Hologram 2
The hologram 2 surface is very similar to the hologram 1 surface. The key difference is that the hologram 1 surface assumes both construction beams either diverge from or converge to the construction points, whereas the hologram 2 surface assumes one construction beam converges to one construction point, and the other construction beam diverges from the other construction point. Which beam is first or second does not matter due to reciprocity. The parameter data is the same for both hologram 1 and hologram 2 surfaces.
Shown below are plots explaining how the beam's convergence and divergence are taken by Hologram 1 and 2. Note that the rays in orange represent diverging beams and the rays in green represent converging beams. We can see Hologram 1 takes the point sources as both being divergent, which is identical to the case where both construction beams converge toward the construction points due to reciprocity. On the other hand, Hologram 2 takes the two point sources as one divergent and one convergent. Which point source is divergent or convergent does not matter due to reciprocity.
PARAMETER DEFINITIONS FOR HOLOGRAM 2 SURFACES (Par 14-21 only used available Par 13 ≠ 0)
| Parameter # | Definition |
| 1 | X coordinate for first construction beam, Construct X1 |
| 2 | Y coordinate for first construction beam, Construct Y1 |
| 3 | Z coordinate for first construction beam, Construct Z1 |
| 4 | X coordinate for second construction beam, Construct X2 |
| 5 | Y coordinate for second construction beam, Construct Y2 |
| 6 | Z coordinate for second construction beam, Construct Z2 |
| 7 | Construction Wavelength, λc |
| 8 | Diffract Order, m |
| 13 | Volume Hologram? (0 for false, 1 for true) |
| 14 | Hologram Thickness (only used for efficiency calculations not ray-tracing) |
| 15 | Refractive index seen by construction beam 1 outside hologram, n1 |
| 16 | Refractive index seen by construction beam 2 outside hologram, n2 |
| 17 | Average refractive index of the hologram emulsion, n |
| 18 | Modulation of the refractive index, dn |
| 19 | Shrinkage (0 for no shrinkage, else scale of thickness e.g. 0.98 is 2% shrinkage) |
| 20 | Index Shift (change of average refractive index after developing) |
| 21 | Consider Fresnel? (0 for false, 1 for true) |
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