-alkali photocathode material Na2KSb[Cs] has insufficient light absorption capacity in the long wavelength band, resulting in poor imaging performance of the image intensifier in low-light environments. Traditional structural design and fabrication processes have performance bottlenecks.
A nanograting window structure with a refractive index transition is introduced between the substrate and the multi-alkali photocathode layer. The interface reflection loss is reduced by the combination of the arrayed etching grooves and refractive pillars, and the optical performance is protected by an aluminum oxide passivation film to improve the light absorption rate.
It significantly improves light absorption in the 400-900nm wavelength range, enhances the low-light performance of the image intensifier, reduces interface reflection loss, and protects the optical performance from damage.
Smart Images
Figure CN224518989U_ABST
Abstract
Claims
1. A nano-grating window structure for increasing the light absorption of an image intensifier, characterized in that: It includes a substrate, a refractive thin film, an alumina passivation film layer, and a multi-alkali photocathode layer arranged sequentially from bottom to top. The upper surface of the substrate is a hybrid layer, and an array of etching grooves are provided on the hybrid layer. The etching grooves are filled with refractive pillars, and the upper ends of the refractive pillars extend to the lower surface of the refractive thin film.
2. The nano-grating window structure for improving the light absorption of image intensifier according to claim 1, characterized in that: The refractive index of the hybrid layer is between that of the substrate and the refractive film. The refractive index of the substrate is 1.4-1.6, the refractive index of the refractive film is 2.3-2.7, and the refractive index of the multi-alkali photocathode layer is 2.8-3.
7.
3. The nano-grating window structure for improving the light absorption rate of an image intensifier according to claim 1 or 2, characterized in that: The thickness of the refractive film is 150±5nm.
4. The nano-grating window structure for increasing the light absorption rate of an image intensifier according to claim 1 or 2, characterized in that: The thickness of the alumina passivation film is 2-4 nm.
5. The nano-grating window structure for increasing the light absorption of an image intensifier according to claim 1, wherein: The etching trenches are cylindrical, with a depth of 250-500nm and a duty cycle of 0.3-0.
7. The etching trenches are arranged in a regular hexagonal pattern.
6. The nano-grating window structure for increasing the light absorption rate of an image intensifier according to claim 1 or 2, wherein: The thickness of the multi-alkali photocathode layer is 220±10nm, and the multi-alkali photocathode layer is a Na2KSb[Cs] layer.
7. A nanograting window structure for improving the light absorption rate of an image intensifier according to claim 1 or 2, characterized in that: The refractive pillars and the refractive films are made of the same material; the refractive pillars are titanium dioxide pillars, titanium pentoxide pillars, or hafnium dioxide pillars.
8. The nano-grating window structure for increasing the light absorption rate of an image intensifier according to claim 1 or 2, wherein: The substrate is a borosilicate glass substrate, a borosilicate glass substrate, an alkali metal borosilicate glass substrate, or a SiO2 substrate.
9. The nano-grating window structure for increasing the light absorption of an image intensifier according to claim 1, wherein: The light transmittance of the alumina passivation film exceeds 90%.