Ultraviolet sensor
Contents
1. AQ TECHNOLOGY Ultraviolet sensor Product No 3277 Slow response ranges 1 0 500 mW m Resolution lt 0 4 mW m 2 0 5 W m Resolution lt 0 004 W m 3 0 50 W m Resolution lt 0 04 W m Fast response ranges 1 0 500 mW m Resolution lt 0 4 mW m 2 0 5 W m Resolution lt 0 004 W m 3 0 50 W m Resolution lt 0 04 W m Ry DATA HARVEST WO V Data Harvest Group Ltd 1 Eden Court Leighton Buzzard Beds LU7 4FY Tel 01525 373666 Fax 01525 851638 e mail sales data harvest co uk www data harvest co uk DS 064 Data Harvest Freely photocopiable for use within the purchasers establishment TECHNOLOGY Ultraviolet Sensor Contents OOHO Geos eehensiet date IEE E E oe neice ep eteeihe cities E E E AE 1 CONNEC UN erenn n E A E E E E AEE E EE E eee 1 FIO SS RE E AE TE OA E PEPE AAE SE A E E E E EAE E 2 BaCO OUNO e E E A stain tnaaiuasacmutans 2 AGC AN MOLVA OM ssassn RA REEERE EEEE 3 Mye SUJ OAS sere E E 4 Investigate absorption of UV radiation by suntan lotion a0annnnnaannnnnneannnnnnnnnnnonennnnennenenne 4 A a e E A E A 6 Introduction The Smart Q Ultraviolet sensor will measure the intensity of electromagnetic radiation in the ultraviolet UV A and B bands The Sensor uses a photodiode that is sensitive to UV in the range 215 nm to 365 nm 0 215 0 365 microns It has maximum spectral sensitivity at 300 nm Spectral response of the photodiode 0 122. identify markings made with a UV marker e g such as the 6V mini UV Fluorescent lantern with torch The one we purchased was supplied without a risk assessment check local regulations or the school advisory service e g SSERC CLEAPSS for guidance e The output from an ultraviolet lamp is normally made visible by emitting some violet light true ultraviolet is invisible e Fluorescent lamps produce UV light by the emission of low pressure mercury gas Fluorescence occurs when UV is absorbed by a phosphorescent coating on the inside of the tube and re emitted as visible light e The sun is a source of UV UV in sunlight can in some cases penetrate clouds mist and fog Fresh snow can reflect up to 85 of the sun s rays e Halogen bulbs or lamps that are not UV protected by a plastic or glass shield are another source of UV Investigations Using the Slow range e Absorption of ultraviolet by different types of clothing not related to colour e Whether the colour of clothing affects absorption of UV e Investigate the UV protection provided by sunglasses e Investigate absorption of UV radiation by suntan lotion e Investigate how different material like plastic glass auto glass comparison clothes soft drinks etc absorb or reflect UV light e Direct or diffuse solar radiation a considerable amount of UV does not come directly from the sun but is scattered by the atmosphere e Fluorescent rocks e Fluorescent dyes from w
3. socket on the data logger e The logger will detect that the Ultraviolet sensor is connected and display values using the currently selected range If the range is not suitable for your investigation set to the correct range TECHNOLOGY Ultraviolet Sensor Ranges With some EasySense loggers it is possible to set the range from the logger Please refer to the logger s user manual To alter the range in the EasySense software 1 2 3 5 Or i 2 3 4 Select EasyLog from the Home screen Select the New recording wizard icon f Real Time Logging Wizard xs New Click on the sensor s name it will be listed r gt UV 50W n S using its current range Sensor 2 No Sensor Sensor 3 No Sensor A set sensor range window will open Select Sensor 4 No Sensor the required range then OK Select Finish to exit the wizard From the Home screen select Sensor Config from the Settings menu select the Ultraviolet sensor from the list and click on the Change Range button The current range will be highlighted Select the required range and click on OK Close Sensor Config The range setting will be retained until changed by the user Background Electromagnetic radiation is a transfer of energy through space via waves of oscillating electromagnetic fields What distinguishes the parts of the electromagnetic spectrum is the frequency of the oscillation and
