The optical fibres terminate in the distal tip where they produce a circle of pulsed eximer laser light consisting of high-energy short-duration pulses (135 ns) at low temperature (∼50°C) and shallow tissue penetration (∼100 µm).
To explore this, Dutta et al. performed optical mapping of transmembrane potentials in isolated Langendorff-perfused rabbit hearts during global no-flow ischaemia, with alternating blue (shallow tissue penetration) and red (deep penetration) excitation of a ratiometric voltage-sensitive dye, using a novel single-sensor multi-parametric optical mapping approach.
As shown in Fig. 7(a) below, although the total intensity decreased, the ratio of photons collected from the vessel lumen (deeper than 0.5 mm which is the vessel upper limit) increased relatively to the photons probing the shallow tissue as we increased the source to detector separation.
While such approaches can successfully target localized shallow-tissue tumors (Celli et al., 2010; Wachowska et al., 2011), they are impractical for treating malaria due to the dispersed nature of blood-stage infection, the sequestration of mature P. falciparum parasites along the vascular endothelium, and the requirement to illuminate every infected erythrocyte.
In comparison to OCT, confocal imaging has shallower penetration in tissue; however, RCM with near infrared (NIR) illumination has sufficient penetration depth for epithelial imaging [ 2].
Due to interest in multilevel excitation, the transmission through the backplane was measured as it may deposit light in a shallow region of tissue near the surface.
Steady-state detection of diffuse reflectance can be achieved with UV-visible light which has shallower penetration depths in tissue of less than 1 mm [ 24].
All these fishes have long needlelike dorsal spines with glandular venom-producing tissue and shallow channels and are thus capable of inflicting very painful but rarely fatal punctures.
Similarly, LC visibility would be worse in humans than in animals with thinner prelaminar tissues or shallower LCs, such as monkeys or pigs.
More recently, experimental studies in bats using EBLV-1 and EBLV-2 have shown that bats are likely to transmit the virus following a shallow bite to peripheral tissue [ 15, 16].
