In the last 10-15 years, there has been a shift in the design of microscope systems. Many new and complex microscopy applications require additional components such as filters, dichroic mirrors, and similar elements. We refer our readers to this previous blog about scanning and fluorescent microscope design

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Infinityoptical system

Figure 2. In an infinity corrected system, the objective lens creates a series of collimated rays and the tube lens creates the intermediate image. Figure from Edmund Optics.

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The main consequence of this small change is that we don’t have a set distance between the objective lens and the tube lens (although it is usually set somewhere between 160mm to 200mm) and it is possible to add optical elements in between without affecting the quality of the image. Figure 2 shows an infinity corrected system

Objective lens

The objective lens will create a real image somewhere in the tube. This image is usually referred to as an intermediate image. The eyepiece is then placed such that it will create a virtual image out of the intermediate image. This allows the user to relax their eye and focus away from their near focal distance reducing strain on their eyes. Figure 1 shows a simplified version of an finite microscope optical layout.

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One limitation of finite microscope is that the tube length distance is fixed (usually at 160 mm) and if we add any elements in the tube, this distance will be affected and we will need to redesign our eyepieces and objective lenses. This can increase cost and may introduce unwanted aberrations.

TIRlens

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With over 20 years of experience and 800+ unique optical systems designed, Optics for Hire specializes in advanced optical engineering. If it uses light, we've worked on it.

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With over 15 years of experience and 500+ unique optical systems designed, Optics for Hire specializes in advanced optical engineering. If it uses light, we've worked on it.

Tubelens

Traditional microscope systems consist of two main optical elements: a microscope objective and an eyepiece. The microscope objective is placed close to the sample that we want analyzed. The distance between the objective lens and sample is called the working distance and depends on the magnification of the objective lens.

One solution is the introduction of infinity corrected lenses. In this microscope’s optical design, the objective creates the image at infinity and a new optical element called the tube lens creates the intermediate image that is picked up by the eyepiece.

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