4. to be free from defects in materials and workmanship for a period of 12 months from the date of purchase provided they have been used in accordance with any instructions under normal laboratory conditions This warranty does not apply if the Sensor has been damaged by accident or misuse In the event of a fault developing within the 12 month period the Sensor must be returned to Data Harvest for repair or replacement at no expense to the user other than postal charges Note Data Harvest products are designed for educational use and are not intended for use in industrial medical or commercial applications WEEE Waste Electrical and Electronic Equipment Legislation Data Harvest Group Ltd is fully compliant with WEEE legislation and is pleased to provide a disposal service for any of our products when their life expires Simply return them to us clearly identified as life expired and we will dispose of them for you
5. 0 10 0 08 0 06 0 04 0 02 Linear Spectral Response S A W 200 225 250 275 300 325 350 375 400 Wavelength nm The unit for ultraviolet irradiance is W m Measurements can be recorded at three levels using either a Slow or Fast response range e The slow response ranges are 0 500 mW m 0 5 W m and 0 50 W m e The fast response ranges are 0 500 mW m 0 5 W m and 0 50 W m The slow response is the most commonly used range and Is suitable for use in most ultraviolet investigations The response has been smoothed to remove rapid fluctuations of UV If a slow range is selected it will be indicated by an S after the range on the sensor axis e g UV 5W m S W m The fast range is used to show mains frequency ultraviolet fluctuations These variations in UV intensity can be a source of interference for general work If a fast range is selected it will be indicated by an F after the range on the sensor axis e g UV 5W m F W m The Smart Q Ultraviolet sensor is equipped with a microcontroller that greatly improves its accuracy precision and consistency The microcontroller contains the calibration for the six ranges The stored calibration for the selected range is automatically loaded when the Ultraviolet sensor is connected Connecting e Push one end of the sensor cable Supplied with the EasySense logger into the shaped socket on the Ultraviolet sensor Connect the other end of the sensor cable to the input
6. adily 99 of the ultraviolet that reaches the Earth s surface is UV UV A band A In general this is the least harmful band of UV but near UV 315 400 nm with high exposure can cause reddening of the skin Sunburn UV A rays are longer and able to penetrate Tanning rays the skin more deeply More responsible for premature ageing and wrinkling of the skin Increasingly being linked to eye damage and the formation of skin cancer The cancer inducing properties of UV are proportional to its ability to damage cell DNA The longer you are exposed to UV the more likely that damage will take place Sunburn is not connected with the sensation of heat When we are exposed to strong sunlight passing through glass in a window that absorbs UV B despite the sensation of heat our skin does not burn When exposed to sunlight in cold weather at high altitudes our skin can burn despite feeling cold The Smart Q Ultraviolet Sensor measures UV light intensity as irradiance in W m There are other ways that UV intensity and exposure are measured E g 1 The Ultraviolet Index UVI which is a measure of the solar ultraviolet UV intensity at the Earth s surface relevant to the effect on human skin The higher the UV index number the greater the penetrating power of the UV radiation and the more likely the damage to skin 2 The Effective UV Dose is directly related to the onset of sunburn and is an integral of the Effective UV Intensity
7. ashing powders that absorb UV and then emit light e Different light levels produce different UV levels Using the Fast range e Variation of UV along a fluorescent tube compared to light output Investigate absorption of UV radiation by suntan lotion The sun protection factor SPF was developed to rate the general effectiveness of sunscreens and lotions to block UV B rays Historically UV A was not seen as damaging and the ability to block this section of the UV spectrum was not included For this activity you would need a UV source We used a small battery powered UV fluorescent lantern supplied as a security device for identifying markings made with a UV marker e Arrange the UV source so it shines at the Ultraviolet sensor at a distance of about 100 mm Use a blob of plasticine to secure the Sensor in place e Turn onthe UV lamp about 5 minutes before the investigation starts to allow the tube to warm up and stabilise TECHNOLOGY Ultraviolet Sensor 100 mm lt Glass or plastic slide i Saal o S Ultraviolet sensor Plasticine or Blu Tack to hold the test slide Ultraviolet lamp Suntan lotions of varying SPF s use the same carrier types e g oil cream or milk e Make up a microscope slide for each SPF value of suntan lotion Label the slide with the name and SPF value Either smear a drop of the lotion over the surface of the slide or use second slide to drag the lotion across You need
