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Labsphere DRA-CA-3300 Скачать руководство пользователя страница 46

AQ-00275-000, Rev. 3

45

as in a mirror.

total transmittance:

 the ratio of the flux transmitted at all forward angles to the incident flux.

transmittance:

 the ratio of transmitted flux to incident flux, under specified geometric and spec-

tral conditions.

transmittance factor:

 the ratio of the flux transmitted by a specimen and evaluated by a receiver 

to the flux passing through the same optical system and evaluated by the receiver when the speci-
men is removed from the system.

Discussion-

In some cases, this quantity is practically identical to the transmittance, but it may dif-

fer considerably. It exceeds unity if the system is such that the specimen causes more light to reach 
the receiver than would in its absence.

Содержание DRA-CA-3300

Страница 1: ...Measurements 17 0 Diffuse Reflectance Factor Measurements 18 Large Sample Reflectance Measurements 18 Transmittance Measurement Procedure 19 Theory of Operation 21 Double Beam Spectroscopy 21 Reflecta...

Страница 2: ...es the means of measuring opaque turbid and reflecting substances using the same basic procedures used in traditional measurements Your DRA CA 3300 is an integrating sphere accessory that replaces the...

Страница 3: ...absorbance measurements as before The DRA CA 3300 reflectance accessory is designed for use with the CARY 100 300 UV VIS Spectrophotometers The sphere accessory is an optical bench composed of double...

Страница 4: ...Components DRA CA 3300 Accessory with instruction manual Tool Kit Three USRS 99 020 Uncalibrated Spectralon Reflectance Standards Center mount Port Plug Reflectance Port Light trap fits in sample hold...

Страница 5: ...tance Standard Variable Angle Center mount Sample Holders VASH Clip used for analyzing thin films Variable Angle Center mount Sample Holders Jaw used for analyzing opaque rigid solids Fixed Angle Cent...

Страница 6: ...er accessories from the instrument sample compartment 2 Slide the instrument sample compartment cover back Remove the compartment front panel Note the position of the detector DB connector inside the...

Страница 7: ...trument Otherwise install the accessory with the cable unconnected 8 Position the accessory over the alignment pin in the back until the head of the assem bly fits tightly against the front panel of t...

Страница 8: ...ports 15 Store the optics chamber cover handle and front panel to the spectrophotometer sam ple compartment in a safe place 16 Upon first time installation check the optical alignment of the accessory...

Страница 9: ...e inch square of translucent paper that clearly displays the outline of the sample or reference beam when illuminated When performing this procedure the accessory control cable should be disconnected...

Страница 10: ...need a one inch square of translucent paper that clearly displays the outline of the sample or reference beam when illuminated When performing this pro cedure the accessory control cable should be di...

Страница 11: ...overfill the port b For transmittance measurements turn the adjustment screws of mirror M3 until the beam is centered on the transmittance sample port In this configuration the sample beam will overfi...

Страница 12: ...ion manual contains the procedures for a series of diagnostic scans on your accessory These scans were performed on your accessory with our instrument before we shipped the DRA CA 3300 to you You shou...

Страница 13: ...drive Note Be sure to remove the plate from the beam path when the scan is complete Light Trap Zeroline After completing an Uncorrected Baseline scan as described above perform a light trap zeroline a...

Страница 14: ...as listed on the Labsphere diagnostic scan reports in the quality assurance documentation 2 Change the instrument configuration to Single Front beam mode from the Setup Dia log Box 3 Place a Spectral...

Страница 15: ...pplications Integrating Sphere The integrating sphere assembly shown in Figure 6 is 150 mm in diameter and constructed of Spectralon Spectralon is the same material used on the standards supplied with...

Страница 16: ...om well of the sample compartment When the cable is plugged in correctly the instrument will recognize the presence of the DRA CA 3300 accessory during initialization Optical Chamber The optical chamb...

Страница 17: ...e the reflecting surface lies flat against the wedge and completely fills the port surface area In some instances you may need to load a light trap at the reference or sample reflectance port A light...

Страница 18: ...ion provides an unfocused spot size of approximately 20 mm wide x 25 mm high Place the mirror in the center mount position if an intermediate beam size is desired The 8 reflectance measurement capabil...

Страница 19: ...1 Replace the 8 sample wedge with the 0 wedge at the sample reflectance port 2 Load the calibrated SRS 99 020 diffuse standard into the sample port and the uncali brated standard at the reference por...

Страница 20: ...x 9 5 mm high If a large transmittance spot size is desired such as for the measurement of fabrics or other homogeneous samples place mirror M3 in the reflectance R position This mirror configuration...

Страница 21: ...nown as the regular transmittance factor For this particular accessory how ever the regular transmittance factor of a scattering sample closely approximates the total trans mittance of the sample Diff...

