Quantum Tao

interpreter

(most interpreted programs are referred to as scripts, interpreter is called “script engine”)

VB.net/Java (virtual machine or a runtime)

compiler

procedural, structured, and object-oriented programming

OOP: the essence of OOP is to model “objects” rather than “data”

3 pillars of OOP” encapsulation (the property of being a self-contained unit), inheritance, and polymorphism(the same thing taks many forms)

C++ and Java: very similar

C#: for the .NET platform, the same syntax as C++

Development environment:

console, IDE

the source files, extension: .cpp, .cp, or .c

use a compiler turn source code into a program, extension: .obj or .o

then link object file with any needed libraries to produce an executable program

The hello world:

#include <iostream>

int main()

{

std::cout <<”hello world!\n”;

return 0;

}

Same thing in Perl:

#！/usr/bin/perl

print “hello world\n”;

#:pound/sharp/hash

Building hello world project in Visual C++6:

1, start the compiler

2, choose file, new from the menus

3, choose win32 console application and enter a project name, such as hello, click OK

4,choose an empty project from the menu of choices and click FINISH. A dialog box is displayed with new project information

5 ,click OK.

6, choose File, New from the meus

7,choose c++ source file and give it a name, such as hello. enter this name into the File name text book

8, click OK

9, enter the code

10, choose Build, build hello.exe from the menus

11, run the program by pressing Ctrl+F5 or by selecting Build, Execute hell from the menus

12, press the space bar to end the program

基本控制结构

1, 根据条件判断执行 condition

if/unless
if ($num < 5) {
$num++;
}
$num++ if ($num < 5);
else/elsif

2，重复执行 loop

while/until
my $num = 1;
my $result = 1;
while ($num <= 10) {
$result*=$num;
$num = $num + 1;
}
my $num = 1;
my $result = 1;
until ($num > 10) {
$result*=$num;
$num = $num + 1;
}
for
my $result = 1;
for (my $num = 1; $num <= 10; $num = $num + 1) {
$result *= $num;
}

简单的写法：

for my $num (1…10) {
print $num;
}

for (1…10) {
print $_;
}

print for (1…10);
foreach

(more…)

串列与阵列（list/array)

在perl中， 阵列变量 array以@开头。定义 @array， 用$array[0], $array[1]… 来存取阵列元素。

赋值： my ($array[0], $array[1], $array[2]) = qw/first second third…./;

my @array=(0…10) ;

直接利用串列赋值给阵列： my @array = qw/first second third/;

在perl里，不需要在程序开始定义阵列长度。

$#array+1:阵列中元素的数目 (more…)

There are some optics lab notes online from University of Colorado.

In the laser cooling and trapping note, the simple version of laser frequency version was introduced.

some thoughts:

dither locking is different from PDH locking; laser frequency stabilization is based on the generation of a frequency error signal, which passes through zero at the lock frequency.

side locking and peak locking; a disadvantage of side locking is that fluctuations in beam alignment and intensity will alter the lock point and cause a drift in the laser frequency.

A disadvantage of the dither locking method is that the output of the laser is modulated directly, or that expensive electro-optics components must be used to modulate only the light entering the saturation absorption cell. Furthermore, both peak and side-locking techniques have a limited recovery range, since the resonance peaks are very narrow.

In our setup, frequency modulation in done by dither (fast modulation) the laser current, not the PZT. It uses saturation signal to detect laser frequency and a feedback loop to hold the laser cavity constant

The laser lock procedure:
First, connect the saturated absorption signal to photodiode in, Ramp raw out to laser PZT, dither out to fast moudulation, fast modulation to laser current modulation. There is another important setup: feedforward enable and feedforward gain.

The function of laser current modulation (frequency modulation) is to get the dispersion like error signal.

Next, ramp on PZT can scan the laser frequency, so we can see the saturated absorption signal. Change the ramp amplitude to
zoom in or zoom out the spectrum. Using ramp offset to move the spectrum and center the interested part on oscilloscope.

Then, zoom in to the peak you want to lock to, then turn off ramp, switch on Proportional and Integral enable and fast enable, the laser now should be locked to the peak. Make sure the error signal is zero. And make some noise, see whether the lock can stay.

Nature Photonics article about Optical Design Software:

Advanced Systems Analysis Program (ASAP) for virtual prototyping of optical systems and devices from Breault Research Organization (Tucson, USA) www.breault.com

RSoft Design Group (Ossining, USA) has released version 4.7 of its Optical Communications Design Suite, which helps optimize the design and performance of optical communication systems. The suite features two simulation packages: OptiSim for single-mode-fibre systems and ModeSYS, an accompanying version for multimode systems. The company has also released an advanced CAD system for its Components Design Suite, which covers photonics applications in the optoelectronics, communications and semiconductor industries. It works with the company’s line of passive device simulation tools, including BeamPROP, FullWAVE, BandSOLVE, GratingMOD, DiffractMOD and FemSIM. www.rsoftdesign.com

Lambda Research (Littleton, USA) has released new versions of its TracePro, OSLO and Lucid range of software packages.

Optical Research Associates (Pasadena, USA) has released version 6.0 of its LightTools software for illumination modelling, design and analysis. www.opticalres.com

Zemax from Zemax Development (Bellevue, USA) offers improved lens design, illumination, laser-beam propagation, stray-light analysis and freeform optical design.  www.zemax.com

What happens if two mirrors are arranged to face each other in empty space? It is easy to draw the conclusion that nothing will happen. But actually, there will be an attractive force that pull the two mirrors toward each other. The attractive force between two surfaces in a vacuum is called the Casimir force. It is first predicted by Hendrik Casimir in 1948 [1]. And the first convincing measurement of the Casimir force was initially made by Steve K. Lamoreaux in 1997 [2]. (more…)

Interleaver: An optical device that separates a series of optical channels so alternating wavelengths emerge out its two ports. The best known type is a Mach-Zehnder interferometer.

From Wiki:

An optical interleaver is a 3-port passive fiber-optic device that is used to combine two sets of dense wavelength-division multiplexing (DWDM) channels (odd and even channels) into a composite signal stream in an interleaving way. For example, optical interleaver takes two multiplexed signals with 100 GHz spacing and interleaves them, creating a denser DWDM signal with channels spaced 50 GHz apart. The process can be repeated, creating even denser composite signals with 25 GHz or 12.5 GHz spacing. (more…)