Efficiency at blaze is lower but the efficiency curve is flatter
17", but can be larger
Scattered light increases drastically with density
No increases of scatter with groove density
Volume HOEs can diffract 99% @ Bragg angle and center
.
| Property | Classical Gratings | HOEDGs |
|---|---|---|
| Efficiencies | 60 to 99% | 50 to 90% (surface relief only)
Efficiency at blaze is lower but the efficiency curve is flatter |
| Ghosts | At best 10-5 (usually 10-2) of parent line | No ghosts at all |
| Scattered light | At best 10-5 to 10-6 at 5Å of laser line in visible | At best 10-6 to 10-8 at 5Å of laser line in visible |
| Size | In general standard sizes are limited to 8x8" | Up to 17", but can be larger
|
| Number of grooves | Maximum 3600 lines/mm (There are rare exceptions.) Scattered light increases drastically with density | Up to 6000 lines/mm No increases of scatter with groove density |
| Optical power | No | Yes Volume HOEs can diffract 99% @ Bragg angle and center .
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