ERYTHEMA and MELANIN 210 series User manual April 1996

Erythema Meter 210 Series

User Manual

Copyright © Dia-Stron Limited 1997 Neither the whole nor any part of the information contained in, or the product described in this guide, may be adapted or reproduced in any material form except with the prior written approval of Dia-Stron Limited. 2nd Edition April 1997 Published by: Dia-Stron Limited Unit 9 Focus 303 Business Centre Andover Hampshire SP10 5NY United Kingdom Telephone: +44 (0)1264 33 47 00 Facsimile: +44 (0)1264 33 46 86 E-Mail: [email protected] Dia-Stron Limited 1st Floor 390 Reed Road Broomall PA 19008 USA Telephone: 610 328-9038 Facsimile: 610 544-6305 E-Mail:

Trademarks and Tradenames used in this guide are acknowledged to be the Trademarks and Tradenames of their respective Companies and Corporations.

__________________________________________________________________________________ 2

Erythema Meter 210 Series

User Manual

EC DECLARATION OF CONFORMITY REF: EMC DIRECTIVE 89/336EEC LOW VOLTAGE DIRECTIVE 93/68/EEC We:

Dia-Stron Ltd., Unit 9, Focus 303 Business Centre South Way Andover Hants SP10 5NY Tel: +44 1264 334700

Declare in sole responsibility that the Equipment: Erythema Meter Model 210 Conforms with the protection requirements of the above directives and complies with the following generic standards: EMC Emissions EMC Immunity

EN50081-1 EN50082-1

The Equipment is designed in accordance with safety standard: IEC 1010-1: Equipment for Measurement, Control and Laboratory Use. Copies of the Technical Documentation File are available on request from Dia-Stron Ltd. Name: S.P.Bucknell Date: 01.04.96

Signature of Authorised Representative: (Technical Director)

__________________________________________________________________________________ 3

Erythema Meter 210 Series

User Manual

SECTION 1: FOR FIRST TIME USERS A BRIEF DESCRIPTION The Erythema Meter measures the amounts of the two principle skin chromophores, haemoglobin and melanin, present in the skin. The ERYTHEMA INDEX is based on the work of DIFFEY and FARR (Ref. British Journal of Dermatology (1984) III, p663-672). In brief, the Erythema Meter contains at tungsten-halogen lamp shining white light into a fibre optic probe. The probe illuminates the skin and then collects diffuse light scattered from within the skin. The light is analysed within the instrument by narrow band interference filters at three wavelengths: i) 546nm (green) ii) 632nm (orange/red) iii) 905nm (near infra-red) The 546nm filter coincides with a peak in the haemaglobin absorption spectrum. The strength of this signal is inversely proportional to the amount of haemaglobin present. By taking the ratio of the 546nm result with a reference signal (632nm) to compensate for skin tone and probe alignment an ERYTHEMA INDEX can be calculated. The displayed ERYTHEMA INDEX is: = log10 (632nm/546nm) * 1000 The instrument has a dynamic range of +999 to -99 erythema units. In the case of pigmentation, the 632nm filter is sensitive to the amount of melanin present and the 905nm filter is used as a reference signal. The displayed MELANIN INDEX is: = log10 (905nm/632nm) * 1000 The instrument has a dynamic range of +999 to -99 melanin units.

__________________________________________________________________________________ 4

Erythema Meter 210 Series

User Manual

ADDITIONAL REQUIREMENTS The Erythema Meter is ready to use as supplied. It is useful to record the results using a printer or personal computer (PC). Section 5 gives a recommended printer and instructions for interfacing a printer to the Erythema Meter. Section 6 gives similar information for PCs.

