One of the least known regions of the cosmic electromagnetic background is in the infrared (IR). This infrared background (IRB) is of considerable astrophysical interest. Early stellar activity, either pregalactic (Bond, Carr and Hogan, 1986), or galactic (Partridge and Peebles, 1967), may have contributed significantly to the IRB. More significant, perhaps, are the superimposed IR emissions from normal galaxies, Seyferts, quasars, and rich clusters of galaxies (e.g., Stecker, Puget and Fazio, 1977). There are only few reported measurements of the IRB, which in general yield energy densities comparable to that of the Cosmic Microwave Background (CMB), ρ
≈4 10−13 erg cm−3. An upper limit on the energy density at 2 μm is δ ≡ ρ/ρ
≤1.2 (Hoffman and Lemke, 1978). Matsumoto, Akiba and Murakami (1984) have detected diffuse emission in the 2–5 μm band, with an estimated energy density δ = 1.2.