Laser Roughness Tester TRL400 Instruction Manual

Transcription

1 CONTENTS 1 Chapter One General 1 2 Chapter Two The technical parameters and performance features of the instrument 4 3 Chapter Three How to use the instrument 6 4 Chapter Four Fitting software -Calibration 36 5 Chapter Five Maintenance and Repairing 45 6 Appendix Laser Roughness Tester TRL400 Instruction Manual 56

2 1 Chapter One General 1.1 Principle of measurement TRL400 laser roughness tester is the latest product developed by Wenzhou Graigar Instruments Ltd. This product is suitable for rapid and non-contacting roughness measurement to the processed surfaces. Place the measurement transducer on the measured surface, the laser inside the measurement transducer will give off a bunch of pulse light; the light will illuminate the measured surface, and the detector inside the transducer will receive the reflecting light intensity as well as the scattering light intensity from all the directions after the reflecting and scattering on the surface. The current-voltage conversion circuit in the measuring transducer will convert the current signal detected by the detector to the voltage signal, and it will amplify the signals via the operational amplifier. The amplified signals will be input in the controller via the cable between the controller and the transducer. The A/D conversion circuit in the controller will perform the A/D conversion to the signals then input them to the digital signal processing for handling, then the roughness feature value of Ra of the measured surface will be displayed on LCD screen. 1 Laser Linear sensor Specular reflection Reflector Scattering Figure 1.1 The principle of measurement of laser roughness tester 1.2 The standard delivery Item Quantity TRL400 transducer 1 TRL400 Main unit 1 Power adaptor 1 Protective leather sheath 1 Communication cable 1 Table 1-1 Standard delivery for TRL400 2

3 1.3 Measurement procedure Laser Roughness Tester TRL400 is the comparative measuring instrument, that is, TRL 400 will measure the roughness feature value of the sample plate, then it will establishes a verification curve according to the roughness of the known sample block. By such way the roughness value of the surface of the measured piece can be obtained. When measuring the roughness with TRL 400, the user should follow the several following steps: 1. Firstly, obtain a group of roughness values of the standard sample plate (please note that usually the user should get a group of values with different roughness values). 2. Use the mode establishment function of TRL 400 to measure the roughness feature value of the standard sample blocks, then upload them to the Calibration software in the PC (even for the sample blocks with the same roughness value, they might have different measured feature values because of different processing methods). 3. Select the suitable fitted curve to analog the model parameters, then download them to TRL Select the simulated model parameters as the default model, then enter the measurement menu for the measurement. 3 2 Chapter Two The technical parameters and performance features 2.1 Measurement range and errors 1) Measurement range: 10nm Ra 1.0 m; 2) Measuring repeatability: ±3% 2.2 Operating environment Working temperature: 0 ~ 40 Working humidity: 20% 75%RH Storage temperature: -25 ~50 Storage humidity: 20%~90% RH 2.3 Power The instrument should not be exposed to magnetic field, dust and corrosive atmosphere. Lithium battery 4 3.6V 2200mAh Adaptor: Input 100~240V 50HZ~60HZ Output 9V 2.5A 4

4 2.4 Dimensions and weight Dimensions: about 164mm 100 mm 46 mm Weight: about 1.1kg 2.5 Performance features 1. Rapid and non-contacting measurement, which is suitable for test the Ra value (the roughness of the working pieces) or the quality control of the working pieces. 2. The high sensitive photo-sensor is set inside the transducer TFT_LCD screen, the resolution is 320* The DSP chip is used for the data processing, it is rapid and has low power consumption. 5. There are lithium battery of large capacity and the charging controlling circuit inside; they have no memory effect; there is the over charging or releasing protection. The battery can work for long time continually. 6. The standard RS232 interface inside, it can communicate with PC, upload the data or download the model parameters, etc. 7. Shut-down automatically, memorize and provide various kinds indicating information sets of models and 88 sets of measurement data can be stored. 5 3 Chapter Three How to use the instrument Figure Instrument outlook 6

