滤光片
光学滤光片广泛应用于衰减特定波长的光线，从而生成探测器所需的总体响应。
干涉滤光片利用波之间的谐波干涉效应，创造出极为狭窄的通带。其设计原理在于，薄金属膜通过电介质间隔层被精确地分隔开，间隔为所需波长的一半。这种滤光片能够实现的带宽小于10nm。
吸收滤光片则通常由玻璃材料制成，这些玻璃中掺杂了一定浓度的染料，这些染料能够吸收特定颜色的光线。由于光谱透射率与滤波器的厚度之间呈对数关系，因此，通过增加滤光片的厚度，可以有效地减小其通带宽度。
布格定律（Bouguer's law）深入阐述了滤光片厚度对其透射率的影响。对于由相同材料制成的两个滤滤光片，其内部透射率τ与厚度d之间满足关系式：log10(τ1) / d1 = log10(τ2) / d2。需要注意的是，由于反射损失的存在，滤光片的内部透射率总是大于其外部透射率。
菲涅耳反射定律（Fresnel's law of reflection）则揭示了光线在介质界面上的反射规律。对于正入射光线，反射光的比例r可以通过公式r = (n-1)² / (n+1)²来计算，其中n为两种介质的折射率之比。以空气和玻璃为例，当n=1.5时，每个表面的反射光比例约为4%。因此，两个由空气隔开的滤光片相比由光学胶（甚至水）连接的滤光片，其透射率会降低约8%。
为了匹配特定的功能需求，如国际照明委员会（CIE）定义的光视效率函数（该函数描述了人眼对颜色的敏感度），我们可以将多个彩色滤光片进行叠加使用。组合后的光谱响应是各滤光片透射率与探测器光谱响应度的乘积。由于光谱透射率与滤波器厚度之间的对数关系，我们可以通过增加滤光片厚度来进一步减小其通带宽度。
ILT的光学滤光片是我们仪表在各种应用场景中的核心组件。这些滤光片被安装在经过黑色阳极化处理的、带有1 1/4-24螺纹的环中，可以方便地在SED、SEL和SHD探测器上进行互换。此外，我们还提供未安装的滤光片和空滤光片环供客户选择。
为了满足特定应用的需求，ILT还能够创建加权测量功能。例如，在新的紫外线致黑斑效应危害标准中，关键波长下的紫外线暴露对生物体的影响远大于附近波长的暴露。为了准确测量这种影响，ILT使用薄膜技术或复合吸收层叠技术对每个波长的灵敏度进行加权处理。如果您需要技术帮助或了解更多关于适用于您应用的滤光片或滤光片组合的信息，请点击下面的“联系我们”按钮并填写表格与我们联系。
您可以通过点击下面的“联系我们”按钮并填写表格来咨询更多信息。
| Part Number, Description | Specifications |
|---|---|
| A, Photoresist Filter | Tailored filter designed to provide 'A' response (320-475 nm) with silicon sensors. |
| ACT5, Actinic/Germicidal Filter | Multipurpose filter produces expanded actinic response or effective germicidal/bactericidal response when used with SED(SEL)240 Detector as well as UV Actinic Hazard response curve per ACGIH. |
| T2ACT5, Actinic Germicidal Filter / Diffuser | ACT5 combined with T2X Diffuser. Provides extra sensitivity with good spatial response required for use with ILT1400 for optical hazard measurements. |
| B, Photoresist Filter | Filter designed to provide 'B' response (326-401 nm) with silicon detectors. |
| BAS, Bilirubin Action Spectrum | Blue light filter designed to modify the spectral sensitivity of silicon sensors to match the Bilirubin Action Spectrum curve |
| FUVC Far UV Filter | Interference filters with center wavelength at 230 nm nanometers. Used to block longer wavelengths for testing excimer 222 nm lamps. |
| F, Flat Response Filter | Filter to be combined with silicon detectors to produce a flat spectral response. |
| HMR-1, Hot Mirror | IR rejecting hot mirror. Combined with F filter for flat VIS response. |
| NS185, Narrow Band Filter, UV | Interference filter with center wavelength 185 nm. |
| NSXXX, UV Narrow Band filters, Ultraviolet | Interference filter with center wavelength at XXX nanometers, FWHM 10 nm. Standard filters available are NS254, NS280, NS313, NS335, NS350, NS365. |
| NSXXX, Visible Narrow Band Filter, Visible | Interference filters with center wavelength at XXX nanometers, FWHM 10 nm. Standard filters available are NS400, NS405, NS436, NS500, NS546, NS600, NS633 and NS700. |
