Fig. 5.

Experimentally characterized resolution limits for two optical configurations of the light field microscope. (a) In a widefield microscope with no lenslet array, the target quickly goes out of focus when it is translated in z. (b) In a 3-D deconvolution from a light field, we lose resolution if the test target is placed at the native object plane (z = 0 μm), but we can reconstruct the target at much higher resolution than the spacing between lenslets when it is moved z = −15 μm (see also Fig. 1). Resolution falls off gradually beyond this depth (z = ±50 μm and ±100 μm). (c) Experimental MTF measured by analyzing the contrast of different line pair groupings in the USAF reconstruction. The colormap shows normalized contrast as measured using Eq. (10). The region of fluctuating resolution from z = −30 μm to 30 μm show that not all spatial frequencies are equally well reconstructed at all depths. (d) A slightly higher peak resolution (z = ±10 μm) can be achieved in the light field recorded with a 40× 0.8NA objective. However, the z = ±25 μm and ±50 μm planes in (d) have the same apparent resolution as the z = ±50 μm and ±100 μm planes in (b). (e) The experimental MTF for the 40× configuration shows that the region of fluctuating resolution (from −7.5 μm to 7.5 μm) is one quarter the size compared to (c). The solid green line in (c) and orange line in (e) are a 10% contrast cut-off representing the band limit of the reconstruction as a function of depth. Note that these plots are clipped to 645 cycles/mm, which is the highest resolution group on the USAF target.