5 3.1 General description of the instrument Name of the various parts of the instrument Functional keyboard The TRL400 keyboard is divided into three groups: function selection, menu selection and number key functions. Function selection: it includes six keys, one key for power on and shut-down, and five other keys for sending, storage, model establishment, deletion and measurement. Menu selection: it includes six keys, four direction keys (up, down, left and right), enter key and exit key. These keys can realize the menu selection, browsing, exit and other functions. Keys of number functions: it is mainly used for inputting the mode parameters. For the total keyboard layout, please refer to the following figure. 7 Figure Keyboard panel Using of the power TRL400 can use the plug-in power device (AC DC adaptor) or battery for the operation. When the power adaptor is used as the working power of TRL 400, the user should plug in the power adaptor, then the instrument will examine automatically and switch to the power of adaptor, it will 8

6 also charge internally. After taking off the power adaptor, the instrument will examine automatically and switch to the internal power. If the battery voltage is too low and is displaying on the left upper corner of the screen (as the electric quantity indicator), the user should switch to the power adaptor as soon as possible, such can ensure the successful measurement and the battery charging. Insert the plug of power adaptor to the power socket of the instrument, then connect the power adaptor to the voltage of 220V 50HZ, then the red light of the charging indicating light lights on, the charging begins. At the same time, the indicating symbol for electric quantity will be displayed at the left upper corner of the screen. When the standard delivery power adapter is used; the internal lithium battery should be charged for 4 6 hours continually. When the red light of charging LED lights out and the green light lights up, the lithium ion battery has been totally charged. Note: Please pay attention to the symbol of power supervision at the left upper corner of the screen, there are three status: the battery has been totally charged; 9 indicates the current electric quantity of the battery, the red vertical strips indicates the percentage of the remaining electric amount of the battery; the battery voltage is too low, please charge as soon as possible; When charging, TRL 400 can be switched on or off in any status Switch on and shut-down of the instrument a) Prepare the working pieces to be measured. b) Insert the plug of the transducer cable into the socket above main unit and rotate the plug tightly. c) Press key to switch on the instrument. d) The program loaded and performed self-examination. Under the normal condition, the tester will enter the main menu automatically. The system will select the function of Measurement by default. e) Check the voltage of the battery. f) Place the transducer on the workpiece to be measured, load the menu of the main unit to perform the measurement. 10

7 g) After the operation completes, press key to shut down. Note: TRL 400 has the function of automatic shut down, if the user doesn t press any key within 10 minutes, the instrument will give a beep to alarm the operator. After that, if there is still no button pressed within one minute, the machine will be shut down automatically. 3.2 Brief introduction to the instrument operation Announcements before operation The surface to be measured: the surfaces of the working pieces should have no greasy dirt or other dirt, it should be cleaned by the gasoline or alcohol. The position to be measured: make the sharp angle of the red icon at the side surface of the transducer point to the position to be measured, then place the transducer on the surface to be measured smoothly and reliably. The transducer direction: the transducer direction should be perpendicular to the direction of the texture of the processed surface of working pieces to be measured Switch on the machine Press key to switch on TRL 400, after a beep, the launching interface as figure will display, which prompts the user that TRL 400 is performing and self-examining. Figure The interface of self-examination after switch on This procedure will last for 7 seconds, if the key board don t react during this procedure, the main menu will show after the initializing, please refer to Figure

8 Figure The interface of main menu The interface indicates that TRL 400 can work normally Measurement menu Press the direction key and make measure red, then press key menu, please refer to Figure to enter measure 13 Figure Measurement menu Current value Ra: Press key to perform one measurement to the surface roughness, the measurement values will be written to the current value Ra. Average value Ra: the arithmetic average value of many measurement values (maximum 20 values). Total number of the measurement data: Count for the operation of the surface roughness measurement, it can record 20 times at most; when at the 20th number, the user should press 14