8. consequently the wavelength The Ultraviolet UV radiation band in the electromagnetic spectrum extends from the very short wavelengths of 100 nm to 400 nm which is just above violet light in the visible region of the spectrum Latin word for beyond is ultra True ultraviolet light is invisible Visible Light Region Violet 400 450nm Blue 450 500nm Green 500 570nm Yellow 570 590nm Ultraviolet Radiation Region Orange 590 610nm Red 610 700nm Nm 100 200 300 400 500 600 700 The Ultraviolet spectrum is divided into four smaller bands according to the nature of the radiation UV A is closest in wavelength to visible light Vacuum or UV C are closer to the soft X ray region of the electromagnetic spectrum Vacuum UV The energy in this band can only be transmitted in EA Ultraviolet Sensor UV C radiation from the sun would be harmful but it is UV C band 200 280 nm completely absorbed by the ozone in the Earth s upper atmosphere and does not reach the surface UV B radiation from the sun is partly absorbed in the UV B band Earth s atmosphere mainly by ozone Also called actinic radiation since the high photon energy of the Actinic 280 315 nm radiation induces chemical processes including radiation changes in biological systems photo biological Burning rays systems which can induce cancer This band is the primary danger to humans UV A penetrates the Earth s atmosphere re
9. over the exposure time The dose unit is called MED or Minimal Erythemal Dose minimum erythemal dosage units per hour Both the UVI and the MED hour units take into account the erythemal response curve for reddening of skin The response curve follows the varying sensitivity of the average person to different wavelengths Skin sensitivity decreases rapidly over the UV B range approximately 100 times less sensitive every 20 nm and decreases less rapidly over the UV A range approximately half as sensitive every 20 nm The Ultraviolet sensor does not have wavelength weighting corresponding to the erythemal action spectrum so the readings cannot be converted to the UVI or MED hour units Practical information e Ordinary glass can cut off some UV that has a wavelength less than 300 nm e An appropriate UV light source would be within the UV A band because it s the least hazardous UV radiation to work with A risk assessment should be made on the type of UV light source used Refer to local regulations or the school advisory service e g SSERC CLEAPSS for guidance e Use a screen around a UV lamp so that pupils are not exposed to its direct rays SEA Ultraviolet Sensor e Even with UV A care should be taken to reduce exposure to the source to as little time as possible e Wemade use of a small hand held battery powered ultraviolet light source which emits mainly UV A radiation These are supplied commercially as security devices to
10. to make sure the slide is coated evenly Liaise 2 Push back 1 Push forward lt e Place another blob of plasticine about 20 mm in front of the Sensor to hold the test slide e Connect the Ultraviolet sensor to the data logger e Open the EasySense program and select SnapShot from the Home page If the Y Axis doesn t show a slow response range e g 5 W m S change to a slow range e Select Test Mode from the Tools menu and check that the reading from the Ultraviolet sensor is within range If not change to a more suitable range see page 2 e Click on Start to begin recording e Position an untreated slide in front of the Sensor and click in the graph area to record the UV value for plain glass transmission e Swap the plain glass slide for a lotion coated slide Click on the graph area to record the UV value for this value SPF e Repeat until all slides have been tested and click on Stop e Use Add Text to identify each bar e g Plain glass SPF value SEA Ultraviolet Sensor The investigation could be extended 1 To test home made lotions e g olive oil bay oil etc to see if they have any effect 2 The slides could be swished around in water to simulate swimming and retested 3 The slides could be retested after several hours to see if the effectiveness of the lotion decays with time 4 Does the lotion loose effectiveness if kept for a year Warranty All Data Harvest Sensors are warranted
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