Search found 184 matches

by a_k
Sat Dec 06, 2014 5:57 pm
Forum: holoforum administration
Topic: Absent administrator ?
Replies: 12
Views: 11991

Absent administrator ?

Your suggestion is fine with me, holoforum will be closed on Jan 31 2015 as a place to discuss holography. Please use the remaining time to organise a new meeting place.
by a_k
Sat Dec 06, 2014 5:35 pm
Forum: holoforum administration
Topic: Absent administrator ?
Replies: 12
Views: 11991

Absent administrator ?

There was a single pm from you, holomaker, dated Nov 14, which was deleted by its author before it was read. If you want to get in touch with me, please use the forums email function.
by a_k
Wed Oct 15, 2014 9:19 am
Forum: Gallery
Topic: note on perspective
Replies: 5
Views: 3628

note on perspective

Hello Joe, That's quite an effect and a good presentation. The short sides of the tiles seem to get smaller and smaller, like a geometric series. But the diagonals show that they have the same size. The diagonals are a bit confusing to me though since they either begin or end at the corners but not ...
by a_k
Wed Jul 23, 2014 7:40 pm
Forum: Beginning Holography
Topic: Introduction/ Questions
Replies: 3
Views: 2013

Introduction/ Questions

Hello hkvietok and welcome to the forum. Holograms are, as all imaging methods using visible light, restricted to the surfaces of solid, non transparent objects for recording. For the reconstruction of a hologram you need a light source in front or behind the hologram. So, if you want to view a holo...
by a_k
Thu Jun 19, 2014 6:10 pm
Forum: General Holography
Topic: fringe monitor circuit
Replies: 11
Views: 3985

fringe monitor circuit

Thanks for clarifying the schematic, the arrow makes sense now. The data loggers fixed resolution of 40mV is not sufficient for a 500mV signal. The $59 looks a bit overpriced too. Have a look at this one with 8 analog + 14 digital I/O ports + SD card reader for data logging: http://www.ebay.com/itm/...
by a_k
Wed Jun 18, 2014 3:14 pm
Forum: General Holography
Topic: fringe monitor circuit
Replies: 11
Views: 3985

fringe monitor circuit

The problematic part with the idea of the chart recorder would be the interpretation of the recorded noise i think. The fringe monitors output signal (AC component) mainly indicates when the laser is entering a chaotic operating region, not something that would allow a meaningful interpretation abou...
by a_k
Mon Jun 16, 2014 6:48 pm
Forum: General Holography
Topic: fringe monitor circuit
Replies: 11
Views: 3985

fringe monitor circuit

Thanks for the circuit, Joe. Are you getting sufficient volume with the speaker and is it an ordinary 8 or 16 Ohm speaker?
by a_k
Sat Jun 07, 2014 6:13 am
Forum: General Holography
Topic: Foreign Languages of PDFs
Replies: 9
Views: 2620

Foreign Languages of PDFs

For some of the papers the main problem is that the text is skewed on the page. Rotating it so the text lines get horizontal gives much better chances that the OCR processing is successful. But then there are also other files where it really is difficult to even read. No matter how it is done, it is...
by a_k
Sat Jun 07, 2014 4:19 am
Forum: General Holography
Topic: Foreign Languages of PDFs
Replies: 9
Views: 2620

Foreign Languages of PDFs

You are welcome. I just made a test with one of the files with bad quality and the result was unreadable. Maybe there are better OCR programs around or the recognition quality of tesseract could be improved with appropriate options. I'll research somewhat further. If you find something that we could...
by a_k
Sat Jun 07, 2014 3:49 am
Forum: General Holography
Topic: Foreign Languages of PDFs
Replies: 9
Views: 2620

Foreign Languages of PDFs

I made a test with http://holoforum.org/data/lippmann/Lippmann_Photo_interferencielle_1906.PDF The program gs was used to convert it to .tif files, one per page One of the tif files was converted into text with the open source OCR program tesseract, which is able to process the images in a language ...