9 key again for measurement. Press or can clear the total number of the measurement data. Store the total number of the stored data: store the current results of measurement, press key to store the average value to the local space, and the total number of the stored data will add 1 automatically. After the measurement completes, press key to return to the main menu Comparison menu The comparison operation is a kind of simplified measurement of the surface roughness, users doesn t need to know the concrete roughness value of the surface, for he can only determine the quality of the working pieces according to the percentage of the roughness feature value of the surface of working pieces to be measured in the difference of that of the standard surface. It is mainly used in the quality control. The concrete procedure: first measure the roughness feature values of the surface of standard workpiece, then this measured feature value is stored in TRL400 as threshold. Then measure 15 the roughness surface to be measured, and compare that value with the threshold. The percentage between the difference and the threshold will be displayed at the right side of the interface, which will be used by the instrument operator to determine the quality of the surface to be measured. Press the direction key to make Comparison red, then press key to enter the Comparison menu, please refer to the figure Figure Comparison menu 16

10 Current value: press key to measure the feature values of the surface roughness, and the feature values will be written in the current values. At the same time, the percentage between the difference and the threshold will be displayed. If the percentage exceeds 99%,!!% will be displayed. Please refer to the figure Average value: The arithmetic average value of the roughness feature values of the measured in many times. At most 20 times of measurement can be performed. At the same time, the percentage between the difference and the threshold will be displayed. If the percentage exceeds 99%,!!% will be displayed. Total number of the measurement data: Count for the operation of the feature values of the surface roughness, it can record for 20 times at most; when at the 20th number, the user should press key again for measurement and the total number will become 01. Press or can clear the total number of the measurement data. Threshold: press key or key, and the average value will be stored in the 17 threshold storage space as the surface feature values. Press key and clear the threshold. After the measurement completes, press key to return to the main menu. Figure Display of the percentage between the difference and threshold Model menu Press the direction key to make Model red, then press key to enter the Model menu, please refer to the figure

11 Figure Model menu There are three sub-menus under Model menu: Select sub-menu: it means the selection of the default model, the default model includes the parameter values needed for the normal working of the instruments. Setup sub-menu: it means the creation, altering and other operations to the selected models. Delete sub-menu: it means the deletion operation to the selected model. Press the direction key to switch among the three sub-menus. 19 Press key to return to the main menu Submenu Select in the Model menu Press the direction key to make Select turn red, then press key to enter the Model menu, please refer to the figure TRL 400 instrument regulates that, the model index number 01 is the default model, and the model with the index number from 02 to 64 can transfer the parameters to the default model via the Select operation. TRL 400 will calculate the feature values according to the model parameters and obtain Ra value the surface roughness. Press or key to browse the model parameters in a circular way. Press key to transfer the model being currently browsed to the default model. Press key to return to Model key. 20

12 Figure The default model selection Submenu Setup in the Model menu Press the direction key to make Setup turn red, then press refer to the figure key to enter the Model menu, please 21 Figure Setup menu There are two sub-menus under Setup menu: Input sub-menu: realize the establishment of new models and the manual altering, online downloading and other functions to the existing model parameters. Calibrate sub-menu: realize the feature value measurement, storage, upload, download and other functions to the newly established models and sample blocks. Press the direction key to switch between the two sub-menus. 22

13 Press key to return to main menu Input in the Setup sub-menu Press the direction key to make Input red, then press refer to the figure key to enter the Input menu, please Figure Input menu 23 In the non-altering status: Press or key and browse the model parameters in a circular way so as to determine the index number of the model to be altered. Press or or key and enter the altering status, then, the altering cursor will occur below unit: m. Press key to add new model, all the default parameters of the model are zero, and the establishment time is the current time. In the altering status: Press or key and the altering cursor will indicate in the parameter projects included in the model in a circular way. Press or key and select in three options: unit, process and material. They will be invalid in other projects. And the altering project includes the following options: Unit: micrometer Process method: other, milling, turning, grinding, polishing, external grinding, scraping, manual scraping, burnishing, plain milling, end milling, internal hole grinding, truning, internal hole boring, electric park, digging. Material: Other, iron, steel, aluminum, alloy, nickel alloy, titanium, copper, glass and plastic. For other items, please press digit keys and input the parameters. 24

