Handbook for KECK - ece.neu.edu fileTable 1 signal interface connector ... (IMAQ) card 1408, one NI USB-6341 Data Acquisition board (DAQ), several NI USB-6008 Data Acquisition boards

Handbook for KECK

---- Control System

Version: 2.1.1

June 25, 2014

This work is contributed by Zhenhua Lai, Zetong Gu,

Stephen Karasek, James Mclean

Documented by Zetong Gu

Supervised by Charles A. DiMarzio

Handbook for KECK-----Scanning Control System

Contents

Figures and Tables .................................................................................................. 2

1 Overview .............................................................................................................. 4

2 Control System’s Layout ..................................................................................... 5

3 The Structures of control scanning system .......................................................... 7

4 Power Supply Board .......................................................................................... 10

5 Galvo Control Board .......................................................................................... 12

6 Polygon Control Board ...................................................................................... 15

7 Sensor and Filter ................................................................................................ 18

8 Cable connection in Scanning System ............................................................... 22

Figures and Tables

Figure 1 Layout of KECK control system ............................................................. 5

Figure 2 Scanning System Structure ...................................................................... 7

Figure 3 Photo of Power Supply Board ............................................................... 10

Figure 4 function illustration of power supply .................................................... 11


Figure 5 photo of galvo control board ................................................................. 12

Figure 6 photo of interface connector .................................................................. 13

Figure 7 Vsync signal (top) and Galvo control signal (bottom) .......................... 14

Figure 8 Photo of Polygon Control Board ........................................................... 15

Figure 9 illustration of Polygon Control Board ................................................... 16

Figure 10 Instruction of connecting signal cable to polygon ............................... 17

Figure 11 sensor cables connection ..................................................................... 18

Figure 12 illustration of sensor cables connection ............................................... 19

Figure 13 the principle of the filter ...................................................................... 19

Figure 14 the result before (yellow) and after (blue) filter .................................. 20

Figure 15 Hsync (square wave) and APD signals ................................................ 21

Table 1 signal interface connector ....................................................................... 12

Table 2 Digital Control for Pin 4 ......................................................................... 16

Table 3 Keck Cable Connections ......................................................................... 22


1 Overview

The Keck 3D fusion multi-modal microscope (3DFM) in the Optical Science

Laboratory (OSL) at Northeastern University was first built by Daniel J. Townsend in

2004. The 3DFM allows us to image samples with multiple modalities on the same

stage. The modalities on the 3DFM include: Brightfield Microscopy, Differential

Interference Contrast Microscopy (DIC), Epifluorescence Microscopy (EFM),

Confocal Reflectance Microscopy (CRM), Confocal Fluorescence Microscopy (CFM),

Multi-Photon Fluorescence Microscopy (MPFM), and Second Harmonic Generation

(SHG). An imaging spectrometer is integrated in the 3DFM for spectrum measurement.

The 3DFM underwent a major upgrade in the year 2013. This upgrade to 3DFM

2.0 was led by Zhenhua Lai and assisted by Zetong Gu, Stephen Karasek, and James

Mclean. The whole control system and part of the optics were redesigned. The

performance of the second generation 3DFM has been significantly improved after the

upgrade.


2 Control System’s Layout

The control system’s layout of the KECK system is demonstrated in Figure 1.

Figure 1 Layout of KECK control system

The KECK system consists of two computers: a 64 bit Windows 7 PC and a 32 bit

Windows XP PC., one Image Acquisition board (IMAQ) card 1408, one NI USB-6341

Data Acquisition board (DAQ), several NI USB-6008 Data Acquisition boards (DAQ)

and a branch of optical parts as well as a few cameras.

The Windows XP PC is used due to incompatibility issues between the image

acquisitions cards and the Windows 7 system. The Windows 7 computer controls the

motorized rack through RS 232 port, and the grating (SP2150, Princeton Instruments) ,


the NI USB-6341, Thorlabs camera as well as NI USB-6008 through USB.

The subsystem in the red rectangle is a 2-D scanning system which makes the laser

to scan in two dimensions. The Polygon and galvanometric mirror scanner (Galvo) are

responding for one dimension separately. The NI USB-6341 controls Polygon and

Galvo to let them worked together by sending the HSync, VSync, and PCLK. IMAQ

1048 receives the picture signals and sync signals.

