What is the angle of optical axis at the exit pupil of lightcommander?

Shalin,

Hello, and welcome to the DLP forum.

In the Light Commander Kit, the center of the  DMD is dropped 5.4 mm below the optical axis of the lens. The entire DMD is still well within the 43 mm "illumination circle" of a full-frame 35mm camera lens, such as the Nikon 50 mm lens supplied with the LightCommander. The reason for the drop below the optical axis is to cause the image of the DMD to project above the horizontal plane - which is helpful when the LC is sitting on a table.

Here is a drawing of this offset, looking directly into the Light Commander at the lens mounting flange:

The outer circle is the imaging circle of a FX lens. The dotted circle is the imaging circle of a DX lens. The blue rectangle is the mirror array of the DMD.

I do not have a schematic of the optical path.

Best regards,

Pascal

Shalin,

Hello, and welcome to the DLP forum.

In the Light Commander Kit, the center of the  DMD is dropped 5.4 mm below the optical axis of the lens. The entire DMD is still well within the 43 mm "illumination circle" of a full-frame 35mm camera lens, such as the Nikon 50 mm lens supplied with the LightCommander. The reason for the drop below the optical axis is to cause the image of the DMD to project above the horizontal plane - which is helpful when the LC is sitting on a table.

Here is a drawing of this offset, looking directly into the Light Commander at the lens mounting flange:

The outer circle is the imaging circle of a FX lens. The dotted circle is the imaging circle of a DX lens. The blue rectangle is the mirror array of the DMD.

I do not have a schematic of the optical path.

Best regards,

Pascal

Hello Pascal,

Thanks very much for the information. It is helpful to know that DMD is offset from the center of the optical axis.

But the original question I had is not resolved. I try to rephrase the question below.

I will use the lightcommander in a microscopy application without the kit lens with optics module, controller board, and power supply mounted on a bench. In need to know the direction in which the light-ray will propagate from the ON mirror of the DMD. When I look down the DMD in light-commander's optics module from front, will the light-ray bouncing off the ON mirror come out exactly perpendicular to the rectangle you have drawn? Since the DMD mirrors are hinged on the diagonal and flip by +-12 degrees, they will deflect light in both horizontal and vertical direction. I am wondering if the light-path is engineered so that the light-rays exiting from the DMD are exactly perpendicular to the DMD.

Best

Shalin

Shalin,

No, the light rays reflecting from the DMD from the Light Commander illumination system are not exactly perpendicular to the DMD, or all the same. That would require a telecentric illumination system, which the Light Commander does not have. The LC illuminator is not telecentric, but it is designed for good projection performance. It is probably not optimal for the microscopy application which you are considering.

The Light Commander consists of modular components which can be modified or replaced by the customer. It would probably be possible to design a telecentric illuminator. It is possible to remove the control board and DMD board from the LC case and mount them on an optical bench (with suitable clamps and hardware). This would allow you to experiment with telecentric illumition, and also to center the DMD in the optical path, rather than having the offset which is used in the LC as delivered.

I hope these suggestions help.

Best regards,

Pascal