14 Press or key to save the altered parameters. Press key to return to main menu Calibrate in the Setup sub-menu Press the direction key to make Model establishment in the Model establishment menu red, then enter the key to enter the Model establishment menu, please refer to the figure Figure Model establishment menu 25 Press or key to select the index number of the model to be altered. Press key to add new model, all the default parameters of the model are zero, and the establishment time is the current time. Press key measure the roughness feature values of the current sample blocks, and the feature values will be written into current RMS. Press key to calculate the arithmetic average value of the current RMS and the previous feature values, and the average value will be written into the average RMS. The total number of the effective measurement amount adds for 1. Press key to store the average RMS value in the table, the measurement of the feature values of the current sample block has completed. The transducer should move to the next sample block. Press key to transfer the data stored in the table to the host machine via RS232. Press key to delete all the data stored in the table, and the latest stored data will be deleted firstly. 26

15 Press or key to zero the total number of the effective measurement. Total sum of the sample block data: it means the total number of the measurement of the feature value of sample blocks, normally it is as same as the sum of the sample blocks to be measured. Total sum of effective measurement: it indicates the quantity of effective measurement of current sample blocks, that is, the sum of data used to calculate the average value. The system can take 20 feature values to calculate the average value. Press key to return to Model menu. Caution please!! The procedure of model establishment is the key point whether TRL400 can measure accurately, so the operator should be careful to process so as to ensure the data of model establishment come from the effective measurement! How to ensure the effective measurement? The user should pay attention to the following aspects: Because there are the common welding deformation for the sample blocks, when placing the transducer, it should contact with the sample block tightly and there should be no seams. Because the size of the sample block is too small, when measuring, part of the transducer might 27 hang in the air, and there might be some light illuminating into the detector from the hanging part and the accuracy of measurement will be affected. We can place the non-transparent material (such as rubber cushion, etc) with the thickness as same as the sample block under the hanging part. Because the shape of the facula is the rectangular with the length of 3mm and width of 1mm, when measuring the borders of the sample blocks, part of the facula will go out of the sample block, and there will cause the invalid measurement. So the area of valid measurement should be divided from the sample blocks, and such central area should be 3mm far from the upper and low borders Delete in Model menu Press the direction key to make Delete turn red, then press menu, please refer to the figure key to enter the Delete 28

16 Figure Delete the model Press or key to browse the current model parameters in a circular way. Press key to delete the current models, there are three situation of deletion: If the index number of the current model is the largest index number, the model parameters will be deleted directly. If the index number of the current model is smaller than the largest index number, the current parameters will be deleted, and the system will copy the model parameters with the largest 29 index number to the current model. If the index number of the current model is 01 (the default model), it can t be deleted. Press key to return to Model menu Data menu Press the direction key to make Data in the Data menu turn red, then press enter the Data menu, please refer to the figure key to Data Data menu 30

17 The Data menu has the functions of browsing, deleting and delivering the measurement results stored locally. Here the total sum of the stored data is totally the same as that under Measurement menu. Press or key to make the cursor move upwardly or downwardly, when the range of browsing is beyond the four sets of data in the current page, the interface will be renewed automatically. Press key and the stored data will be sent to the host machine via RS232 (the software in the host machine should be launched, and the serial cable should be connect); after delivering, there will be the prompting language at the right upper side. Press key and the storage records indicated by the cursor will be deleted, the last storage record will be filled into the space of this storage record automatically. Press key to return to main menu Status menu Press the direction key to make Status in the Status menu red, then press Status menu, please refer to the figure key to enter the 31 Figure Status menu The Status menu will display some basic information of the instrument. Model: display the number of models stored in this machine and the remaining model space, 64 kinds of models can be stored. Data: display the total number of the measurement results stored in this machine and the remaining storage space, 88 measurement results can be stored. MeansHead: the location of the specular reflection points in the array of photo-sensor inside the transducer. 32

