Olympus UApo N 340 40x Oil Immersion Apochromat Objective (NA 1.35, UV, Infinity)

The Olympus UApo N 340 40× is a purpose-built UV apochromat objective designed around the specific requirements of fura-2 ratiometric calcium imaging — one of the most demanding UV fluorescence applications in cell biology. Fura-2 requires excitation at two UV wavelengths (340nm and 380nm) with the ratio of emission intensities used to calculate intracellular calcium concentration. This ratiometric approach demands an objective with high, consistent UV transmission at both excitation wavelengths, and the UApo N 340 is specifically optimized to deliver this performance. Standard fluorite and apochromat objectives designed for visible light imaging have significantly reduced transmission below 380nm, making them unsuitable for fura-2 ratiometric imaging where accurate 340nm excitation is essential. The UApo N 340 series addresses this by using optical glass with high UV transmission, ensuring that the 340nm excitation beam reaches the specimen with sufficient intensity for accurate ratiometric calcium measurements. At NA 1.35 with oil immersion, this objective also provides excellent fluorescence light collection efficiency — critical for UV fluorescence applications where the photon budget is inherently limited by UV excitation intensity and fluorophore brightness. Compatible with Olympus BX, CX, and IX series microscopes. Supplied new from stock, part number N4274000.