__________________________________________________________________________________ 5

Erythema Meter 210 Series

User Manual

SECTION 2: GETTING STARTED ERYTHEMA METER COMPONENTS Check that you have received all the items on the packing list. The front panel has 3 features: 1. An LCD display to show erythema/melanin indices and operating information. 2. A four-key membrane switch pad for operating the instrument. 3. A receptacle for holding the light wand. The base of the holder is made from a white reference material for use as a zero baseline. 4. Screen contrast control. The rear panel has 6 features: 1. The mains inlet socket. The mains voltage has been pre-set but can be changed by removing the fuse-holder at the base of the mains inlet. The white arrow next to the required line voltage should be set POINT DOWN. 2. Ventilation grill. The Erythema Meter uses a tungsten-halogen source which generates heat. To ensure stable operation, the ventilation grill should not be covered. Similarly, ventilation slots on the base of the instrument should be free from obstruction. 3. A 3-pin socket for connecting the footpedal accessory. 4. A 9 pin D-type socket for connecting the Erythema Meter to a PC. 5. A 9-pin D-type plug for connecting the Erythema Meter to a serial printer. 6. An access port to internal instrument controls (label GAIN).

__________________________________________________________________________________ 6

Erythema Meter 210 Series

User Manual

CONNECTING UP To operate the Erythema Meter, connect the footpedal accessory to the appropriate socket on the rear panel. Place the probe in the front panel holder. Connect mains lead. If required, connect a printer or PC as described in Sections 5 and 6.

SWITCH ON - THE BASIC SCREEN Switch on. After a short delay an audio alarm indicates the instrument is ready to use. An ERYTHEMA INDEX then displayed on the right side of the screen. Four boxes appear along the bottom of the screen and these set the functions of keys 1 to 4. The box on the extreme right shows the letters ERI, the initials meaning ERythema Index. The box is displayed in bold to show that this feature is currently in use. The MELANIN INDEX is activated by pressing key 2 corresponding to the Melanin Index box. This is normally switched off at start up. The remaining boxes are not in bold indicating these functions are not selected.

__________________________________________________________________________________ 7

Erythema Meter 210 Series

User Manual

SECTION 3: MAKING MEASUREMENTS Remove the probe from its holder. As the probe is moved around or placed on different skin sites, the ERYTHEMA INDEX changes. When the probe is not in contact with a surface, it is normal to see a reading of -99 units as no light is being reflected into the probe. When making measurements, place the probe LIGHTLY on the target area for a couple of seconds. Do not apply excessive pressure as this may cause blanching. Try to keep the probe perpendicular to the skin. Changing the probe angle or pressure may lead to slight changes in index. To record the current reading on a printer or PC, press the footpedal once. The Erythema Meter is currently operating in FREE mode, the readings constantly changing as the probe is moved. A useful feature is MEAN mode. In MEAN mode, the instrument averages 100 fast samples and puts the mean result on the screen. The display then remains static until another measurement is started by either pressing any key briefly or the footpedal. Refer to the next section for details on MEAN mode.

__________________________________________________________________________________ 8

Erythema Meter 210 Series

User Manual

SECTION 4: USING THE ERYTHEMA METER 'PAGE' BOX

KEY 1

Press this key to select a second screen showing alternative functions. Note that the use of each key is now re-defined. The new functions available are: Exit Mean Data Refer to the descriptions of each. 'MNI' BOX

KEY 2

Press this key to switch the MELANIN INDEX on/off. When the index is on, the box is shown in bold. The MELANIN INDEX is displayed on the lefthand side of the screen. The MELANIN INDEX will not switch off if the ERYTHEMA INDEX is also off. The instrument requires at least one indice to be displayed at all times. If your instrument has not been fitted with the Melanin Index filter the MNI box will not appear. 'ZERO' BOX

KEY 3

The 'ZERO' switch is used to autozero the instrument. This is an automatic procedure requiring no user adjustments. Before starting autozero, ensure that the probe is placed in the probe holder. Press the 'ZERO' switch. A message will be displayed requesting the user to press any key to start autozero or the footpedal to cancel autozero. When the autozero is complete (this takes around 3 seconds) an alarm sounds and the standard screen appears. Measurements can now be resumed. The reading from the probe holder should now be zero. It is recommended to autozero the instrument each time it is switched on. The autozero should be repeated after 15 minutes to correct for any drift during the warm-up period. Note: autozeroing against other surfaces may result in false erythema indices.