18 Language: The current language used in the interface of the instrument, currently the system only supports Chinese. Version: the current version of the software of the instrument Device: Instrument manufacturers. Press key to return to main menu Time menu Press the direction key to make Time red, then Press to the figure key to enter the Time menu, please refer Figure Time menu 33 Press or key to enter the menu of time altering, and the yellow cursor occurs below the project to be altered; press or key continually and the yellow cursor will be circular among the different projects. Press key to make the time value add 1; press to make the time value minus 1. Press or key to store the altered time value. Press key to return to main menu. Note: The range of year is Instruction to operating tips Operating tips will appear at the right upper corner of the LED screen according to the different 34

19 situations to alarm the operators. : indicates that the reflect light of the measured surfaces is very weak, the roughness of the measured surface is in doubt; the operator should check whether there are dirt or defects on the surfaces. : indicates there are the problems in the installation of the transducer cables, or the laser from the transducer doesn t light in the surface to be measured, so the photo-sensor can t receive the reflected light. The operator should check the transducer installation and the measured surfaces. correct. : indicates that the stored data or the parameters of the stored data are : indicates that the stored data or the parameters of the stored data are incorrect, the operator should store again. If there are tips about errors, the machine should be sent to the factory for repairing. 35 : indicates the data or the feature values of the sample blocks used for sample establishment have been successfully delivered. : indicates the current block has been measured during the block establishment, and the next sample block should be tested. 4 Chapter Four Fitting software -Calibration 4.1 The effects of the fitting software TRL400 is a kind of comparative measurement instrument, it calls for establishing the corresponding verification model for different processing method, that is, the verification curves. For the same processing method, once the verification model has been established, it doesn t need to be verified again. Calibration software is specially developed for TRL 400 instrument, it can receive the feature values uploaded by TRL400 via the serial ports, and fit the verification curve according to these feature value then obtain the verification parameters. It can also download the parameters to TRL 400 via the serial ports, and it also has the functions of data storage, etc. The entire procedure of verification includes: 36

20 1. When the actual roughness value of the standard sample block is unknown, it calibrates the roughness value of the sample block with the indentor-style roughness tester. 2. Use TRL400 to measure the sample blocks; store the measurement results with Setup option under Model menu, then upload the results to the fitting software. 3. Select different fitting methods according to different sample block points. Select the fitting method with the maximum accuracy from them to draw the fitting curve, then store the verification model. 4. Download the values of various parameters (including the verification mode), the measurement units and processing methods to the controllers. Then the controller menu should be under Input sub-menu and Set up sub-menu. Note: Use more verification workpiece surfaces and perform many measurements, such obtained verification model will be more accurate. If the range of the roughness value selected during the verification is wider, the model will be more accurate. What should be paid attention to is that: the indentor measurement usually lacks the repetitiveness. There should be a good method to measure each sample block with indentor 37 for many times; the average value of these values will be input in the fitting software. The results of indentor measurement varied a lot, which is mainly depending on the surface evenness, measurement environment and status of the indentor. 4.2 Instruction to the software Input the original data Calibration software can obtain the fitting data with the methods of document inputting, manual inputting and online uploading. The original data include the verification data and the reference data; the reference data are the roughness values of the sample blocks measured by the indentor method, and the verification data are the roughness feature values of the sample blocks measured by TRL

21 Figure Input original data 39 Figure Input data manually Come from the files: Calibration software can read the data stored in the TXT files, the storage form of data is the float digits of two columns, the verification data and reference data hold for one column each. Online uploading: When the TRL400 operator has measured all the standard sample blocks 40

22 in Model establishment interface, he can press Deliver key or click the Online upload button in the software to upload the verification data online. The software will fit the data in the corresponding locations in the figure automatically. Manual inputting: it includes inputting two kinds of data. When selecting the reference data and verification data, the reference data and the numbering column will turn gray, and the operator should fill the data in the corresponding location and click on the Load button. The software will fill the data in the corresponding location and generate the numbers automatically. Select the reference data and numbers: the reference data and the column of reference data inputting will turn gray; the operator should fill the reference data in the corresponding inputting boxes. The starting number and ending number can be the same or different, and one or more positions should be filled for the reference data. Delete and delete all: select the corresponding number and click on the Delete button to delete all the selected data. Print list: it can print the verification data and reference data Fitting curve 41 Figure Fitting curve 42