Страница 22: ...io recording spectrophotometer the measurement of reflectance factor and transmittance involves the performance of a Baseline Correction based upon values recorded in an Uncorrected Baseline Baseline...

Страница 23: ...e or eliminate the effect of such factors on transmittance and reflectance factor measurements In transmittance measurement the transmittance Ts of a non scattering sample placed in the path of the sa...

Страница 24: ...on described in this manual The foregoing account involves two simplifying assumptions that bear further discussion First the efficiency of the integrating sphere represented by s and r is not necessa...

Страница 25: ...be measured rela tive to a standard with similar geometrical scattering properties If calibrated standards that meet this criterion are not available as is often the case another approach must be take...

Страница 26: ...he value M given in Equation 7 and its relation to the actual specular component of hemispherical reflectance S is described in Equation 12 On this analysis the best estimate for the 8 hemispherical r...

Страница 27: ...e scan and record the measurement data The light trap reflectance is 0 3 Compute the corrected reflectance factor for the sample s as follows where r is the reflectance value of the reference standard...

Страница 28: ...surface of your sample should coincide with the inside surface of the sphere wall Most sample surfaces however are not spherical in design so that some small portion of diffuse reflection may be direc...

Страница 29: ...cations A variable angle center mount sample holder enables the sample reflectance and absorbance to be studied at various beam incidence angles The typical variable angle center mount sample holder u...

Страница 30: ...ntegrating sphere and may interfere with the radiance uniformity at the wall surface Edwards Style Center Mount The Edwards attachment can be used to measure the variable angle reflectance of diffuse...

Страница 31: ...iffuse samples can be measured using this sample holder in an absolute fashion Specular reflectance samples may be measured with the Edwards attachment if it is used in a relative mode and the sample...

Страница 32: ...mples at sphere center An illustration of a jaw style sample holder is shown in Figure 13 The jaws easily will accommodate sample sizes up to 1 5 in length and width This is the size of a Labsphere SR...

Страница 33: ...the transfer optics in the accessory 1 Load the sample into the sample holder making sure it is properly centered and secured to the holding device 2 Load the sample holder into the center mount port...

Страница 34: ...suring turbid samples such as sea water proteins and other biological solutions Measurements performed with this device are in the diffuse specular excluded geometry Since the CMSH 3300 CUV is fixed a...

Страница 35: ...transfer optics using the procedure under Aligning the Accessory Optics this time shifting mirror M3 to the C position When aligning M3 look into the sphere using the translucent paper and ensure that...

Страница 36: ...oles Take care when inserting or removing the center mount from the integrating sphere to avoid damaging the interior of the sphere 5 Set your instrument parameters 6 Perform an instrument baseline co...

Страница 37: ...ally to achieve the desired sample den sity 4 When the powder cell holder is filled to the required density or when the sample reaches the top of the cell cavity carefully slide the quartz window back...

Страница 38: ...e relative reflectance value changes with changes in the sample packing density If you wish to compare subsequent sample measurements then take care to ensure that sample presentation to the beam and...

Страница 39: ...cuvette filled with your solvent 3 Set your instrument parameters Set the Y Mode on the Setup Dialog Box of your WinUV software to absorbance or T 4 Perform an instrument baseline correction 5 Replac...

Страница 40: ...r handled with bare fingers However the mirrors do have a protective magnesium fluoride overcoat to allow cleaning if necessary The fol lowing procedure is recommended 1 Remove the mirror fixture 2 Sp...

Страница 41: ...lems that develop when using an accessory can be traced back to the instrument itself check that your instrument light source is operating satisfacto rily Check that the accessory cord is securely att...

Страница 42: ...the lifetime of the PMT by keeping the center mount port on top of the integrating sphere plugged and the accessory lid closed when not in use Except for optics alignment never run a scan or operate t...

Страница 43: ...Reflectance Port 1 dia Transmittance Port 25 mm Measurement Capability Reflectance Total 8 Diffuse 0 Transmittance Total PMT Detector Hamamatsu R928 Spectral Range 185 900 nm Peak Wavelength 400 nm G...

Страница 44: ...actors Wavelength Spectralon 8 Hemispherical Reflectance 250 973 300 984 400 991 500 991 600 992 700 992 800 991 900 991 1000 993 1100 993 1200 992 1300 993 1400 991 1500 992 1600 992 1700 988 1800 98...

Страница 45: ...n from a surface varies as the cosine of the angle between the normal to the surface and the direction of the direc tion of the emitted flux also called Lambert s cosine law mixed reflection partly sp...

Страница 46: ...ance factor the ratio of the flux transmitted by a specimen and evaluated by a receiver to the flux passing through the same optical system and evaluated by the receiver when the speci men is removed...

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