PI035
IR Linear Polarizing Filter

A general discussion about polarizers, how they work and their applications can be found in the "POLARIZING FILTERS" section of this web site (article to come). Although they will certainly transmit infrared light without any problem, visible polarizers do not work in the near infrared. MidOpt near-infrared polarizers are for use in the 850-2000nm range. The extinction ratio over this range is 1,000:1 to 10,000:1; polarizing efficiency is 99.9 to 99.99%.

Single substrate lnfrared linear polarizers are sold in rotating mounts but are also available in "fixed" mounts. Once the filter is screwed into the lens, the upper portion of the mount that contains the linear polarizer can be easily rotated to find the optimum setting.

Because the mount rotates freely, it may be possible to accidentally move the filter and adversely effect the system's performance. For this reason, MidOpt polarizers are supplied with locking thumbscrews to insure that jarring or accidental movement during cleaning does not result in a change in filter position.

The appropriate filter position can be set by first screwing the filter into the mount all the way, and then while observing the image, rotating the filter until the glare disappears or is reduced as much as possible.

MidOpt also offers infrared linear polarizers in Slip Mounts (to fit over the outside diameter of the front of a lens). These mounts are usually employed when the lens does not have a filter thread. In these cases, the mount and filter can be easily positioned on the lens such that rotating mounts are unnecessary.

Download Excel Spreadsheet with data and curve for this filter.

Examples of filter effectiveness.

Standard Threaded Mounts:
We offer standard filter sizes from stock – 22.5mm to 62mm – for same- or next-day shipping. Larger filters – 67mm to 105mm – are made to order and are normally not returnable.

Click here for PDF drawing of standard mounts

Slip Mounts:
If your lens does not have threads for mounting a filter, Slip Mount adapters are available. Slip Mounts can attach a regular filter to a lens or attach a very large filter to accommodate a wide angle lens. Please call to order Slip Mount adapters.

C-Mounts:
3mm thick threaded mount for adding a filter between lens and camera
Click here for PDF drawing of c-mounts

Transmission chart (typical)
Passes visible (340nm+) and IR, or only IR (two types available)
Absorbs UV 200-340nm

1100
1090
1080
1070
1060
1050
1040
1030
1020
1010

1000
990
980
970
960
950
940
930
920
910

900
890
880
870
860
850
840
830
820
810

800
790
780
770
760
750
740
730
720
710

700
690
680
670
660

36.21
36.20
36.22
36.24
36.28
36.27
36.28
36.29
36.32
36.26

36.32
36.33
36.34
36.37
36.45
36.45
36.50
36.49
36.47
36.60

36.65
36.69
36.72
36.77
36.75
36.85
36.88
36.94
36.94
36.92

36.96
37.01
37.10
37.08
37.00
36.30
35.82
34.42
30.38
24.28

12.91
6.05
0.27
0.01
0.00

650
640
630
620
610
600
590
580
570
560

550
540
530
520
510
500
490
480
470
460

450
440
430
420
410
400
390
380
370
360

350
340
330
320
310
300
290
280
270
260

250
240
230
220
210

0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00

0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00

0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00

0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00

0.00
0.00
0.00
0.00
0.00