23 Before fitting, the user should select the corresponding processing methods and materials, as well as the units. TRL400 verification model is normally divided in three areas according to the different roughness value; for the smooth surface (the roughness is under 0.05um), it is normally the index correlation, then is the area of linear correlation (the roughness is 0.05um um), the last is also the area of index correlation (the roughness is 0.025um 2.54um). The operator can select the corresponding type of fitting according to this rule and the actual need in the engineering so as to realize the optimum data fitting. The operator can select the suitable break point to fill the number in the break point box; then he can select the proper type of fitting, click on Curve fitting and Display the fitting curves to compete the procedure of curve fitting. Please refer to the figure Click on Save the model parameters and save them in the local hard disk as txt files. Click on Download the model parameters, if TRL400 is currently under the Input menu and Setup sub-menu, the current model parameters (such as A1 and B1) will be downloaded to the instrument. Now we will briefly introduce the function of the button Sort and average. In order to make the user select the break points correctly, the data in the original data list is sorted according 43 to the order of from smaller to larger. But the inputting of the original data might not meeting this requirement, so one functions of this button is to realize the data sorting; besides, during the actual measurement, the user should use the method of measuring for main times and obtaining the average value, that is, many different verification data should be obtained for the same reference data, after inputting these data in the list, press this button and obtain the average value of the verification data. Then the user can select the break point correctly according to the data in the list Uploading the measurement data Figure Uploading the measurement data The measurement data can be uploaded to the PC for storage. When TRL 400 is under the Data menu, click on Download Model Parameters, the measurement data can be uploaded to 44

24 the PC, and they will be displayed in the table of the total measurement data. Click on Save and save them in the hard disk as savedata.txt. Click on the Exit button to close Calibration software. 5 Chapter Five Maintenance and Repairing 5.1 Environmental requirements and battery maintenance The collision, heavy dust, moisture, heavy magnetic field and greasy dirt should be strictly avoided. It is strictly prohibited to wipe the housing with dissolving materials. Instruction: 1. The input voltage of the power adapter is 220V AC, and the output voltage is 9V AC. The maximum charging current is about 1700mA and the longest charging time is about 6h. 2. lithium ion battery is used, so when the symbol of under-voltage occurs, please charge in time, otherwise the battery might be damaged. 3. If the instrument hasn t been used for a long time, please charge the instrument once a month, otherwise the instrument might not been normally used because of over-discharging. 4. If the normal charging can t be performed because of the over-discharging of the battery (the battery has no voltage and the charging LED doesn t light up), the user can take off the power 45 adapter for two minutes and charge again. Repeating this operation for many times, and the battery can recover to normal status. 5. This instrument can work while being charged. 5.2 Handling the failures If there are messy codes, halted system and other phenomenon for the instrument, power off for one minute and re-power on the instrument, generally and the failures will be eliminated. If the following abnormal situation still occur after the instrument is launched again: The battery has been fully charged, or the adaptor can work normally, but the instrument can not be launched or shut down. The instrument can t measure. The transducer can t work normally, or there are no laser emitted. The keys don t work. Storage error is displayed when storing. The measurement values vary frequently. The user shouldn t disassemble the tester and repair by himself. After he had filled in the warranty card properly, he should deliver the instrument to the maintenance department of 46

