Optical encephalography
Model :
Spectratech OEG-16


The example of wearing



 It is an equipment to have aimed to measure the change of the amount of in vivo blood in a multi channel method simultaneously by utilizing the light absorption characteristics in the neighborhood of near infrared to red light, that changes depending on the state how the in vivo hemoglobin is combined with oxygen. The spread spectrum modulation method, that is the latest digital technique originally developed by our company is adopted for the optical modem technology that underlies this equipment. It has achieved great reduction in costs, downsizing, and high performance compared with the conventional technology.
It is assumed that this equipment is used mainly on the frontal lobe part that has few hairs. A simple and non-invasive measurement is possible. Also, it considers using it for battery-powered and moving measurement system, and simultaneous measurements for multiple subjects.
In addition, this equipment was developed only for the research purpose, therefore please refrain from any use for other purposes.
This equipment can be used in stand-alone mode, or by connecting with PC with USB port and Microsoft Windows installed.


(1) Small-sized Main unit (about half the size of a notebook PC), suitable also for mobile measurement.
(2) Dedicated design for use on the frontal lobe.
(3) Adoption of spread spectrum modulation in the latest light modulation technology.
(4) 6 light-emitting points, 6 light-receiving points, and 16 measurement points/channels.
(5) Event-related designs and block designs are available.
(6) Synchronous operation with other measurement device (TTL level input) such as triggers.
(7) Event signal input from an external device such as stimulus presentation PC (TTL level), or by manually inserted input.
(8) Signal bandwidth of oxyhemoglobin and deoxyhemoglobin: 0.76Hz (0.65sec sampling time).
(9) Real-time measurement and display with PC connected via USB port.
(10) Operation with AC input, or battery.
(11) Operation with battery only for up to 1 hour for mobile measurement.
(12) Continuous operation with AC power input for up to 10 hours.
(13) Carrying bag for mobile measurement (detachable).
(14) Simultaneous measurement by multiple units (hyper-scanning) to record multiple subjects. Up to 5 units with the optional Distributor are available.



Spectratech OEG-16-01 Head module
1) Light injection part : 6 units installed

LED with two built-in wave lengths (Wave length 1: 840nm Wave length2: 770nm)

2) Optical light-receiving part : 6 units installed

Si PIN photo diode

3) Number of simultaneous measurement channels : 16 channels
4) Distance between light injection part and optical light-receiving part : 3cm

Spectratech OEG-16 Main unit
1) Measuring method of biological signal

Based on the modified Beer-Lambert Law
Measurements of ΔCoxyHb, ΔCdeoxyHb, ΔCtotalHb

2) Optical multi-modulation method

Modulation method: Spread spectrum modulation DS (Direct Sequence) method Note 1
PN CODE: M-sequence code
Effective bandwidth of biological signal: 0.76Hz (Sampling interval: 0.65 seconds)

3) Event input function

It is possible to input manually at an appropriate time using the accessory box for manual event trigger input.

4) External trigger input function

For the ganged operation with external device, it equips two systems of  “External trigger input block” that is isolated optically.

5) Measurement time

(1) AC power supply Continuous measurement for up to about 10 hours
(2) Battery operation Continuous measurement for up to about 1 hour

6) PC-connected operation

Connecting a PC with USB port by the attached USB cable, and installing Windows and the attached Install software (CD) on the PC, it is possible to output various commands from the PC, and to send the measurement data to the PC for recording or displaying them.

7) Batteries (Not included with shipment)

For main part of Main unit : 4 x AA battery (Continuous operation for about 1 hour)
For photo isolation : 2 x AA battery (Continuous operation for about 6 months)
For internal clock : CR2032 Lithium battery (Continuous operation for about 3~5 years)

Note 1:
The DS (Direct Sequence) method is one of the spread spectrum signal generation methods, called direct diffusion method as well, and modulates by using the random number that is called spread code sequence (PN sequence).