| NSXXX, custom | Interference filter with center wavelength at XXX nanometers, for ranges not noted above. CUSTOM NSUV, NSVIS and NSIR, with many FWHM and CW ranges available, contact technical support for assistance. |
| NDFSS102, Neutral Density Filter Set | UV-IR: filters mounted to fit SED(SEL)(SHD)(SL) detectors. QNDS1, QNDS2 and QNDS3 included. |
| PAR-1, Photosynthetically Active Radiation | Tailored filter to be combined with silicon detectors. Combined quantum response is spectrally flat in the visible range. |
| QNDS1, Neutral Density Filter | Quartz filters with 10 times attenuation. |
| QNDS2, Neutral Density Filter | Quartz filters with 100 times attenuation. |
| QNDS3, Neutral Density Filter | Quartz filters with 1000 times attenuation. |
| SCSXXX, Sharp Cut Filters | Glass filters with a wavelength of XXX at 60% transmission. They pass wavelengths above XXX and absorb wavelengths below XXX. Standard filters available are SCS280, SCS365 (LIMITED AVAILABILITY), SCS395, SCS440, SCS465, SCS490, SCS520, SCS530, SCS545, SCS590, SCS605, SCS622, SCS650, SCS695, SCS740, SCS780, SCS810, SCS830. |
| BLUE, Blue Color and Hazard Filter | Filter mounted for use with silicon detectors. |
| TFRD, Far Red Color Filter | Filter mounted for use with silicon detectors. |
| TRED, Red Color Filter | Filter mounted for use with silicon detectors. |
| TLS312, Narrowband UVB Phototherapy Filter | Narrow band filter for use with GaAsP detector, for TL-01 lamp measurement. |
| UVA, Phototherapy Filter | Filter, when combined with silicon detector, produces UVA response from 315 to 390 nm (10%). |
| UVB-1, Phototherapy Filter | Filter, when combined with solar blind vacuum photodiode, produces response from 265 to 332 nm. |
| UVB-2 | Includes both a short pass and long pass filters to block UVC and UVA. Passes light from 280-310 nm. |
| UVF | Flattens response of the 005 series UV-Visible GaAsP Detector over a range of ~350-405 nm (full range 275-450 nm) |
| WBSXXX, Wide Band Filters, UV-IR | Mounted glass filters with center wavelength at XXX nanometers. (note, many WBS filters cannot be used with silicon sensors due to secondary response in the IR, so they are typically sold with the SED(SEL)005. Standard filters available are WBS320, WBS350, WBS375, WBS400, WBS405, WBS440, WBS460, WBS465, WBS480, WBS520. |
| Y4 Photopic Correction Filter | Proprietary blend of filter glasses combined to modify the spectral sensitivity range of ILT's silicon sensors to create and excellent match to the CIE photopic curve (with F' of 1.56). Works with ILT's SED033 and SED100 sensors to provide accurate lux, lumen, and cd/m2 readings when combined with optics and calibrations. |
| ZCIE, Scotopic Filter | Filter used with silicon detectors to produce a match to the CIE Scotopic Response. |
| ZPM, Scotopic Filter | Scotopic correction filter corrects photomultiplier SPM068-1 to CIE eye response to allow low light level cd/m2, lux and lumens measurements. |
