ElectroHolography Laboratory

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===== Manusha Korimi =====

(+13852688862)

manushamudhiraj@gmail.com

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What is a resonant scanner?
A resonant scanner is a fixed frequency oscillating mirror with an adjustable scan angle.
The device high "Q" (very low damping) provides perfect sinusoidal oscillations at the resonant frequency and very low electrical drive power.
The long life scanner is jitter free and maintenance free.
Position output is available with the AGC type driver.
Velocity output is available with the AGC type driver.
Where are resonant scanners used?
Resonant scanners are used in the range from X-Ray across to Far-IR, in the lab and in the manufacturing industry and also in high vacuum and cryogenic environment. The scanners are used in industrial, scientific, medical, aerospace and military applications worldwide. 

What are resonant scanners especially suitable for?
Resonant scanners are especially suitable for:
- Applications which require good imaging with minimal distortion.
- Dedicated application, high volume, OEM instruments and systems.
- Long operation life.
- Jitter free and maintenance free operation.
- Small instruments that require a miniature scanner structure for hand held and portable instruments.
- Use in vacuum or cryogenic environment and/or from X-Ray across to Far-IR.
- X,Y scanning systems.
- To meet military specifications.
- For aerospace use.

The type of optical resonator which fulfills our purpose is SC-5.

{{:sc-5a_o.jpg?200|}}

Model SC-5: low cost sub-miniature Optical scanner

There is another variant in SC-5:
SC-5  This is the one which we are going to use
SC-5-HF (for high frequency)
Specifications of SC-5:
Mirror size: 6mm dia, 6x6mm, 7x7mm & 10x10mm 
Scan angle: to 50 P-P degrees optical
Frequency: one FIXED frequency from the range of 100Hz to 2200Hz.
The SC-5 type sub-miniature fixed frequency resonant optical scanners are electromagnetically driven moving mirror device, which deflects a light beam with a sinusoidal motion. The mirror assembly is attached at the center of a torsion spring. <fc #ff0000>WAIT!</fc>
<fc #6495ed>What is torsion spring?
A torsion spring is a spring that works by torsion or twisting; that is, a flexible elastic object that stores mechanical energy when it is twisted. When it is twisted, it exerts a force (actually torque) in the opposite direction, proportional to the amount (angle) it is twisted.</fc>

{{:torsion_spring.gif?300|}}

<fc #6495ed>The above image is in GIF format.</fc>

So the torsion spring present beneath the mirror plays a pivotal role in its deflection.
{{:sc-5_o.jpg?300|}}
The scanning frequency range of the SC-5 type scanner is from 100 Hz to 1500 Hz, fixed at any one value within the range.
<fc #6495ed>What is scanning frequency?
Scanning Frequency is the ability of how frequently it scans the incoming signals. The scan angle is inversely proportional to the frequency, and is a function of the mirror size.</fc>
<fc #ff0000>WAIT!</fc>
<fc #6495ed>What is scan angle?
The angle to which the mirror deflects when the laser beam hits it is called Scan angle.
Why is the scan angle inversely proportional to the frequency?
The scan angle is inversely proportional to frequency, is due to the fact that, the higher frequency waves have very less wavelengths, the angle to which they deflect the mirror might be relatively small. (This is just an assumption).</fc>
The standard operating temperature is 0°C to +65°C. Other temperature range and vacuum operation are available upon request.
High device "Q" insures frequency stability, low reaction forces and low electrical drive power.
<fc #6495ed>What is Q?
The Q, quality factor, of a resonant circuit is a measure of the “goodness” or quality of a resonant circuit. ... A practical application of “Q” is that voltage across L or C in a series resonant circuit is Q times total applied voltage.
For further information on Q:
http://www.electronics-tutorials.com/basics/q.htm</fc>
High flexural stiffness provides good resistance to shock and vibration, as well as low wobble, and good scan repeatability.
<fc #6495ed>What is Flexural stiffness?
Flexural rigidity is defined as the force couple required to bend a non-rigid structure in one unit of curvature or it can be defined as the resistance offered by a structure while undergoing bending.
Resonating at the natural frequency makes the device an excellent candidate for long life operation for a multitude of applications which require good imaging with minimal distortion. The scanner is especially suitable for dedicated, high volume, OEM industrial applications. The SC-5 type scanner can easily be incorporated in small size and portable instruments.</fc>
Operation at resonant frequency is sustained by a feedback amplifier type ED driver or the AGC driver, using the scanner as a frequency source. The AGC driver also provides a higher amplitude stability (0.01%) and a position output signal. The PLD-1S driver phase locks the scanner to an external clock signal. The PLD-2S driver locks two scanners of the same frequency in a Lissajous pattern to create a circle or an ellipse or to lock two resonant scanners of the same frequency in phase or out of phase. The PLD-2SXY driver locks two resonant scanners to generate a raster scanning system. The PLD-XYG driverlocks a resonant scanner (high frequency) with a galvanometer (low frequency) to generate an X,Y raster scanning system.
Applications include: image and pattern forming and recognition, data acquisition, confocal microscopy, ophthalmoscopy, biomedical imaging, mask imaging, quality inspection and outer space and environmental research to name a few.

