標準紅外長通濾波器，應用于順序分類的長波通濾光片
LWP的英文全稱Long Wave Pass，意為長波通或高波通。美國Andover公司推出的紅外長通濾光片，又被稱為長波通濾波片或紅外高波通濾波器。長波通濾光片在特定波長下提供銳截止。Andover長通濾波片通常用于順序分類，它們隔離了廣泛的光譜區域，同時提供所需波段的高透射率，以及深入抑制不需要的波段。Andover長波通濾光片由光學質量的紅外透射基板上的堅硬耐用的表面電介質鍍膜構成，這些長波通濾波片能承受與任何高質量光學部件相關的正常清潔和處理。
高波通濾光片提供三種標準尺寸的濾波片：12.5mm、25mm和50mm直徑，具有統一的中心厚度1mm，此外Andover也提供定制尺寸和形狀，以及定制的光學特性。中紅外高波通濾波片的工作溫度涵蓋-62°C至+71°C，因此具有廣泛的應用。硅或鍺是紅外長波通濾光片的主要基底材料，其平行度小于10弧分，平均反射率小于0.1%，平均透過率>85% （from 1.05 x cut-on to 2.0 x cut-on）。中紅外長通濾波片的平面度小于5 waves （at cut-on W/L），斜率小于7% (12% for 1.05µm filter)。
Andover中紅外高波通濾光片的標準品：
| 型號 | 5%波長(nm) | 類型 | 尺寸(mm) | 厚度(mm) | Scratch-Dig | 通光孔徑 | 平面度 |
| 1.05ILP-12.5 | 1050.0±40 | LWP | 12.5+0/-0.2 | 1.0±0.2 | 80/50 | 11.0mm-min | 5 or better at of Interest |
| 1.05ILP-25 | 1050.0±40 | LWP | 25.0 +0/-0.2 | 1.0±0.2 | 80/50 | 22.0mm-min | 5 or better at of Interest |
| 1.05ILP-50 | 1050.0±40 | LWP | 50.0 +0/-0.2 | 1.0±0.2 | 80/50 | 45mm-min | 5 or better at of Interest |
| 1.65ILP-12.5 | 1650.0±70 | LWP | 12.5 +0/-0.2 | 1.0±0.2 | 80/50 | 11.0mm-min | 5 or better at of Interest |
| 1.65ILP-25 | 1650.0±70 | LWP | 25.0 +0/-0.2 | 1.0±-0.2 | 80/50 | 22.0mm-min | 5 or better at of Interest |
| 1.65ILP-50 | 1650.0±70 | LWP | 50.0 +0/-0.2 | 1.0±0.2 | 80/50 | 45mm-min | 5 or better at of Interest |
| 2.40ILP-12.5 | 2400.0±90 | LWP | 12.5 +0/-0.2 | 1.0±0.2 | 80/50 | 11.0mm-min | 5 or better at of Interest |
| 2.40ILP-25 | 2400.0±90 | LWP | 25.0 +0/-0.2 | 1.0±0.2 | 80/50 | 22.0mm-min | 5 or better at of Interest |
| 2.40ILP-50 | 2400.0±90 | LWP | 50.0 +0/-0.2 | 1.0±0.2 | 80/50 | 45mm-min | 5 or better at of Interest |
| 3.60ILP-12.5 | 3600.0±140 | LWP | 12.5 +0/-0.2 | 1.0±0.2 | 80/50 | 11.0mm-min | 5 or better at of Interest |
| 3.60ILP-25 | 3600.0±140 | LWP | 25.0 +0/-0.2 | 1.0±0.2 | 80/50 | 22.0mm-min | 5 or better at of Interest |
| 3.60ILP-50 | 3600.0±140 | LWP | 50.0 +0/-0.2 | 1.0±0.2 | 80/50 | 45mm-min | 5 or better at of Interest |
| 4.50ILP-12.5 | 4500.0±180 | LWP | 12.5 +0/-0.2 | 1.0±0.2 | 80/50 | 11.0mm-min | 5 or better at of Interest |
| 4.50ILP-25 | 4500.0±180 | LWP | 25.0 +0/-0.2 | 1.0±0.2 | 80/50 | 22.0mm-min | 5 or better at of Interest |
| 4.50ILP-50 | 4500.0±180 | LWP | 50.0 +0/-0.2 | 1.0±0.2 | 80/50 | 45mm-min | 5 or better at of Interest |
| 6.00ILP-12.5 | 6000.0±240 | LWP | 12.5 +0/-0.2 | 1.0±0.2 | 80/50 | 11.0mm-min | 5 or better at of Interest |
| 6.00ILP-25 | 6000.0±240 | LWP | 25.0 +0/-0.2 | 1.0±0.2 | 80/50 | 22.0mm-min | 5 or better at of Interest |
| 6.00ILP-50 | 6000.0±240 | LWP | 50.0 +0/-0.2 | 1.0±0.2 | 80/50 | 45mm-min | 5 or better at of Interest |
| 7.30ILP-12.5 | 7300.0±290 | LWP | 12.5 +0/-0.2 | 1.0±0.2 | 80/50 | 11.0mm-min | 5 or better at of Interest |
| 7.30ILP-25 | 7300.0±290 | LWP | 25.0 +0/-0.2 | 1.0±0.2 | 80/50 | 22.0mm-min | 5 or better at of Interest |
| 7.30ILP-50 | 7300.0±290 | LWP | 50.0 +0/-0.2 | 1.0±0.2 | 80/50 | 45mm-min | 5 or better at of Interest |
長波通濾波片的主要特點：
- 用于分離寬光譜區域
- 由堅硬、耐用的表面涂層構成
- 有標準和定制波長可供選擇
紅外長通濾光片的主要應用：
- 順序分類
- 傅里葉變換紅外光譜
- 熱成像