Hsync, Vsync and Pclk are signals to control the acquisition processing. (For more

information about sync signal, please refer to NI-Tutorial-3020.pdf and

NI-Tutorial-4750.pdf in reference folder)


3 The Structures of control scanning system

Sensor

PCLK

Vsync

Control

Signal

Hsync

IMAQ1408

NI 6341

Polygon

Reference

Signal

Galvo

Filter

Galvo

Control

Board

Polygon

Control

Board

Power Supply Board

Figure 2 Scanning System Structure

NI 6341: The NI USB-6341 is a data acquisition device as well as a programmable

signal generator that contains 16 16-bit analog input channels, 2 16-bit analog

output channels, 24 digital I/O lines, and 4 32-bit counter/timers for pulse-width

modulation. The NI USB-6341 receives real-time input laser power signal from the

power meter in analog form, and then converts and sends the sync signals to the

Windows 7 PC. A 356.7 Hz square wave signal is generated by the NI USB-6341

for controlling of the polygon mirror scanner running at a speed of 200 RPS. The

polygon mirror scanner contains 32 facets, and therefore multiplies the scanning

speed to 6.4 kHz. The polygon mirror scanner sends a Start-of-Scan (SOS) Signal

at the beginning of each optical scan. For generation of the SOS signal, a red LED


is placed close to the polygon mirror. The reflected red light is detected by two

closely placed photodiodes. The SOS signal is the differential signal of the two

photodiodes. The SOS signal is then processed by a bandpass filter, and turned into

6.4 kHz square waves, which is served as triggers for the NI USB-6341 to generate

HSync, the signal that synchronizes each horizontal line of an image. The HSync

also serves as the trigger for NI USB-6341 to generate VSync, the signal that

synchronizes the acquisition of each image, pixel clock (PCLK), the signal that

synchronizes the acquisition of each pixel, and the control signal that controls the

galvanometric mirror scanner. Note that a pseudo-sawtooth is used in 3DFM 2.0,

which is different from the old 3DFM. The control signal of the galvanometric

mirror scanner will be discussed later.

IMAQ 1408: The NI IMAQ PCI 1408 is a 4-channel image acquisition module

that converts analog signals into 8-bit grayscale images. The NI IMAQ PCI-1408

is connected to the Windows XP PC through a PCI slot. The following detectors

are connected to the four acquisition channels of NI IMAQ PCI-1408: CFM PMT,

CRM APD, forward SHG PMT, and MPFM or backward SHG PMT. Since each

NI IMAQ PCI-1408 contains only one A-D converter, only one channel can be

running at a time. However, multiple modalities can be taken simultaneously by

utilizing multiple NI IMAQ PCI-1408s. The number of channels is limited by the

number of PCI slots in the computer, as well as the computer resources. An

alternate solution is running different channels alternatively. e.g. we can acquire

CRM and MPFM images alternatively. Since the image acquisition time is 0.1 s,


the interval between the two modes is 0.1s, which results in a two-modal

acquisition at a frame rate of 5 frame/s. The above solution is referred to as

pseudo-simultaneous mode.

Power Supply Board (Charper4)：Provide the power to Polygon and Galvo.

Galvo Control Board (Charper5)：Control the position, speed, etc. of the Galvo.

Polygon Control Board (Charper6)：Control the speed of Polygon.

Sensor (Charper7)：Detect the position of Polygon and generate Hsync through

the filter.

Filter (Charper7): Change the Hsync signal from analog to digital. In order to be

received by NI 6341.


4 Power Supply Board

This board is the power supply of the Polygon, Galvo, APD, and the main control

board. Figure 3 display the photo of power supply board. Figure 4 demonstrates the

function and volts for each pin.

Figure 3 Photo of Power Supply Board

The red rectangle is designed for old control board which comes into disuse.

However the pins can still work so that those 5 pins can be used as others function.

The green one is designed for Galvo mirror control board. The blue rectangle is the

power source for polygon while the yellow one is used for APD to acquire CRM

image.


POWER SUPPLY BOARD

Old Control Board

Galvo

NC

+1

5V

-1

5V

GN

D

NC

+15V

GND

-12V

+12V

+4.8V

Polygon

+2

4.5

V

GN

D

APD

+1

2V

GN

D

-1

2V

Figure 4 function illustration of power supply


5 Galvo Control Board

Figure 5 photo of galvo control board

The control signal interface is provided on connector J2 located on the baseboard.

System I/O including command input, position output, status feedback, and enable are

located on this connector.

In practice, we only use the pin1, 2 and 3. Connect the pin2 and pin3 together to the

Ground. A 8-pin cable connect the control board to NI USB-6341.

