## the Fabry-Pérot resonator

Calculate the transmitted or reflected intensity and phase for a Fabry-Pérot cavity. Both reflectivities and resonator losses are accounted for.

reflectivity 1: %

reflectivity 2: %

cavity round-trip loss (power): %

transmissionreflection

Fig. 1: normalized intensity vs. round-trip phase [rad]

resonator finesse:

### FM and PM Modulation Spectrum (interactive)

This little widget will calculate the spectrum for various modulation signals with arbitrary frequency and amplitude and explain why it looks the way it does.

### Bokeh calculator (interactive)

If you don’t want to do all the math in the the math of bokeh post yourself, you can just enter your data into this here little applet and get your results much quicker.   bokeh (disk) size: 0mm relative bokeh size: 0% (as fraction of sensor height)

### the math of bokeh

If you don’t know (yet) what bokeh is, check out the Wikipedia article. In short, bokeh is the blur (or quality thereof) of out-of-focus regions in a photograph. This post is not about the perceived quality of such blur, but rather of its size. For bokeh, more is usually better, since it allows to separate […]

### Microsoft Project Lessons

Here are some tips for using MS Project in particular and project management in general that I picked up, which have either proven useful or which sound reasonable and which I plan to try out in the future. Feel free to add yours in the comments. Leave Buffers Since no project ever goes according to […]

### Adventures in JavaScript: Number Bases

Here’s just a quick little JavaScript that will convert numbers between different bases. It grew out of the idea that numbers in a system based on π would be much more useful in engineering that the regular old ones. Well, just because one can do it doesn’t mean it’s a good idea, but it was […]

You thoroughly air out your rooms during winter time and watch the humidity inside drop in the process (provided you own a hygrometer). But where will it stop? This little gadget will tell you. Just enter the outside temperature and humidity and the temperature the air will be heated up to inside.   References [1] […]

### Paraxiality

The previous post on the Gaussian beam noted that this beam is a solution to the paraxial wave equation and thus only accurate for small divergence angles. The limit given in [1] was $w_0 \gt 2\lambda/\pi$ or $\theta \lt 0.5\mathrm{rad}$ or $\approx 29^\circ$. The Gaussian beam model is of course not exact up to that […]

### the Gaussian beam (interactive)

The Gaussian beam “is a convenient, widespread model in laser optics.” [1] It is indeed convenient that such a mathematically relatively simple model can describe the evolution of laser light in free space so well. Given the wavelength of the laser, it can be described by a single parameter. This can be either the beam […]

### TiddlyWiki – EditSectionPlugin Keyboard Shortcuts

Like so many of his plugins, Eric Shulman’s EditSectionPlugin for TiddlyWiki is quite awesome. Especially in long tiddlers it can save you a lot of scrolling and searching. One thing I was missing, though, were the keyboard shortcuts ESC to cancel editing and CTRL+ENTER to finish editing, like the ones you have when editing the […]