**4. Conclusions**

We developed a TEM equipped with a NEA-InGaN photocathode electron gun with an accelerating voltage of 50 kV and evaluated its performance by imaging with a pulsed electron beam. The cathode has a long lifetime and can be imaged even after about 2 years of NEA surface treatment. Under the conditions, a bright-field image can provide an S/N ratio of 1 or more with an exposure time of 800 ms. By increasing the emittance further, the temporal and spatial resolutions can be improved.

**Author Contributions:** Conceptualization, T.N.; Data curation, S.I. and S.H.; Investigation, Y.H.; Writing—original draft, H.Y.; Writing—review & editing, H.A. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by MEXT/JSPS KAKENHI, Grant Number JP19H00666, and by the joint research of "Research on observations by semiconductor photocathode electron beams".

**Conflicts of Interest:** The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
