Fiber-optic plate (FOP) is an optical glass component comprised of a bundle of regularly arranged optical fibers with diameters of a few microns, fused and pressed together to transmit an image from one end-face to the other.
Design and principle of operation
The FOP has a multi-channel honeycomb structure. This component includes three principal glasses: conducting core, reflective cladding, and absorbing cladding. The principle of operation of the FOP is based on total internal light reflection.
Application
Fiber-optic plates are used as input and output windows of image intensifier tubes (IIT), and as screens of vacuum tubes and MCP detectors. As part of the application device, FOPs perform functions of transmission and switching of light signals, transmission of optical or electro-optical images, transformation of the cross sectional shape of the light signal, correction of the field curvature of the optical system.
A straight plane-parallel FOP is used at the IIT input. Various designs of FOPs are used at the output of the IIT:
- with 180° image inversion;
- straight, without image inversion.
FOP basic parameters
| Parameter, unit | Normal value |
|---|---|
| 1. Single fiber size, µm | 4.5 max |
| 2. Limiting resolution in the center, lp/mm | 110 |
| 3. Limiting resolution within the active area diameter without image inversion, lp/mm | 110 |
| 4. Limiting resolution within the active area diameter with 180° image inversion, lp/mm | 90 |
| 5. Transmittance at 550 nm: | |
| – for FOP without image inversion; | 0.55 (Ø 3 mm), 0.45 (Ø 17 mm) |
| – for FOP with image inversion | 0.55 (Ø 3 mm), 0.45 (Ø 17 mm) |
| 6. Structural non-uniformity of transmittance when scanning with a 20×20 μm light spot , % | 5 |
| 7. Image inversion angle (for a twister), degree | 180 (±1⁰) |
| 8. Numerical aperture | 1 |
| 9. Image shear distortion, μm | In the central area (Ø2 mm): 15 max, In the remaining area (Ø2 – 18.6 mm): 25 max. |
| 10. Image gross distortion within the entire active area diameter: | 60 |
| 11. Vacuum density, m3×Pa/с | 1×10-12 |
| 12. Output surface radii (for a spherical FOP), mm: | 40, 18 |