__________________________________________________________________________________ 9

Erythema Meter 210 Series

'ERI' BOX

User Manual

KEY 4

Press this key to switch the ERYTHEMA INDEX on/off. When the index is on, the box is shown in bold. The ERYTHEMA INDEX is displayed on the righthand side of the screen. The ERYTHEMA INDEX will not switch off if the MELANIN INDEX is also off. The instrument requires at least one indice to be displayed at all times. If your instrument has not been fitted with the Erythema Index filter the ERI box will not appear. 'EXIT' BOX

KEY 1

Press this key to return to the standard screen. 'MEAN' BOX

KEY 2

Select this key to put the instrument into MEAN (data averaging) mode. When this feature is in use, the MEAN box is shown in bold. After selecting averaging mode, use the EXIT key to return to the standard screen. The erythema display is no longer active in that it is not being constantly updated. To make a measurement, press the footpedal once. The instrument will now average the data being collected for a period of 3 seconds. An alarm will sound when the data is collected and it is OK to move the probe. The mean ERYTHEMA INDEX is then displayed on the screen. The displayed index is an average of 100 seperate erythema readings. Press the footpedal again to make another measurement. At the end of each measurement cycle, the instrument will automatically send a report via the printer and PC ports. If these are not required, ensure that the printer or PC is off-line or disconnected. To end MEAN mode, press the PAGE key and then the MEAN key. The MEAN box will now be switched from bold to normal display showing that the feature is not in use.

__________________________________________________________________________________ 10

Erythema Meter 210 Series

'DATA' BOX

User Manual

KEY 3

Select this key to monitor the 'raw' data being collected by the .instrument. The absolute reflectivities are shown for the 546nm, 632nm and 905nm channels in a range of 0-4095 units. The higher the reading, the greater the amount of reflected light detected. This mode is useful for checking the correct operation of the instrument and as part of the lamp replacement procedure.

__________________________________________________________________________________ 11

Erythema Meter 210 Series

User Manual

SECTION 5: COLLECTING DATA WITH A PRINTER A RECOMMENDED PRINTER Dia-Stron Ltd. recommend the use of Hewlett Packard 2225D (Thinkjet) serial printer with the Erythema Meter. If this model is used, then the printer bit switches should be set as follows: Mode dn up dn up up up up dn 1

2

3

4

5

6

7 8

RS-232 up dn dn dn dn 1

2

3

4

5

Alternatively , an IBM PC compatible printer with a serial interface should be suitable. PRINTER INTERFACING The Erythema Meter can drive serial IBM PC compatible printers. The 9-pin D-type printer plug is a standard IBM AT type RS-232 port. Dia-Stron Ltd. can supply a suitable cable for connection to most serial printers. Standard data transmission is at 9600 baud, 8 data bits, no parity, 1 stop bit. Alternative baud rates can be set by changing internal link settings. Please contact Dia-Stron Ltd. for advice if required.

__________________________________________________________________________________ 12

Erythema Meter 210 Series

User Manual

AN EXAMPLE PRINTOUT An example printout produced by the Erythema meter is shown below: Patient name: Date: Time: Erythema Index = 469 Melanin Index = -17 Reflectivity ( 632nm ) = 1287 Reflectivity ( 546nm ) = 437 Reflectivity ( 905nm ) = 1338 The headings Patient name, date and time are left blank for the user to complete. The ERYTHEMA and MELANIN indices are then given alongwith the 'raw' data used to calculate them.

__________________________________________________________________________________ 13

Erythema Meter 210 Series

User Manual

SECTION 6 : COLLECTING DATA WITH A PC PC INTERFACING The PC interface is a 9 pin D-type socket conforming to the IBM-AT pin specification. Dia-Stron Ltd. can supply suitable cable for connection to all PCs. Data transmission is at 9600 baud, 8 data bits, no parity, 1 stop bit. PIN

RS232 NAME

DIRECTION

DESCRP.