Table 1 signal interface connector


Figure 6 photo of interface connector


Figure 7 Vsync signal (top) and Galvo control signal (bottom)

(For more information about Galvo Control Board, please refer to “Galvo

controller.pdf” in reference folder)


6 Polygon Control Board

This board is the control board of polygon. A 356.7 Hz square wave signal is

generated by the NI USB-6341 for controlling of the polygon mirror scanner running

at a speed of 200 RPS. The polygon mirror scanner contains 32 facets, and therefore

multiplies the scanning speed to 6.4 kHz.

Figure 8 display the photo of polygon control board and Figure 9 demonstrates

the function for each pin.

Figure 8 Photo of Polygon Control Board


POLYGON CONTROL BOARD

Connect to Polygon

Power

Supply

Board

+2

4.5

V

GN

D

Pin1 Reference Frequency Input

Pin4 Enable

Figure 9 illustration of Polygon Control Board

In practice, two pins are used for control the polygon. Pin1 is the reference

Frequency input which enables us to control the speed of polygon, while Pin4 is the

enable pin. The control value is showed below:

Pin1:

Control the speed of the polygon. We may use square wave.

Pin4:

Table 2 Digital Control for Pin 4

Pin value function

0/GND Enable


1/5V Unable

Figure 10 Instruction of connecting signal cable to polygon


7 Sensor and Filter

The mainly function of this part is generate the Hsync from the Polygon. The

polygon has 32 faces, hence the Hsync signal has 32 periods when it rotates one circle.

The polygon mirror scanner sends a Start-of-Scan (SOS) Signal at the beginning of

each optical scan. For generation of the SOS signal, a red LED is placed close to the

polygon mirror. The reflected red light is detected by two closely placed photodiodes.

The SOS signal is the differential signal of the two photodiodes. The SOS signal is then

processed by a bandpass filter, and turned into 6.4 kHz square waves, which is served as

triggers for the NI USB-6341 to generate HSync, the signal that synchronizes each

horizontal line of an image.

Figure 11 sensor cables connection


Power

Supply

Connect to LED

+Vcc(3.2V-3.8V)

Photodiode Output 1

Photodiode Output 2

Photodiode Output 3

Figure 12 illustration of sensor cables connection

Output 1 and Output 2 is used for generate the Hync single. The filter will change

the Hsync signal from analog to digital and eliminate the noise.

The principle of this process shows below:

Photodiode Output 1

Photodiode Output 2

Photodiode Output 3

1k

Input_A

Input_B

A

B

A-B

TTL out

Figure 13 the principle of the filter

In practice, put output1 and output2 into CH1+ and CH1- of the filter. Use the Diff

mode in CH1. (CH1: Low pass 150K Hz. Input Gain:50, Output Gain:0). Put the output

of CH1 to CH2 input. (CH2: High pass 10 Hz. Input Gain:50, Output Gain:0). Put the


CH2 into NI 6341 for Hsync. The input gain can change according to the different

situation. Figure 14 demonstrate the single before and after the filter. Figure 15

display the Hsync single which is the same as the blue single in Figure.14. Also, the

APD single is showed on Figure 15 for future testing convenience.

Figure 14 the result before (yellow) and after (blue) filter


Figure 15 Hsync (square wave) and APD signals


8 Cable connection in Scanning System

The cable connection instruction showed here for future maintenance. Shielded

twisted pair cable is used here in order to eliminate the noise. All the ground as well

as mental case of instruments should be connected together.

Table 3 Keck Cable Connections

Device1 and Pin Device2 and Pin Type&Note

6341 pin15(AO 0) Galvo + pin1

Shielded Twisted Pair

6341 pin16(AO GND) Galvo – pin2

6341 pin31(AO 1) 1408 pin19(Vsync+)


6341 pin32(AO GND) 1408 pin6(Vsync-)

6341 pin89(P2.4) Polygon pin1 (REF)


6341 pin88(D GND) Ground

6341 pin73 (P1.0) Polygon LED in One Shielded Wire

6341 pin91(P2.5) 1408 pin18(Hsync+)


6341 pin90(D GND) 1408 pin5(Hsync-)

6341 pin95(P2.7) 1408 pin17(Pclk+)

Shielded Twisted Pair 6341 pin94(D GND) 1408 pin4(Pclk-)

Documents

Handbook for KECK - ece.neu.edu fileTable 1 signal interface connector ... (IMAQ) card 1408, one NI USB-6341 Data Acquisition board (DAQ), several NI USB-6008 Data Acquisition boards