Page 382 - Introduction to Information Optics

7.2. Recognition by Correlation Detections

CCDl

partially
coherent
light

SIM 2
Fig. 7.15. A high-light-efficient JTC.

we see that the JTPS as detected by the joint-transform operation can be
actually replicated into an N x N spectral array on SLM2. The corresponding
amplitude transmittance distribution of the replicated JTPSs can be written as

T(p t q) = 2 cos[2x 0(j> - ndj]}. (1.5)

We see that the overall correlation diffraction efficiency can be written as

2
ISU(x,y)®f(x,y)'] dxdy
2 (7.6)
l/R$$\u(x,y)\ dxdy
2
which increases about N times.
Let us provide a result, which was obtained by replicating the JTPS into
3x 3 arrays. The correlation spots under the coherent and partial coherent
readouts are shown in Fig. 7.16. We see that the correlation intensity under the
coherent readout is higher and sharper than the one obtained under the partial
coherent readout. However, the output signal-to-noise ratio seems to be lower
as compared with the partial coherent case. As discussed in Chapter 2, JTCs
can perform all the processing operations that an FDP can offer. The
high-efficiency JTC can also be used as a generalized image processor.