1) Spectratech OEG-16 Main unit ——————————————————————- 1 set

Front side of Main unit
Front side of Main unit

POWER: It is the power switch. Pushing the upper part turns on the power. When the power is supplied by either of the AC adaptor or the battery and it is ready to operate, the LED on the button turns on.
START:  It is the button to start measurement/recording. Pushing the button starts measurement/recording, and the LED on the button turns on to show the start of operation. Please note that it cannot start unless the in-vivo calibration was done by CAL button, and the CAL LED turns on. If the START button is pushed again during the measurement/recording (LED lighting-up), it restarts another measurement/recording from the point when pushed again after deleting the recorded data till then. It is useful when a recording is started in spite of insufficient preparation at the time of beginning a measurement though it often happens.
STOP:  It is the button to stop measurement/recording. Pushing the button stops measurement/recording. The Green LED in the button lights to indicate the confirmation of the stop.
Multiple tasks can be measured and recorded by repeating START/STOP. Recording time of the record memory in the Main unit is about ten hours. Even if the START button is pushed, it doesn’t begin to record when the memory is full. When the memory became full, please send off the data to the PC once for processing the memory to be empty.
EVENT: The button is pushed when an event trigger is input manually from the front face of the Main unit. It reacts only when it is measuring. In addition, the manual event trigger input is prepared also on the back face of the Main unit.
CAL: It is the button for the in-vivo calibration. In case of AUTO mode described in the separate Software edition, please push the button once before beginning a measurement after installing the head module to a live body. The LED becomes in lighting state when the calibration ended, and it becomes possible to measure. It always lights in case of MANUAL mode, and it can start a recording at any time without performing the calibration work.
BATT: When the capacity of the battery (a block of four AA batteries) for the main part of Main unit fell to less than the rated value, it lights (red). In case of battery operation, please exchange the battery for charged one in good time when the LED lighted. Continuous operating time of the battery is limited in one hour. In addition, it does not guarantee one hour in operation of this equipment with batteries other than the ENELOOP of SANYO. Please use the ENELOOP without fail.

Back face of Main unit
Back panel of main unit

SENSOR L: Cable L for Spectratech OEG-16-01 Head module is connected.
SENSOR R: Cable R for Spectratech OEG-16-01 Head module is connected.
EXT-EVENT-IN 1: It is used for the start input of measurement/recording or the event trigger input from external device via Spectratech OEG-16-04 BNC cable for external signal input.
EXT-EVENT-IN 2:  It is used for the event trigger input from external device via Spectratech OEG-16-04 BNC cable for external signal input.
REMOTE: Cable from Spectratech OEG-16-05 Box for manual event trigger input is connected. The manual event trigger can be input from this Box besides the EVENT switch on the front face of the Main unit. The green LED on the Box lights when an event trigger was accepted.
USB: It is connected to PC with Spectratech OEG-16-06 USB cable for PC connection when various commands are given from the PC to Spectratech OEG-16 Main unit, or the PC receives the measurement data from the Main unit.
DC-IN:  Cable from the attached AC 110V adaptor is connected. It is used when operating by connecting with PC, or the battery operation is not required though it is an independent operation by Main unit.
GND: It is earth terminal. Please surely connect it to ground in the environment where it can ground.
BatteryUM3X4: For main part of Main unit
Please equip the battery set for a battery-powered operation of Spectratech OEG-16 Main unit. It consists of four AA batteries. It is capable of continuous operation for about 1 hour. When the capacity becomes insufficient, BATT LED on the front face of the Main unit lights (red) to warn about it. When the LED turned on, please exchange the battery set for a charged one in good time. When the LED turned on during measurement/recording, the recording is automatically ended, the data is saved, and it is put into halt state. In addition, it does not guarantee one hour in operation of this equipment with batteries other than the ENELOOP of SANYO. Please use the ENELOOP without fail.
BatteryUM3X2: For photo isolation part
The battery set is used when EXT-EVENT-IN 1 or EXT-EVENT-IN 2 of Spectratech OEG-16 Main unit is connected to external device. It consists of two AA batteries. Since the use of this battery makes a complete optical isolation between the external device and the Main unit, it can be connected to the external devices safely. It can be used continuously for about 6 months. When EXT-EVENT-IN1 or 2 is not used, this battery need not be equipped.

2) Spectratech OEG-16-01 Head module ——————————————————- 1 set

Head module

 It is the high-sensitivity part that is attached to the head to obtain biological information. It is composed of the optical components that are precisely made. Please handle it carefully.
The signal lines from each sensor part of the head module are concentrated into the two connectors. Please connect the connector of Cable L to SENSOR L, and do the one of Cable R to SENSOR R on the back face of the Main unit.

