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Comment Bresser Biolux NV 20x-1280x Microscope (Score 1) 118

I bought this upright microscope for a 9 year old: Biolux NV 20x-1280x Microscope, she loved it!

It has a USB ocular which Linux recognised straight away. Feels nice and solid, with only a tiny bit of hysteresis on the adjustment knob. Nothing a child couldn't cope with.

Optics are surprisingly good quality and the light sources use a little mains adapter, which is included. No batteries required!

There are also a few sample slides included with the microscope, but Bresser sells stained slide kits separately, these might be worth exploring, not sure.

Anyway, check the reviews, I thought it was a terrific microscope for a kid.

Comment Re:$225,000 (Score 1) 216

Hiya, thanks for taking the time to answer my comment!

I'm in the process of building a multiphoton microscope (donated axiovert 135 body and Hamamatsu detectors). Of course, I have nowhere near the amount of money to buy a Ti:Sapphire and would much rather spend the money on good IR lenses and upgraded optics.

I've been looking at "alternatives" in the form of Ytterbium based lasers for the reasons you describe: small 2 box footprint (with a pulse picker), integrated solid-state pump and no cavity tuning (or so the manufacturer says). Other advantage is the reduced photodamage with a two photon excitation around the 1030nm mark, but I am still waiting for an answer on the expected second harmonic / third harmonic signal generation efficiency (probably something I won't find out for certain until the entire microscope is built). 1-5% for THG seems frighteningly low, but fortunately, the detectors I'll be using have low dark count.

Also the 5nJ per pulse spec from the manufacturer worries me slightly. One thing I haven't quite worked out from the available literature is the discrepancy between the available energy (say 60-100nJ per pulse from a Yb:KGW laser) and the energy deposited on the sample (around 1nJ per pulse, when mentioned). I hope the loss comes from using a neutral density filter and not from losses due to the microscope optics...

With the right skills of course, the whole process of building your own microscope seems easy enough :-)

Comment Re:Hubble? I don't think so (Score 3, Interesting) 149

One amateur reprocessed images from Soviet Venus landers and brought out some amazing detail, finding landscape features that weren't spotted before. It's simply the case that sometimes amateurs are simply motivated to spend the necessary time and attention to detail more so than "professionals", who normally have full in-boxes. Amateurs can decide to be as anal as they want. Call it open-source astronomy.

Thanks! I looked it up, and if you are referring to Don Mitchell's story, it is indeed well worth reading.

Even better, the re-processing pipeline for each of the Venera mission datasets is explained in great detail. For instance, about the Venera-9 mission images (from

The upper image is the raw 6-bit telemetry, about 115 by 512 pixels. Automatic gain control and logarithmic quantization were used to handle the unknown dynamic range of illumination. Previously published images from these probes suffered from severe analog generation loss, so it is fortunate that the original data was found. The raw image was converted to optical density according to Russian calibration data, then to linear radiance for image processing. It was interpolated with windowed sinc filter to avoid post-aliasing (a "pixilated" appearance), and the modulation transfer function ("aperture") of the camera was corrected with a 1 + 0.2*frequency**2 emphasis. This was then written out as 8-bit gamma-corrected values, using the sRGB standard gamma of 2.2. Some of the telemetry bars on the right were replaced with data from the 124 panorama. The bottom image is digitally in-painted, using Bertalmio's isophote-flow algorithm, to fill in missing data.

... and for a BBC coverage of the story:

Comment Re:Strange pulse stories (Score 1) 329

In the dual-chip system, the microcontroller doing the AD conversion + filtering might be advantageously replaced with something purpose made. The chip on this page looks really excellent:

The measurement results showed that the circuit performs as expected and it achieves a CMRR of 82 dB and a maximum SNDR of 36.1 dB with 1-V supply voltage. The total current consumption of the chip, including the output buffer, is only 3 A. Furthermore, the average current consumption of the 8th order bandpass SO-SC filter is very low, since it consumes only about 400 nA, corresponding to 50 nA/pole, which is much less than the current consumption of the SC filters in prior designs. Therefore, the circuit is very suitable for portable ECG measurement applications, like heart rate detectors.

Not sure if anything like this is available commercially though... and of course, using off-the-shelf electronics will cut the costs right down.

Comment Re:It it hadn't been for the Catholic Church .. (Score 3, Insightful) 141

Read Bachelard Formation of the scientific mind and weep. If only it were so easy and blame everything on the catholic church. For a very long period of time, it looks as if entertainment value was put way above scientific rigor... that and scientific thinking is quite a recent thing. From the book, experiment held around 1700 (from vague recollection): Electricity from a battery cell passes through a liquid and the experimenter's tongue. Experimenter then "tastes" the electricity. Taste through milk? "Soft and sweet" as opposed to electricity flowing through vinegar "strong acid taste". Anyway, interesting read.

Comment Same with a multianode microchannel plate? (Score 1) 42

Nice one! Jitter looks a bit high at 80ps but other than that, interesting concept.

SPAD afterpulsing is probably not an issue for this project because it's looking at photon pairs, so uncorrelated random events occurring on all the SPADs won't affect the detection... but will decrease the counting/processing rate by bogging down the electronics.

For measuring concurrent events, I would've thought TTS would be much more critical, and you can't get much better than MCP-PMTs (10-20ps these days?). Just wondering if the same detection could've been done with a multi-anode MCP, although if the sensor is CMOS tech, APDs would probably be easier to incorporate onto an ASIC / SoC.

Book Reviews

Linux Firewalls 91

David Martinjak writes "Linux Firewalls, authored by Michael Rash and published by No Starch Press, covers five main topics: traditional packet filtering with iptables, port scan detection, snort rule translation, port knocking, and log visualization. At first I considered only skimming the chapters regarding iptables packet filtering. I have a good amount of experience with iptables, and have been running it for several years. Thankfully I decided to give the first chapter a good read. Right from the start, the book presented valuable information and pulled me in." Read on for the rest of David's review.

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