1 2 3 4 5

DCD RxD TxD DTR SG

IN IN OUT OUT -

DATA CARRY DETECTED DATA IN DATA OUT EXTERNAL DEVICE READY SIGNAL GROUND

Pin definitions as seen by Erythema Meter. DATA OUTPUT FORMAT The data string output to a PC consists of a string of ASCII characters as follows: <632nm data> <space> <546nm data> <space> <905nm data> <erythema index> <melanin index> <carriage return> <line feed>

__________________________________________________________________________________ 14

Erythema Meter 210 Series

User Manual

SECTION 7: USEFUL INFORMATION ROUTINE SERVICE No routine maintenance is required. Regular autozero checks are recommended to guard against long-term drift associated with the ageing of the tungsten-halogen source. The probe tip may be cleaned with a light detergent solution. Ensure that the aperture is completely dry before re-use. The fibre optic cable within the probe tip aperture may be wiped with cotton wool dipped in alcohol. Do not use abrasive materials on the fibre optic cable. The zero reference material within the probe holder can also be cleaned with alcohol should this be necessary.

__________________________________________________________________________________ 15

Erythema Meter 210 Series

User Manual

REPLACING THE LAMP If the source lamp fails please advise Dia-Stron Ltd. The lamp should be replaced by a authorised service agent. The lamp can be replaced by the user as follows: 1. Disconnect the instrument from the mains supply. 2. Remove top pair of rear panel screws and all screws from base. 3. Slide instrument cover forward and then to one side. Lay instrument cover in such a way as to avoid strain on connecting cables. 4. Remove metal heat shield cover which lies along centre of instrument. 5. Lift heat shield clear taking care to avoid fibre optic cables. 6. Remove old lamp by applying uniform pressure upwards. 7. Insert new lamp. 8. Reassemble instrument by following steps 1-6 in reverse order. 9. Switch on and allow to stabilise for 15 minutes. 10. Select 'DATA' function. 11. Place probe in holder. 12. Readings for all channels should be equal and in the range 3200-3700. 13. If not, remove blanking grommet from rear panel GAIN aperture. 14. Adjust the exposed controls until conditions in (12) are met. Righthand adjustment - 632nm Centre adjustment - 546nm Lefthand adjustment - 905nm 15. Replace blanking grommet. 16. In case of repetitive lamp failure, please contact Dia-Stron Ltd.

__________________________________________________________________________________ 16

Erythema Meter 210 Series

User Manual

WARRANTY AND FAULT REPORTING If a fault is suspected, please contact Dia-Stron Ltd., Dia-Stron Ltd. Unit 9 Focus 303 Business Centre South Way Andover, Hants. SP10 5NY. Telephone: 01264 334700 Fax: 01264 334686 E Mail: diastron @compuserve.com Warranty: This instrument and its accessory components are guaranteed against failure and faulty workmanship for a period of 1 year from the delivery date. Full details are given in the Dia-Stron standard terms and conditions (available on request).

__________________________________________________________________________________ 17

Erythema Meter 210 Series

User Manual

SECTION 8: APPENDICES FUSE INFORMATION The Erythema Meter has four fuses, two internal, two external. The internal fuses should only be replaced by authorised personnel. The external fuses are rated as follows: UK, EUROPE USA, JAPAN

T1.0 Amp, 250 Volt T2.0 Amp, 250 Volt

To replace external fuses, follow procedure below: 1. Disconnect instrument from mains supply. 2. Remove fuse holder from base of mains inlet by inserting small screwdriver into fuse holder cover. 3. Replace both fuses with the correctly rated fuse. 4. Replace fuse holder in mains inlet. Make sure the correct line voltage is selected. (The white arrow next to the required line voltage should be aligned POINT DOWN). 5. Reconnect mains supply and test instrument. 6. For repetitive fuse failure, disconnect from mains supply and contact Dia-Stron Ltd.

__________________________________________________________________________________ 18

Erythema Meter 210 Series

User Manual

TECHNICAL SPECIFICATION Warm up period

:30 minutes

Index range Index resolution Index non-linearity

: -99 to +999 :1 : <1%

Signal bandwidth ADC

:20Hz :12 bit

Filter FWHM

:10nm

Power consumption Voltage (selectable) Frequency

:60W :220/115V :50/60Hz

External fuses (220v mode) (115v mode)

:T1.0 250v :T2.0 250v

All fuses 20mm Slo-blow. Computer port Printer port

: 9 pin DTE format : 9 pin DTE format

Printer baud rates configured by internal link settings.

__________________________________________________________________________________ 19