Terahertz application notes
What the calculators are doing, and where each method quietly gives a wrong answer. Written for people running the measurement, not for people buying one.
Refractive index and absorption from a THz-TDS measurement
How the standard thick-slab extraction works, what it assumes, and the four places it quietly gives you a wrong answer: etalons, phase unwrapping, the noise floor and thin samples.
Read it →Choosing an electro-optic crystal for a target bandwidth
GaP, ZnTe, GaSe and BBO compared honestly. Why velocity mismatch, not material quality, sets your detection bandwidth, and why a thinner crystal is usually the right answer.
Read it →Organic crystal thickness: why thicker stops helping
DAST, DSTMS, OH1 and BNA. Coherence length, terahertz absorption and pump absorption each cap the useful thickness, and the third one is the one most often left out.
Read it →Dynamic range, and where your data stops being data
Bandwidth claims mean nothing without a dynamic range to go with them. How to measure the noise floor honestly, why averaging buys less than you expect, and how to read a spectrum that has run out.
Read it →Water vapour lines and what they do to a transmission spectrum
Why atmospheric absorption lines throw spikes into a transmission ratio, why purging is the real fix, and how to reject the lines you could not purge away without also deleting your sample.
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