In addition, it is recommended to wipe off oil and dirt of the sensor part with rubbing alcohol before it is installed to the live body.

The example of wearing


3) Spectratech OEG-16-02 Phantom unit ——————————————————- 1 set

 This phantom unit is used to initially calibrate each light injection part and optical light-receiving part of the head module part. The initial calibration can be done only when it is connected with PC.


4) Spectratech OEG-16-03 Carrying bag ——————————————————– 1 set

Carrying bag Carrying bag

 This bag is an accessory to carry the Spectratech OEG-16 Main unit while performing the biometric measurement with it. It is possible to carry it on his/her back like a rucksack, by slinging it over his/her shoulder, or wrapping it around his/her waist.

5) Spectratech OEG-16-04 BNC cable for external signal input ——————— 2 sets
     (Cable 1.5m in length attached)

 The two BNC cables are used to start a measurement/recording by the Main unit or to input Event trigger from external devices. One end of the BNC cable is connected to EVENT-IN 1 or 2 on the back face of the Main unit, and the other one is connected to the output terminal of the external device with BNC connector, that can be used for the measurement/recording start or the Event trigger. The Main unit corresponds to the TTL output from external devices. When the output specification of the external instrument does not meet the TTL output, please inquire of our company or our agency once without forcibly connecting it.

  6) Spectratech OEG-16-05 Box for manual event trigger input ——————– 1 set
(Cable 3m in length attached)

Box for manual event trigger input

 It assumes to use this Box when it is required to perform an Event input manually a little distance away from the Main unit during the measurement/recording. Connector on the cable end of this BOX is connected to the REMOTE terminal on the back face of the Main unit. When the button of this Box is pushed during the measuring/recording, it is input as an Event trigger, and when it was acknowledged by the Main unit, the LED on the button turns on to indicate it.

7) Spectratech OEG-16-06 USB cable for PC connection ———————————- 1 pce

 When various commands are given to SpectratechOEG-16 Main unit from PC, or the PC obtains the measurement data from the Main unit, this cable is used to connect the Main unit with the PC.

8) Spectratech OEG-16-07 Install software in CD-ROM ————————————– 1 set

 Installing this CD-ROM software on PC makes it possible to use the application software for the Main unit. It can work on the PC with USB port, and Windows XP or Windows Vista installed.

9) AC adaptor for 110V (Domestic use) ————————————————————- 1 set

When SpectratechOEG-16 Main unit is not operated with the battery, the DC output cable of this adaptor is connected to DC-IN on the back face of the Main unit. Please refrain from use in other countries because this adaptor conforms to the domestic specification (Single phase AC 110V).

10) User manual (Software edition) ——————————————————————- 1 set

 It is the software manual on the PC to connect with the equipment. This user manual is also written in the CD-ROM of Spectratech OEG-16-07 Installation software in PDF format.

11) User manual (Technical edition) —————————————————————— 1 set

 This user manual is also written in the CD-ROM of Spectratech OEG-16-07 Installation software in PDF format.

Connection with external devices

For instance, Spectratech OEG-16 automatically received event beginning information and captures the event at the beginning point of speech stimulation of a speech stimulus presentation device. The following connection method is provided for such situation in which the event is input by pushing the switch (The accessory Box for manual event trigger input) at the point when the event that a measurer has wanted to mark occurred, and the measurement data is processed afterwards.

Connection with external devices

Example 1 of measurement

Word Fluency Test TASK that writes out the word which starts with “Se” .
(Measurement for about 1 minute, 53- years old woman)


TASK that writes out the word which starts with "Se"

Red: Variation of ΔOxyHb
Blue: Variation of ΔDeoxyHb
Yellow: It means start and end of TASK.
Initial value setting: At the point of starting measurement (About 30 seconds before starting TASK)
Filter characteristic: 0.3Hz LPF (Low pass filter)

CH1 Right hemispere, most outer neighborhood

CH2 (Point of failed measurement: Bad example)






CH8 Inner neighborhood

CH9 Inner neighborhood







CH16 Left hemispere, most outer neighborhood





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