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SPECIFICATIONS:
SCANNER:
SC-5 size (in inches): 01.00 x 0.63 x 0.46 
Scan frequency range: 100 Hz to 1500 Hz
Frequency accuracy: +/-2% at 25°C, closer accuracy available upon request
Scan angle: to 50° peak to peak optical as a function of frequency and mirror size.
Scan frequency range: 100 Hz to 1500 Hz
MIRROR:
Size: up to 10×10mm, as a function of frequency; larger size available
Thickness: 1.0mm, standard; other thickness values available
Flatness: 1/4, 1/2 and 1 wavelength as a function of size
Surface quality: scratch and dig: 60-40
ELECTRICAL:
Drive coil resistance: 150 or 400 ohms as a function of frequency
Sense coil resistance: 950 ohms
Connector: female 4 pin plug on 0.1 inch centers, Molex P/N 22-01-3047 or equiv.
Power supply guidelines:
http://www.eopc.com/sc5.html.imhbak.2010-02-02

When the input of 12V DC is given as input to SC-5, the mirror has started deflected which can be seen in the images and video below:

{{:sc-5_video.mp4|}}

{{:sc-5e_o.jpg?300|}}

It can be seen in the photograph that, a number (95 Hz) is written on the black case on which the entire device is mounted. It depicts that the mirror deflects at the frequency of 95 Hz.

When the output of SC-5 was verified on the oscilloscope, the following results were observed

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{{:sc-5c_o.jpg?300|}}

{{:sc-5d_o.jpg?300|}}

After measuring the rate of electrons which run through SC-5 to oscillate the mirror on it, the following results were obtained:
 
{{:sc-5_current_1.jpg?300|}}
                                         
The driver of SC-5 was connected to the multi-meter according to the below circuit:
{{:sc-5_current_1_circuit.jpg?300|}}
                                         
I have connected the SC-5 to the multi-meter according to the below circuit and found out that, the current flowing through the SC-5 is still the same:

{{:sc-5_current_2_circuit.jpg?300|}}
                                      
The below photograph shows that, the SC-5 was connected to the multi-meter according to the circuit shown above:

{{:sc-5_current_2.jpg?300|}}
                                      
The power of SC-5 was calculated as follows:

     Power= Voltage*Current through the SC-5
     
     Power= 12*0.0306 = 0.3672 Watts
     
(Current was measured in milliamperes)

1)To convert the signals from GPU to acoustic.
2)And incident these acoustic signals unto Lithium Niobate also known as wave guide
3)Pulse the laser beam on the surface of the wave-guide whose surface has dents as defined by the acoustic signal
4)Synchronize the reflected laser light from the waveguide with the oscillation of the resonant scanner
5)The oscillating resonant scanner reflects the light which is incident on it unto a transparent sheet which will      be our eyeglasses
 
But before converting the signals from GPU to acoustic, GPU must be connected to G-Sync.

What is G-Sync?
Sometimes, when your GPU/graphics card and monitor are out of sync, and the GPU sends a frame in the middle of a monitor’s refresh rate, the monitor ends up drawing parts of multiple frames on the display at the same time.

This can result in visually discernable artifacts known as “tears,” or tearing; a form of distortion where objects on the screen appear to be out of alignment.
You can keep your GPU and monitor in sync by enabling vsync, which causes the GPU to send frames to the screen in sync with the monitor’s refresh rate (usually at 60Hz, or 60 times per second). However, while maintaining sync via vsync eliminates tearing, it can introduce yet another artifact called “stuttering,” as well as input lag.


The good news is that Nvidia’s G-Sync monitor technology eliminates the tear, stutter, and input lag phenomena that plagues many PCs.
So, what is Nvidia G-Sync exactly?

G-Sync is a hardware-based tech that manipulates the display panel’s vertical blanking interval (VBLANK). VBLANK represents the interval between the time when a monitor finishes drawing the current frame, and the beginning of the next frame.
During this interval, no screen refresh data is sent to the monitor. When G-Sync is active, the graphics card in your PC waits until the monitor is ready to receive another frame before sending it. This keeps everything in sync, and eliminates annoying and distracting visual artifacts.


A G-Sync board contains 768MB of DDR3 memory, which stores the previous frame so that it can be compared to the next incoming frame. It does this to decrease input lag.
G-Sync allows a monitor to support variable refresh rates, which are often redrawn at widely varying intervals. Syncing the GPU and monitor’s refresh rates helps make in-game animations appear smoother.

What is H-BLANK and V-BLANK?

H-BLANK: is the time in which the GPU writes black pixels before it reaches next line on the monitor to draw the line (in order to fulfill the objective of drawing the entire frame)

V-BLANK:is the time the GPU takes to reach to the first pixel on the first line from the last pixel on the last line (after it completes drawing the current frame) in order to start drawing the next frame.

G-Sync is capable of reducing this V-BLANK time in order to provide the smoothness in the game flow.
ElectroHolography Laboratory

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