Along with these advances, new improvements will continue to be made in the various characteristics of the established types of atomic frequency standards. New developments which are in progress include the thallium atomic beam controlled frequency standard and the active rubidium maser. It is also the largest and the cost is influenced by the more advanced performance characteristics. The atomic hydrogen maser, at present, has the highest degree of short-term stability, long-term stability, and intrinsic reproducibility when compared with the other commercially produced atomic frequency standards. The cesium standard also has a high degree of intrinsic reproducibility which qualifies it for service as a primary standard without the need for calibration. However, the long term stability is very high, and the limits have not yet been measured for very long averaging periods. Cesium atomic beam frequency standards are somewhat larger and heavier than rubidium standards, and the short-term stability is limited by shot noise in the cesium tube resonance signal. The cost of rubidium frequency standards is less than that of other atomic standards. Calibration in terms of a primary standard is required. The long-term stability in this case exceeds that of the best quartz crystal oscillators by two or more orders of magnitude without the need for long warm-up or stabilization periods.
However, on a qualitative basis it may be stated that rubidium gas cell frequency standards are, at the present time, the most compact, light weight atomic oscillators, and they have a high level of short-term stability. The comparison of the different types of atomic frequency standards is complicated by the many quantitative factors relating to performance and physical characteristics which differ in each case. Modern atomic frequency standards produced in the United States are illustrated, and performance data reflecting the present state of the art is presented. A qualitative discussion of underlying principles is also included. The survey reviews the historical background and development of atomic frequency standards leading to the most recent achievements. VNIIFTRI and the VNIIM were the first to establish a united time, frequency and length standard. VNIIFTRI's work on international laser standard frequency comparisons and absolute frequency measurements contributed greatly to the adoption by the CIPM of a highly accurate value for the He–Ne/CH4 laser frequency. For many years, VNIIFTRI was the only world laboratory that applied hydrogen-maser clock ensembles for time-keeping. The milestones along the way have been the ammonia and hydrogen masers, primary caesium beam and fountain standards and laser frequency standards.
This brief review presents the main developments and studies in time and frequency measurement, and the improvement of accuracy and atomic time-keeping at the VNIIFTRI-the National Metrology Institute keeping primary time and frequency standards and ensuring unification of measurement. Some special limited edition art prints including a new exploration of the SKX and Speedmaster “Moonwatch”.Time metrology in Russia in the second half of the twentieth century has been marked, as in other advanced countries, by the rapid development of time and frequency quantum standards and the beginning of atomic time-keeping. Expect a continuation of art prints of classic wristwatches as well as horology themed art prints. What can we expect from this new collection?Ī more minimalist range of T-shirts with subtle yet hopefully still recognisable references to iconic wristwatches. Compared to 2018, there seem to be a lot more horology prints and T-shirts available now, so I feel the time is right. I've now got so many ideas swimming around in my head it feels a little cluttered and I need to unload. Why is now the right time to further extend this collection? Your horology range of t-shirts initially started in 2018 and since then has grown into many unique designs over t-shirts and posters. (So, I am eager to tick these off the list.) I'm also inspired by the subtleties in iconic watches and what makes them recognisable. I have a list of watches that I haven't yet touched on and it keeps getting bigger. So far, I've referenced just a small number of iconic watches. What was the inspiration behind your new horology pieces? The New UCHI Horology T-Shirts - Image Credit: WatchGecko Online Magazine
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