25 our company and we will execute the maintenance regulations. 5.3 Safety instructions The design of this instrument meets the relative safety standards. When using, it should meet the regulated external environmental conditions, and the operators should have the corresponding technical background so as to ensure the safe operation. Before the instrument is put into use, please read the following safety instructions carefully: Note: 1. This instrument is used to measure the surface roughness and it can t be used in any other ways. 2. This instrument can only be used in the laboratories or under the industrial environment. The system power This instrument can be powered by the external power adaptors or the lithium ion batteries inside. In order to prevent fire, explosion and other accidents during the charging and using, please operate the charging according to our operation steps. If the battery is aging, please contact with us. 47 The system software Any software may have errors, but we strive for reducing the possibility of such errors in minimum level. The software of this instrument has been tested in an all-around and strict way. Accidental failures If the following abnormal conditions occur, there have been the failures for the instrument. Please power off the instrument and deliver the instrument to the designated repair place for repairing. The instrument has been obviously mechanically damaged (such as the serious extrusion or collision during the transportation. The keyboard or screen of the instrument displays abnormally. The instrument has been stored in the environment of high temperature, high moisture and serious corrosion for long time. 6 Appendix 6.1 The list of non-warranty parts Housing (including the upper cover, lower cover, LED window, keyboard cap, alternative manhead, nameplate, etc); 48

26 Power adaptor; Leather sheath; Note: 1. There are highly precise components inside the transducer of TRL400, please do not try to disassemble the host machine and transducer, so as to prevent the dropping and other artificial accidents. 2. The damage caused by the proper using or other artificial reason is excluded in the range of warranty. 6.2 The principles and steps of the transducer installation and alignment If the user wants to obtain the accurate and highly repetitive measurement data, he should keep the 49 alignment and cleaning measured surface. We can use the gasoline or alcohol to clean the surface, but as for the alignment, it should be described in various conditions. The visible laser (wave length = 650 nm) illuminate the surface to be measured with the certain angles, the distribution of the surface reflecting and scattering will be detected by the detecting array composed of 35 tightly connecting detecting units. The user can utilize the relative distribution of the reflected or deflected light to calculate the roughness of the lit surface, and use the software to scan the detecting array so as to find the mirror reflecting light and the position and determine the distance between the measurement transducer and the surface. The following image is the block diagram of the transducer system. 50

27 Annex Figure 1 The diagram of the transducer system The incident angle of the laser in the transducer is very large, which can make the instrument measure the same surface features as the method of indentor, but at the same time, it is very sensitive to the inaccuracy at the perpendicular direction. 51 The mirror-reflected light must fall in any of the former 11 detecting units out of 35 detecting units, and the latter 24 detecting units are used to calculate the surface roughness values. If the distance between the transducer and the surface is too near, the mirror-reflected light will fall in the 12th unit or the unit with larger number. Because there are only 35 units, and 12+24=36, there have no sufficient detecting units of scattered light to calculate the roughness value. If such distance is too large, the mirror-reflected light might fall outside of the detector and it can t be detected and cause the invalid measurement. In order to ensure the normal working of the transducer and simplify the measurement, there will be a chassis for TRL 400, which has been installed at the bottom of the transducer. This chassis is used for the alignment in the perpendicular direction during the measuring of the surface roughness of plain boards. It should ensure the mirror-reflected light fall in the middle part of the former 11 detecting units. If the user must get rid of the chassis during the measurement for other reasons, he should make the distance between the transducer and the measured surface even, and keep the thickness of one chassis (about 0.1 inch). For the measurement of the roughness of curved surface, the standard chassis can t meet the requirements of measurement. We should re-design the clamps. The general designing principles for the clamps are also perpendicular alignment and interval warranty, so as to ensure 52

28 the mirror-reflected light fall in the middle part of the former 11 detecting units. For example, when measuring the cylinder working pieces, the clamps can have the triangular slots in the sections. The angle of the slot is depending on the distance between the detector and the working pieces. By such way the perpendicular alignment and interval can be warranted. The hidden surfaces (such as blind hole or O-shape slot) can t be measured, for the hidden bottom can t be illuminated. And their wall usually hides the incident and the reflect light. The following image indicates the measurement of the hidden surface. 53 Annex figure 2 The hidden surface If the self-designed clamps can t meet the requirements of measurement, please contact with the TRL 400 manufacturers, and the manufacturers will provide the corresponding service according to the situations. 54