Lot of 10 New-Old-Stock (NOS) Vintage Microfiche Lens Containing Thoriated Glass
Barrel Size: 27mm in diameter and about 34mm tall.
These 23x Microfiche Lenses feature a thoriated glass front element.
Made in Japan
Th-232 is an optimal choice for calibrating the Radiacode devices as it offers the three calibration points required to calibrate at the energy levels of 65, 583, and 2614 keV. We provide a procedure on Radiacode calibration using thoriated glass on our Learn page: .https://geigercheck.com/learn/
Thoriated glass is a high-refractive-index glass used in optical systems such as photographic and microfiche lenses, valued for its ability to produce sharp images with good color correction in compact designs. It contains thorium dioxide, making it radioactive—sometimes up to 30% by weight. Over time, the glass develops a brown tint due to radiation damage, which reduces light transmission and affects neutral color reproduction. While this tint can interfere with image quality, it can often be reversed with exposure to UV light. Thoriated glass has largely been replaced by lanthanum-based glass due to health and safety concerns.
Geiger counters and coin not included
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